Commission Delegated Regulation (EU) 2015/68 of 15 October 2014 supplementing Regulation (EU) No 167/2013 of the European Parliament and of the Council with regard to vehicle braking requirements for the approval of agricultural and forestry vehicles Text with EEA relevance

• 3.1.5.2.Special requirements in the case of tractors where all axles are permanently rigidly connected (100 % locking rate) by the all-wheel drive or are automatically connected during braking by the all-wheel drive (100 % locking rate)

• 3.1.5.2.1.The mathematical verification pursuant to point 3.1.5.1 is not required.

• 3.1.5.3.Tractors with permanent all-wheel drive other than covered by point 3.1.5.2.

• 3.1.5.3.1.If it is not possible, for vehicles with permanent all-wheel drive or in the condition when the all-wheel drive is connected during braking, to carry out the mathematical verification pursuant to point 3.1.5.1, the manufacturer may instead verify by means of a wheel lock sequence test that, lockup of the front wheels occurs either simultaneously with or before the lockup of the rear wheels.

• 3.1.5.4.However, for tractors which automatically apply the all-wheel drive when the braking is initiated above a vehicle speed of 20 km/h but not automatically connect the all-wheel drive when the service braking system is applied at speeds not exceeding 20 km/h, then it is not required to show compliance with point 3.1.5.1 for the condition when the all-wheel drive is not connected during braking.

• 3.1.5.5.Procedure to verify the requirements set out in point 3.1.5.3

• 3.1.5.5.1.The wheel lock sequence test shall be conducted with the laden and the unladen vehicle on road surfaces having an adhesion level such that wheel locking on the first axle occurs at braking rates between 0,55 and 0,8 from the initial test speed specified in point 3.1.5.5.2.

• 3.1.5.5.2.Test speed:

• 0,9 vmax, but not exceeding 60 km/h.

• 3.1.5.5.3.The pedal force applied may exceed the permissible actuation forces pursuant to point 3.1.1 of Annex II.

• 3.1.5.5.4.Pedal force is applied and increased such that the second wheel on the vehicle shall reach lockup between 0,5 and 1 s after initiating the brake application, until lockup of both wheels on one axle occurs (additional wheels may also lock during the test, e.g. in the case of simultaneous lockup).

• 3.1.5.5.4.1.If it is not possible during the laden test to reach lockup of the second wheel within a period of 1 s, this test may be omitted under the condition that wheel-locking under the conditions as prescribed in point 3.1.5.5.4 can be demonstrated during the unladen test.

• If also in the unladen test it is not possible to reach lockup of the second wheel within a period of 1 s, a third, decisive test shall be carried out on road surfaces with a coefficient of adhesion of not more than 0,3 from a test speed of 0,8 vmax km/h, but not exceeding 60 km/h.

• 3.1.5.5.4.2.For the purpose of the tests according to point 3.1.5.5, a simultaneous lockup of the front and rear wheels refers to the conditions when the time interval between the first occurrence of lockup of the last (second) wheel on the rear axle and the first occurrence of lockup of the last (second) wheel on the front axle does not exceed 0,3 second.

• 3.1.6.Tractors authorized to draw towed vehicles

• 3.1.6.1.The permissible relationship between the braking rate TM/FM and the pressure pm shall lie within the areas shown on diagram 2 for all pressures between 20 and 750 kPa (in the case of compressed air braking system) and 350 and 13 300 kPa (in the case of hydraulic braking system).

3.2.   Tractors with more than two axles

The requirements of point 3.1 shall apply to vehicles with more than two axles. The requirements of point 3.1.2 with respect to wheel lock sequence shall be considered to be met if, in the case of braking rates between 0,15 and 0,30, the adhesion utilised by at least one of the front axles is greater than that utilised by at least one of the rear axles.

4. Requirements for towed vehicles

• 4.1. For drawbar towed vehicles fitted with compressed-air and hydraulic braking systems:

• 4.1.1. For drawbar towed vehicles with two axles the following requirements apply:
• 4.1.1.1. For k values between 0,2 and 0,8: z ≥ 0,1 + 0,85 (k – 0,2) The provisions of point 3.1.1. do not affect the requirements of Annex II relating to the braking performance. However, if, in tests made under the provisions of point 3.1.1, braking performances are obtained which are higher than those prescribed in Annex II, the provisions relating to the adhesion utilisation curves shall be applied within the areas of diagrams 1 of this Annex defined by the straight lines k = 0,8 and z = 0,8.
• 4.1.1.2. For all states of load of the vehicle, the adhesion utilisation curve of the rear axle shall not be situated above that for the front axle for all braking rates between 0,15 and 0,30. This condition is also considered satisfied if, for braking rates between 0,15 and 0,30, the following two conditions are satisfied:
• 4.1.1.2.1. the adhesion utilisation curves for each axle are situated between two lines parallel to the line of ideal adhesion utilisation given by the equations k = z + 0,08 and k = z – 0,08 as shown in diagram 1 and
• 4.1.1.2.2. the adhesion utilisation curve for the rear axle for braking rates z ≥ 0,3 complies with the relation z ≥ 0,3 + 0,74 (k – 0,38).
• 4.1.1.3. For the verification of the requirements of points 4.1.1.1 and 4.1.1.2 the procedure should be as that in the provisions of point 3.1.5.

• 4.1.2. For drawbar towed vehicles with more than two axles the requirements of point 4.1.1 shall apply. The requirements of point 4.1.1 with respect to wheel lock sequence shall be considered to be met if, in the case of braking rates between 0,15 and 0,30, the adhesion utilised by at least one of the front axles is greater than that utilised by at least one of the rear axles.

• 4.1.3. The permissible relationship between the braking rate TR/FR and the pressure pm shall lie within the designated areas in diagram 3 for all pressures between 20 and 750 kPa (pneumatic) and 350 and 13 300 kPa (hydraulic) respectively, in both the laden and unladen states of load.

• 4.2. For rigid drawbar towed vehicles and centre-axle towed vehicles fitted with compressed-air and hydraulic braking systems:

• 4.2.1. The permissible relationship between the braking rate TR/FR and the pressure pm shall lie within two areas derived from diagram 3, by multiplying the vertical scale by 0,95. This requirement shall be met at all pressures between 20 and 750 kPa (pneumatic) and 350 and 13 300 kPa (hydraulic) respectively, in both the laden and unladen states of load.

• 4.3. For drawbar towed vehicles with inertia braking system

• 4.3.1. The requirements according to point 4.1.1 apply also for drawbar towed vehicles with inertia braking system.

• 4.3.2. For drawbar towed vehicles with inertia braking system and with more than two axles the requirements according to point 4.1.2 of this Appendix apply.

• 4.3.3. For the calculation to verify the compliance with the provisions of point 4.1.1.3 the influence of the permissible drawbar force D* (point 10.3.1. of Annex VIII) can be ignored.

5. Requirements to be met in case of failure of the braking distribution system

When the requirements of this Appendix are fulfilled by means of a special device (e.g. controlled mechanically by the suspension of the vehicle), it shall be possible, in the event of the failure of its control, to stop the vehicle under the conditions specified for secondary braking in the case of tractors; tractors authorised to tow a vehicle fitted with compressed-air or hydraulic braking systems, it shall be possible to achieve a pressure at the coupling head of the control line within the range specified in points 3.1.3 and 3.1.4 In the event of failure of the control of the device on towed vehicles, a service braking performance of at least 30 % of that prescribed for the vehicle in question shall be attained.

6. Markings

• 6.1 Vehicles which meet the requirements of this Appendix by means of a device mechanically controlled by the suspension of the vehicle shall be marked in accordance with the requirements laid down in Article 24 of Delegated Regulation (EU) 2015/208 and with the appropriate data to show the useful travel of the device between the positions corresponding to vehicle unladen and laden states, respectively, and any further information to enable the setting of the device to be checked.

• 6.1.1. When a brake load sensing device is controlled via the suspension of the vehicle by any other means, the vehicle shall be marked with information to enable the setting of the device to be checked.

• 6.2. When the requirements of this Appendix are met by means of a device which modulates the air or hydraulic pressure in the brake transmission, the vehicle shall be marked to show the axle loads at the ground, the nominal outlet pressures of the device and an inlet pressure of not less than 80 per cent of the maximum design inlet pressure, as declared by the vehicle manufacturer, for the following states of load:

• 6.2.1. Technically permissible maximum axle load for the axle(s) which control(s) the device;

• 6.2.2. Axle load(s) corresponding to the unladen mass of the vehicle in running order as stated in the test report for the braking requirements approval;

• 6.2.3. The axle load(s) designated by the manufacturer to enable the setting of the device to be checked in service if this is (these are) different from the loads specified in points 6.2.1 to 6.2.2.

• 6.3. The markings referred to in points 6.1 and 6.2 shall be affixed in a visible position in indelible form.  An example of the markings for a mechanically controlled device in a vehicle fitted with compressed-air or hydraulic braking system is provided in accordance with the requirements laid down in Article 5 of Commisison Implementing Regulation (EU) 2015/504 ([^E0002]).

• 6.4. Electronically controlled brake force distribution systems that cannot fulfil the requirements of points 6.1, 6.2 and 6.3 shall have a self-checking procedure of the functions which influence brake force distribution. In addition, when the vehicle is stationary, it shall be possible to carry out the checks laid down in point 1.3.1, by generating the nominal demand pressure associated with the commencement of braking for both the laden and unladen conditions.

7. Vehicle testing

At the time of type-approval, the technical service shall verify conformity with the requirements contained within this Appendix and carry out any further tests considered necessary to this end. The report of any further tests shall be appended to the type-approval report.

Diagram 1

Tractors of category Tb and drawbar towed vehicles of categories R3b, R4b and S2b

(see points 3.1.2.1 and 4.1.1.2)

Image omitted; see official source

Note: The lower limit k = z – 0,08 is not applicable for the adhesion utilisation of the rear axle.

Diagram 2

Permissible relationship between braking rate TM/FM and the coupling head pressure pm for tractors of categories T and C with compressed air or hydraulic braking systems

Image omitted; see official source

Diagram 3

Permissible relationship between braking rate TR/FR and the coupling head pressure pm for towed vehicles of categories S2, R3 and R4 with compressed air or hydraulic braking systems

Image omitted; see official source

ANNEX III

Requirements applying to the measurement of the response time

1. General Requirements

• 1.1. The response time for the service braking systems shall be determined with the vehicle stationary, the pressure being measured at the opening of the least favourably placed brake. For vehicles equipped with load sensing valves, these devices shall be set in the ‘laden’ position.

• 1.2. During the tests, the stroke of the brake cylinders of the individual axles shall be that corresponding to the most closely adjusted brakes.

• 1.3. Response times obtained in conformity with points 2.2, 2.3, 2.4, 2.6, 3.3, 3.4, 3.5, 3.6.5, 4.1, 4.5.1, 4.5.2, 4.5.3, 5.3.6, 6.2, shall be rounded to the nearest tenth of second. If the figure representing the hundredth units is 5 or more, the response time is rounded to the upper tenth.

• 1.4. The diagrams in Appendices 1 and 2 give examples of the correct configuration of the relevant simulators for setting and use.

2. Tractors equipped with compressed-air braking systems

• 2.1. At the beginning of each test, the pressure in the energy storage device shall be equal to the pressure at which the governor restores the feed to the system. In systems not equipped with a governor (e.g., pressure-limited compressors) the pressure in the energy storage device at the beginning of each test shall be 90 % of the pressure specified by the manufacturer and specified in point 1.2.2.1 of Part A of Annex IV, used for the tests prescribed in this annex.

• 2.2. The response times as a function of the actuating time (tf) shall be obtained by a succession of full actuations, beginning with the shortest possible actuating time and increasing to a time of about 0,4 seconds. The measured values shall be plotted on a graph.

• 2.3. The response time to be taken into consideration for the purpose of the test is that corresponding to an actuating time of 0,2 seconds. This response time can be obtained from the graph by interpolation.

• 2.4. For an actuating time of 0,2 seconds, the time elapsing from the initiation of the braking system control device actuation to the moment when the pressure in the brake cylinder reaches 75 % of its asymptotic value shall not exceed 0,6 seconds.

• 2.5. In the case of tractors having a pneumatic control line for towed vehicles, in addition to the requirements of point 1.1, the response time shall be measured at the extremity of a pipe 2,5 m long with an internal diameter of 13 mm which shall be joined to the coupling head of the control line of the service braking system. During this test, a volume of 385 ± 5 cm³ (which is deemed to be equivalent to the volume of a pipe 2,5 m long with an internal diameter of 13 mm and under a pressure of 650 kPa) shall be connected to the coupling head of the supply line. The length and internal diameter of the pipes shall be entered at item 2.4 of the test report.

• 2.6. The time elapsing from the initiation of brake-pedal actuation to the moment when:

• 2.6.1. The pressure measured at the coupling head of the pneumatic control line;

• 2.6.2. The digital demand value in the electric control line measured according to ISO 11992:2003, including ISO 11992-2:2003 and its Amd.1:2007, reaches x per cent of its asymptotic, respectively final, value shall not exceed the times shown in the table below: x [per cent] t [s] 10 75 0,2 0,4

• 2.7. In the case of tractors authorised to tow vehicles of category R3 or R4 fitted with compressed-air braking systems, in addition to the requirements in point 2.6., the prescriptions in point 2.2.1.17.2.1 of Annex I shall be verified by conducting the following test:

• 2.7.1. by measuring the pressure at the extremity of a pipe 2,5 m long with an internal diameter of 13 mm which shall be joined to the coupling head of the supply line;

• 2.7.2. by simulating a failure of the control line at the coupling head;

• 2.7.3. by actuating the service braking control device in 0,2 seconds, as described in point 2.3.

3. Tractors equipped with hydraulic braking systems

• 3.1. The response time tests shall be carried out at an ambient temperature between 15 °C and 30 °C.

• 3.2. At the beginning of each test, the pressure in the energy storage device shall be equal to the pressure at which the governor restores the feed to the system. In systems not equipped with a governor (e.g., pressure-limited hydraulic pumps) the pressure in the energy storage device at the beginning of each test shall be 90 % of the pressure specified by the manufacturer and specified in point 1.2.1.2 of Part C of Annex IV, used for the tests prescribed in this annex.

• 3.3. The response times as a function of the actuating time (tf) shall be obtained by a succession of full actuations, beginning with the shortest possible actuating time and increasing to a time of about 0,4 seconds. The measured values shall be plotted on a graph.

In the case of a service braking system which is activated with no or only a limited assistance of energy a control force shall be applied which ensures at least the prescribed service braking performance.

• 3.4. The response time to be taken into consideration for the purpose of the test is that corresponding to an actuating time of 0,2 seconds. This response time can be obtained from the graph by interpolation.

• 3.5. For an actuating time of 0,2 seconds, the time elapsing from the initiation of the braking system control device actuation to the moment when the pressure in the brake cylinder reaches 75 % of its maximum values hall not exceed 0,6 seconds.

In the case of a full powered service braking system where the brake pressure in the brake actuator reaches a temporary maximum pressure which then falls to the mean stabilised pressure. This mean stabilised pressure should be taken for the calculation of the 75 % value.

• 3.6. Tractors equipped with a hydraulic control line for towed vehicles

• 3.6.1. In addition to the requirements of point 1.1, the response time shall be measured with a towed vehicle simulator (see point 1. of Appendix 2) which shall be joined to the coupling heads of the hydraulic control line and the supplementary line of the tractor.

• 3.6.2. The towed vehicle simulator shall have the following components and characteristics:

3.6.2.1.   Supplementary line towed vehicle simulator

• 3.6.2.1.1. Supplementary line with a female coupling corresponding to ISO 16028:2006 having an orifice with a diameter of 0,6^{+ 0,2} mm in order to limit its flow during the test.

• 3.6.2.1.2. Piston accumulator (or equivalent device) complying with the following characteristics and test conditions:

• 3.6.2.1.2.2. Initial precharge pressure of 1 000 ^{± 100} kPa at a displaced volume of 0 cm³;

• 3.6.2.1.2.3. Maximum pressure of 1 500 kPa at a displaced volume of 500^{± 5} cm³.

• 3.6.2.1.3. The piston accumulator (or equivalent device) is connected with the supplementary line via a connection with an internal diameter of 12,5 mm consisting of a flexible pipe (according to EN853:2007) of 1,0 m length.

• 3.6.2.1.4. A testing port shall be provided as close as possible to the female ISO 16028:2006 coupling.

• 3.6.2.1.5. In order to be able to bleed the simulator before and after the test a bleeding device shall be provided.

3.6.2.2.   Control line towed vehicle simulator

• 3.6.2.2.1. Control line with a female coupling corresponding to ISO 5676:1983

• 3.6.2.2.2. Energy storage device with piston (or equivalent device) complying with the following characteristics and test conditions:

• 3.6.2.2.2.1. Initial precharge pressure of 500^{± 100} kPa at a displaced volume of 0 cm³

• 3.6.2.2.2.2. Intermediate test pressure of 2 200 ^{± 200} kPa at a displaced volume of 100^{± 3} cm³

• 3.6.2.2.2.3. Final pressure of 11 500 ^{± 200} kPa at a displaced volume of 140^{± 5} cm³

• 3.6.2.2.3. The energy storage device with piston (or equivalent device) is connected with the control line via a connection with an internal diameter of 10 mm consisting of a flexible pipe (according to EN853:2007) of 3,0 m and a rigid pipe of 4,5 m length

• 3.6.2.2.4. Testing ports shall be provided as close as possible to the energy storage device with piston (or equivalent device) and to the female ISO 5676:1983 coupling.

• 3.6.2.2.5. In order to be able to bleed air from the connection pipes before the test a bleeding device shall be provided

• 3.6.3. The test shall be performed under the following conditions:

• 3.6.3.1. the connection pipes shall be bleeded from air before the test;

• 3.6.3.2. the engine speed of the tractor shall be at 25 % above idling speed;

• 3.6.3.3. the bleeding device of the supplementary line towed vehicle simulator shall be fully opened.

• 3.6.4. With regard to the measuring of the response time according to points 3.3 and 3.4, the brake control force shall be such to obtain at least a pressure of 11 500 kPa on the coupling head of the control line with the engine running at 25 % above idling speed.

• 3.6.5. For an actuating time of 0,2 seconds, the time elapsing from the initiation of the braking system control device to the moment when the pressure measured at the testing port close to energy storage device with piston (or equivalent device) reaches 75 % of its maximum value according to point 3.5 shall not exceed 0,6 seconds.

However, the maximum value relates here to the pressure measured at the testing port instead of the brake pressure as in the case of point 3.5.

4. Towed vehicles equipped with compressed-air braking systems

• 4.1. The towed vehicle's response times shall be measured without the tractor. To replace the tractor, it is necessary to provide a simulator to which the coupling heads of the supply line, the pneumatic control line and/or the connector of the electric control line are connected.

• 4.2. The pressure in the supply line shall be 650 kPa.

• 4.3. The simulator for pneumatic control lines shall have the following characteristics:

• 4.3.1. It shall have a reservoir with a capacity of 30 litres which shall be charged to a pressure of 650 kPa before each test and which shall not be recharged during each test. At the outlet of the braking control device, the simulator shall incorporate an orifice with a diameter of from 4,0 to 4,3 mm inclusive. The volume of the pipe measured from the orifice up to and including the coupling head shall be 385 ± 5 cm³ (which is deemed to be equivalent to the volume of a pipe 2,5 m long with an internal diameter of 13 mm and under a pressure of 650 kPa). The control line pressures referred to in point 4.3.3 shall be measured immediately downstream of the orifice.

• 4.3.2. The control device shall be so designed that its performance in use is not affected by the tester.

• 4.3.3. The simulator shall be set, e.g. through the choice of orifice in accordance with point 4.3.1 in such a way that, if a reservoir of 385 ± 5 cm³ is joined to it, the time taken for the pressure to increase from 65 to 490 kPa (10 and 75 per cent respectively of the nominal pressure of 650 kPa) shall be 0,2 ± 0,01 seconds. If a reservoir of 1 155 ± 15 cm³ is substituted for the above-mentioned reservoir, the time taken for the pressure to increase from 65 to 490 kPa without further adjustment shall be 0,38 ± 0,02 seconds. Between these two pressure values, the pressure shall increase in an approximately linear way. These reservoirs shall be connected to the coupling head without using flexible pipes and the connection shall have an internal diameter of not less than 10 mm.

• 4.3.4. The diagrams in the Appendix 1 give an example of the correct configuration of the simulator for setting and use.

• 4.4. The simulator for checking the response to signals transmitted via the electric control line shall have the following characteristics:

• 4.4.1. The simulator shall produce a digital demand signal in the electric control line according to ISO 11992-2:2003 and its Amd.1:2007 and shall provide the appropriate information to the towed vehicle via pins 6 and 7 of the ISO 7638:2003 connector. For the purpose of response time measurement, the simulator may at the manufacturer's request transmit to the towed vehicle information that no pneumatic control line is present and that the electric control line demand signal is generated from two independent circuits (see paragraphs 6.4.2.2.24 and 6.4.2.2.25 of ISO 11992-2:2003 and its Amd.1:2007).

• 4.4.2. The braking system control shall be so designed that its performance in use is not affected by the tester.

• 4.4.3. For the purpose of response time measurement the signal produced by the electric simulator shall be equivalent to a linear pneumatic pressure increase from 0,0 to 650 kPa in 0,2 ± 0,01 seconds.

• 4.5. Performance requirements

• 4.5.1. For towed vehicles with a pneumatic control line the time elapsing between the moment when the pressure produced in the control line by the simulator reaches 65 kPa and the moment when the pressure in the brake actuator of the towed vehicle reaches 75 per cent of its asymptotic value shall not exceed 0,4 seconds.

• 4.5.1.1. Towed vehicles equipped with a pneumatic control line and having electric control transmission shall be checked with the electrical power supplied to the towed vehicle via the ISO 7638:2003 connector (5 or 7 pin).

• 4.5.2. For towed vehicles with an electric control line the time elapsing between the moment when the signal produced by the simulator exceeds the equivalent of 65 kPa and the moment when the pressure in the brake actuator of the towed vehicle reaches 75 % of its asymptotic value shall not exceed 0,4 seconds.

• 4.5.3. In the case of towed vehicles equipped with a pneumatic and an electric control line, the response time measurement for each control line shall be determined independently according to the relevant procedure described in points 4.5.1.1 and 4.5.2.

5. Towed vehicles equipped with hydraulic braking systems

• 5.1. The tests shall be carried out at an ambient temperature between 15 °C and 30 °C.

• 5.2. The response times of the towed vehicle shall be measured without a tractor. In order to simulate the tractor, it is necessary to provide a tractor simulator to which the coupling heads of the control line and the supplementary line are connected. If the towed vehicle is equipped with an electrical connector as specified in point 2.1.5.1.3 of Annex I, this connector shall also be connected to the tractor simulator (see point 2. of Appendix 2).

• 5.3. The tractor simulator shall have the following characteristics:

• 5.3.1. The tractor simulator shall be fitted with the types of connections as specified in points 2.1.5.1.1 to 2.1.5.1.3 of Annex I with regard to the tractor.

• 5.3.2. When the tractor simulator is activated (e. g. by an electrical switch):
• 5.3.2.1. a pressure of 11 500 ^{+ 500} kPa shall be generated on the coupling head of the control line,
• 5.3.2.2. a pressure of 1 500 ^{+ 300} kPa shall be present on the coupling head of the supplementary line.

• 5.3.3. When the control line of the towed vehicle is not connected, the tractor simulator shall be capable of generating a pressure of 11 500 kPa at the coupling head of the control line within 0,2 seconds after it was activated (e.g. by an electrical switch).

• 5.3.4. The hydraulic fluid used in the tractor simulator shall have a viscosity of 60^{± 3} mm²/s at a temperature of 40^{± 3} °C (e.g. hydraulic fluid according to SAE 10W30). During the tractor simulator test the temperature of the hydraulic fluid shall not exceed 45 °C.

• 5.3.5. If the towed vehicle is equipped with hydraulic energy storage devices to comply with the requirements for the service braking system, the energy storage devices shall be charged prior to the response time measurements to a pressure as mentioned by the manufacturer in the test report to achieve the minimum prescribed service braking performance.

• 5.3.6. When the tractor simulator is connected to the control line of the towed vehicle simulator (as specified in point 3.6.2) the tractor simulator shall be calibrated in such a way that the time elapsing from the activation of the tractor simulator and the moment when the pressure in the energy storage device with piston (or equivalent device) of the control line of the towed vehicle simulator reaches 11 500 kPa shall be 0,6^{+ 0,1} seconds. To achieve this performance the flow of the tractor simulator shall be adjusted (e.g. by a flow regulator). The connection pipes of the control line of the towed vehicle simulator shall be bleeded from air before this calibration.

• 5.3.7. The control device of the tractor simulator shall be so designed that its performance is not effected by the tester.

• 5.4. Performance requirements

• 5.4.1. When the calibrated tractor simulator (see point 5.3.6) is connected with the towed vehicle, the time elapsing between the moment when the tractor simulator is activated (e.g. by an electrical switch) and the moment when the pressure in the least favourable brake actuator reaches 75 % of its maximum value shall not exceed 0,6 seconds.

In the case of a service braking system, where the brake pressure in the brake actuator reaches a temporary maximum pressure which then falls to the mean stabilised pressure, the mean stabilised pressure should be taken for the calculation of the 75 % value.

6. Tractors equipped with service braking system using spring brakes

• 6.1. The response time measurement has to be carried out with the spring brakes adjusted as closely as possible. The initial pressure in the spring compression chamber, corresponding to this testing requirement, shall be specified by the manufacturer.

• 6.2. The time elapsing from the actuation of the service brake control device (brakes fully released) to the moment when the pressure in the spring compression chamber of the least favourable brake cylinder reaches a pressure corresponding to 75 % of the prescribed braking performance shall not exceed 0,6 seconds.

Appendix 1

Examples of pneumatic simulators

1. Setting the Simulator

Image omitted; see official source

2. Testing the Trailer

Image omitted; see official source

A	=	supply connection with shut-off valve
---	---	---
C1	=	pressure switch in the simulator, set at 65 kPa and at 490 kPa
---	---	---
C2	=	pressure switch to be connected to the brake actuator of the towed vehicle, to operate at 75 per cent of the asymptotic pressure in the brake actuator CF
---	---	---
CF	=	brake cylinder
---	---	---
L	=	line from orifice O up to and including its coupling head TC, having an inner volume of 385 ± 5 cm3 under a pressure of 650 kPa
---	---	---
M	=	pressure gauge
---	---	---
O	=	orifice with a diameter of not less than 4 mm and not more than 4,3 mm
---	---	---
PP	=	pressure test connection
---	---	---
R1	=	30 litre air reservoir with drain valve
---	---	---
R2	=	calibrating reservoir, including its coupling head TC, to be 385 ± 5 cm3
---	---	---
R3	=	calibrating reservoir, including its coupling head TC, to be 1 155 ± 15 cm3
---	---	---
RA	=	shut-off valve
---	---	---
TA	=	coupling head, supply line
---	---	---
V	=	braking system control device
---	---	---
TC	=	coupling head, control line
---	---	---
VRU	=	emergency relay valve

3. Example of a simulator for electric control lines

Image omitted; see official source

ECL	=	Electric Control Line corresponding to ISO 7638:2003
---	---	---
SIMU	=	Simulator of Byte 3,4 of EBS 11 according to ISO 11992:2003 with output signals at start, 65 kPa and 650 kPa
---	---	---
A	=	Supply connection with shut-off valve
---	---	---
C2	=	Pressure switch to be connected to the brake actuator of the towed vehicle, to operate at 75 per cent of the asymptotic pressure in the brake actuator CF
---	---	---
CF	=	Brake cylinder
---	---	---
M	=	Pressure gauge
---	---	---
PP	=	Pressure test connection
---	---	---
TA	=	Coupling head, supply line
---	---	---
VRU	=	Emergency relay valve

Appendix 2

Examples of hydraulic simulators

1. Towed vehicle simulator

1.1.   Supplementary line towed vehicle simulator

Image omitted; see official source

TA	=	coupling head, supplementary line (female coupling ISO 16028:2006)
---	---	---
M	=	pressure test port
---	---	---
PT	=	pressure transducer
---	---	---
P1	=	flexible pipe acc. to EN853:2007 with internal diameter 12,5 mm
---	---	---
A	=	hydraulic accumulator (pre-charge pressure: 1 000 kPa)
---	---	---
B	=	bleeding screw
---	---	---
V	=	bleeding device
---	---	---
O	=	orifice
---	---	---
P2	=	flexible pipe with internal diameter 10 mm
---	---	---
T	=	return to tractor tank

1.2.   Control line towed vehicle simulator

Image omitted; see official source

TA	=	coupling head, control line (female coupling ISO 5676:1983)
---	---	---
M	=	port for pressure gauge or pressure transducer
---	---	---
FP	=	flexible pipe acc. to EN853:2007 with internal diameter 10 mm
---	---	---
RP	=	rigid pipe with internal diameter 10 mm
---	---	---
PT	=	pressure transducer
---	---	---
B	=	bleeding screw
---	---	---
C	=	cylinder/s (*)

Image omitted; see official source

2. Tractor simulator

Image omitted; see official source

F	=	filters
---	---	---
PM	=	pump
---	---	---
PT	=	pressure transducers
---	---	---
CLRV	=	control line relief valve
---	---	---
SLRV	=	supplementary line relief valve
---	---	---
SV	=	3 way solenoid valve
---	---	---
FR	=	flow regulator
---	---	---
MV	=	proportional modulation valve
---	---	---
TA	=	coupling head, supplementary line (male coupling ISO 16028:2006)
---	---	---
TC	=	coupling head, control line (male coupling ISO 5676:1983)
---	---	---
EC	=	electrical connection (female ISO 7638:2003)

ANNEX IV

Requirements applying to energy sources and energy storage devices of braking systems and trailer braking couplings and to vehicles fitted with them

1. Definitions

For the purposes of this Annex:

• 1.1. ‘hydraulic or pneumatic braking system with stored energy’ means a braking system where energy is supplied by a hydraulic fluid or air under pressure, stored in one or more energy storage devices fed from one or more pressure pumps or compressor(s) each fitted with a means of limiting the pressure to a maximum value (specified by the manufacturer).

A. COMPRESSED-AIR BRAKING SYSTEMS

1. Capacity of energy storage devices (Energy reservoirs)

1.1.   General requirements

• 1.1.1. Vehicles on which the operation of the braking system depends on the use of compressed air shall be fitted with reservoirs of a capacity meeting the requirements laid down in points 1.2 and 1.3.

• 1.1.2. However, the reservoirs shall not be required to be of a prescribed capacity if the braking system is such that in the absence of any energy reserve it is possible with the service braking system control device to achieve a braking performance at least equal to that prescribed for the secondary braking system.

• 1.1.3. When verifying compliance with the requirements laid down in points 1.2 and 1.3 the brakes shall be adjusted as closely as possible.

1.2.   Vehicles of category T

• 1.2.1. The air brake reservoirs of vehicles shall be so designed that after eight full-stroke actuations of the service braking system control device, the pressure remaining in the air brake reservoir shall be not less than the pressure required to obtain the specified secondary braking performance.

• 1.2.2. During the test, the following requirements shall be satisfied:

• 1.2.2.1. The initial pressure in the reservoirs shall be that indicated by the manufacturer. This pressure shall be such as to enable the prescribed performance for the service braking system to be achieved.  The initial pressure shall be stated in the information folder.

• 1.2.2.2. The reservoir or reservoirs shall not be replenished; in addition, the reservoir or reservoirs of auxiliary equipment shall be isolated.

• 1.2.2.3. In the case of vehicles authorised to tow a vehicle, the supply line shall be blocked off and a reservoir of 0,5 litre capacity shall be connected to the control line. The pressure in this reservoir shall be exhausted before each actuation of the brakes. After the test referred to in point 1.2.1 the pressure in the control line shall not be less than one half of the pressure obtained at the first brake application.

1.3.   Vehicles of categories R and S

• 1.3.1. Reservoirs fitted to towed vehicles shall be such that after eight full-stroke actuations of the tractor's service braking system, the pressure supplied to the operating parts using it does not fall below a level equivalent to one-half of the figure obtained at the first brake application and without actuating either the automatic or the parking braking system of the towed vehicle.

• 1.3.2. During the test, the following requirements shall be satisfied:

• 1.3.2.1. The pressure in the reservoirs at the beginning of the test shall be 850 kPa.

• 1.3.2.2. The supply line shall be blocked off; in addition, the auxiliary equipment reservoirs shall be isolated.

• 1.3.2.3. The reservoir shall not be replenished during the test.

• 1.3.2.4. At each brake application, the pressure in the control line shall be 750 kPa.

• 1.3.2.5. At each brake application, the digital demand value in the electric control line shall be corresponding to a pneumatic pressure of 750 kPa.

2. Capacity of energy sources

2.1.   General provisions

Compressors shall satisfy the requirements laid down in the following points:

2.2.   Symbols specific to this section

• 2.2.1. p1 the pressure corresponding to 65 % of the pressure p2 referred to in point 2.2.2.

• 2.2.2. p2 is the value specified by the manufacturer and referred to in point 1.2.2.1.

• 2.2.3. t1 is the time required for the relative pressure to rise from 0 to p1; t2 is the time required for the relative pressure to rise from 0 to p2.

2.3.   Conditions of measurement

• 2.3.1. In all cases the speed of the compressor shall be that obtained when the engine is running at the speed corresponding to its maximum power or at the speed allowed by the governor.

• 2.3.2. The auxiliary equipment reservoirs shall be isolated during the tests for determining the periods t1 and t2.

• 2.3.3. On vehicles constructed to tow vehicles, the towed vehicle shall be represented by an air reservoir whose maximum relative pressure p (expressed in kPa/100) is that which can be supplied through the feed circuit of the tractor and whose volume V (expressed in litres) is given by the formula p × V = 20 R (R being the permissible maximum mass, expressed in tons, on the axles of the towed vehicle).

2.4.   Interpretation of results

• 2.4.1. The time t1 recorded for the least favoured energy storage device shall not exceed:

• 2.4.1.1. three minutes in the case of vehicles to which the coupling of a towed vehicle is not authorised;

• 2.4.1.2. six minutes in the case of vehicles to which the coupling of a towed vehicle is authorised.

• 2.4.2. The time t2 for the least efficient reservoir shall not exceed:

• 2.4.2.1. six minutes in the case of vehicles to which the coupling of a towed vehicle is not authorised;

• 2.4.2.2. nine minutes in the case of vehicles to which the coupling of a towed vehicle is authorised.

2.5.   Additional test

• 2.5.1. When the vehicle is equipped with an auxiliary equipment reservoir or reservoirs with a total capacity exceeding 20 % of the total capacity of the brake reservoirs, an additional test shall be carried out during the course of which there shall be no interference with the functioning of the valves controlling the filling of the auxiliary equipment reservoir(s). A check shall be made during the course of this test that the period t3 required to bring about a rise in the pressure in the brake reservoirs from 0 to p2 is less than:

• 2.5.1.1. eight minutes in the case of vehicles to which the coupling of a towed vehicle is not authorised

• 2.5.1.2. eleven minutes in the case of vehicles to which the coupling of a towed vehicle is authorised.

• 2.5.2. The test shall be performed in the conditions prescribed in points 2.3.1 and 2.3.3.

2.6.   Tractors

• 2.6.1. Vehicles to which the coupling of a towed vehicle is authorised shall also comply with the above requirements for vehicles not so authorised. In that case, the tests in points 2.4.1, 2.4.2 and 2.5.1 shall be conducted without the reservoir mentioned in item 2.3.3.

3. Pressure test connections

• 3.1. A pressure test connection shall be fitted at the closest readily accessible position to the least efficient reservoir within the meaning of point 2.4.

• 3.2. The pressure test connections shall comply with clause 4 of ISO standard 3583-1984.

B. VACUUM BRAKING SYSTEMS

1. Capacity of energy storage devices (energy reservoirs)

1.1.   General

• 1.1.1. Vehicles on which the operation of the braking system requires the use of a vacuum shall be equipped with reservoirs of a capacity meeting the requirements laid down in points 1.2 and 1.3.

• 1.1.2. However, the reservoirs shall not be required to be of a prescribed capacity if the braking system is such that in the absence of any energy reserve it is possible to achieve a braking performance at least equal to that prescribed for the secondary braking system.

• 1.1.3. In verifying compliance with the requirements laid down in points 1.2 and 1.3, the brakes shall be adjusted as closely as possible.

1.2.   Vehicles of category T and C

• 1.2.1. The reservoirs of agricultural vehicles shall be such that it is still possible to achieve the performance prescribed for the secondary braking system:

• 1.2.1.1. after eight full-stroke actuations of the service braking system control device where the energy source is a vacuum pump; and

• 1.2.1.2. after four full-stroke actuations of the service braking system control device where the energy source is the engine.

• 1.2.2. Testing shall be performed in conformity with the following requirements:

• 1.2.2.1. The initial energy level in the reservoir(s) shall be that specified by the manufacturer. It shall be such as to enable the prescribed service-braking performance to be achieved and shall correspond to a vacuum not exceeding 90 % of the maximum vacuum furnished by the energy source. The initial energy level shall be stated in the information folder.

• 1.2.2.2. The reservoir(s) shall not be fed; in addition, any reservoir(s) for auxiliary equipment shall be isolated.

• 1.2.2.3. In the case of agricultural vehicles authorised to tow a towed vehicle, the supply line shall be blocked off and a reservoir of 0,5 litre capacity shall be connected to the control line. After the test referred to in point 1.2.1, the vacuum level provided at the control line shall not have fallen below a level equivalent to one-half of the figure obtained at the first brake application.

1.3.   Vehicles of categories R1, R2 and S1

• 1.3.1. The reservoir(s) with which towed vehicles are equipped shall be such that the vacuum level provided at the user points shall not have fallen below a level equivalent to one-half of the value obtained at the first brake application after a test comprising four full-stroke actuations of the towed vehicle's service braking system.

• 1.3.2. Testing shall be performed in conformity with the following requirements:

• 1.3.2.1. The initial energy level in the reservoir(s) shall be that specified by the manufacturer. It shall be such as to enable the prescribed service braking performance to be achieved.  The initial energy level shall be stated in the information folder.

• 1.3.2.2. The reservoir(s) shall not be fed; in addition, any reservoir(s) for auxiliary equipment shall be isolated.

2. Capacity of energy sources

2.1.   General

• 2.1.1. Starting from the ambient atmospheric pressure, the energy source shall be capable of achieving in the reservoir(s) in three minutes the initial level specified in point 1.2.2.1. In the case of a vehicle to which the coupling of a towed vehicle is authorised, the time taken to achieve that level in the conditions specified in point 2.2 shall not exceed six minutes.

2.2.   Conditions of measurement

• 2.2.1. The speed of the vacuum source shall be:

• 2.2.1.1. Where the vacuum source is the vehicle engine, the engine speed obtained with the vehicle stationary, the neutral gear engaged and the engine idling;

• 2.2.1.2. where the vacuum source is a pump, the speed obtained with the engine running at 65 % of the speed corresponding to its maximum power output; and

• 2.2.1.3. where the vacuum source is a pump and the engine is equipped with a governor, the speed obtained with the engine running at 65 % of the maximum speed allowed by the governor.

• 2.2.2. Where it is intended to couple to the vehicle a towed vehicle whose service braking system is vacuum-operated, the towed vehicle shall be represented by an energy storage device having a capacity V in litres determined by the formula:

V = 15 R

where R is the maximum permissible mass, in metric tonnes, on the axles of the towed vehicle.

C. HYDRAULIC BRAKING SYSTEMS WITH STORED ENERGY

1. Capacity of energy storage devices

1.1.   General

• 1.1.1. Vehicles on which the operation of the braking system requires the use of stored energy provided by hydraulic fluid under pressure shall be equipped with energy storage devices of a capacity meeting the requirements laid down in points 1.2 and 1.3.

Energy storage devices used as pulsation dampers in hydraulic braking systems where the prescribed service braking performance is achieved by an energy source, are not considered as energy accumulation devices in the sense of this Annex.

• 1.1.2. However, the energy storage devices shall not be required to be of a prescribed capacity if the braking system is such that in the absence of any energy reserve it is possible with the service braking system control device to achieve a braking performance at least equal to that prescribed for the secondary braking system.

• 1.1.3. In verifying compliance with the requirements laid down in points 1.2.1, 1.2.2 and 2.1, the brakes shall be adjusted as closely as possible.

1.2.   Vehicles of category T and C

• 1.2.1. Vehicles equipped with a hydraulic braking system with stored energy shall meet the following requirements:

• 1.2.1.1. After eight full-stroke actuations of the service braking system control device, it shall still be possible to achieve, on the ninth application, the performance prescribed for the secondary braking system.

• 1.2.1.2. Testing shall be performed in conformity with the following requirements:
• 1.2.1.2.1. Testing shall commence at a pressure that may be specified by the manufacturer but is not higher than the cut-in pressure.
• 1.2.1.2.2. The energy storage devices shall not be fed; in addition, any energy storage devices for auxiliary equipment shall be isolated.

• 1.2.2. Tractors equipped with a hydraulic braking system with stored energy which cannot meet the requirements of point 2.2.1.4.1 of Annex I shall be deemed to satisfy that point if the following requirements are met:

• 1.2.2.1. After any single transmission failure it shall still be possible after eight full-stroke actuations of the service braking system control device, to achieve, at the ninth application, at least the performance prescribed for the secondary braking system or, or, where performance prescribed for the secondary braking system requiring the use of stored energy is achieved by a separate control device, it shall still be possible after eight full-stroke actuations to achieve, at the ninth application, the residual performance prescribed in paragraph 3.1.4 of Annex II of this Regulation.

• 1.2.2.2. Testing shall be performed in conformity with the following requirements:
• 1.2.2.2.1. With the energy source stationary or operating at a speed corresponding to the engine idling speed, any transmission failure may be induced. Before inducing such a failure the energy storage device(s) shall be at a pressure that may be specified by the manufacturer but not exceeding the cut-in pressure.
• 1.2.2.2.2. The auxiliary equipment and its energy storage devices, if any, shall be isolated.

1.3.   Vehicles of categories R and S

• 1.3.1. If towed vehicles are equipped with energy storage devices (energy reservoirs), they shall be such that, after eight full-stroke actuations of the tractor's service braking system, the energy level supplied to the operating members using the energy, does not fall below a level equivalent to one-half of the figure obtained at the first brake application and without actuating either the automatic or the parking braking system of the towed vehicle.

• 1.3.2. During the test, the following requirements shall be satisfied:

• 1.3.2.1. The pressure in the energy storages at the beginning of the test shall be 15 000 kPa;
• 1.3.2.1.1. In case of systems using energy storage devices that are charged to a maximum operational pressure exceeding 15 000 kPa to comply with the requirements of the prescribed braking performance, the pressure in the energy storage devices at the beginning of the test shall be the maximum pressure provided for by the manufacturer.

• 1.3.2.2. The supplementary line shall be stopped; in addition, any energy storage device(s) for auxiliary equipment shall be isolated;

• 1.3.2.3. The energy storage device(s) shall not be replenished during the test;

• 1.3.2.4. At each brake application, the pressure in the hydraulic control line shall be 13 300 kPa.

2. Capacity of hydraulic fluid energy sources

The energy sources shall meet the requirements set out in the following points:

2.1.   Vehicles of category T and C

2.1.1   Symbols

• 2.1.1.1. ‘p1’ represents the maximum system operational pressure (cut-out pressure) in the energy storage devices specified by the manufacturer.

• 2.1.1.2. ‘p2’ represents the pressure after four full-stroke actuations with the service braking system control device, starting at p1, without having fed the energy storage devices.

• 2.1.1.3. ‘t’ represents the time required for the pressure to rise from p2 to p1 in the energy storage devices without application of the service braking system control device.

2.1.2.   Conditions of measurement

• 2.1.2.1. During the test to determine the time t, the feed rate of the energy source shall be that obtained when the engine is running at the speed corresponding to its maximum power or at the speed allowed by the governor.

• 2.1.2.2. During the test to determine the time t, energy storage devices for auxiliary equipment shall not be isolated other than automatically.

2.1.3.   Interpretation of results

The time t shall not exceed 30 s in the case of tractors to which the coupling of a towed vehicle is not authorised.

2.2.   Tractors equipped with a hydraulic control line for towed vehicles

• 2.2.1. To determine the feed rate of the energy source the supplementary line towed vehicle simulator as prescribed in paragraph 3.6.2.1 of Annex III to this Regulation shall be connected to the coupling head of the hydraulic supplementary line of the tractor.

• 2.2.2. The test shall be performed under the following conditions:

• 2.2.2.1. The test shall be carried out at an ambient temperature between 15 °C and 30 °C.

• 2.2.2.2. The supplementary line towed vehicle simulator shall be connected to the coupling head of the supplementary line before the test with engine not running.

• 2.2.2.3. The engine speed of the tractor during the test shall be 25 % above idling speed.

• 2.2.2.4. The parking brake control of the tractor shall be fully released during the test.

• 2.2.3. With the engine running and the bleeding device fully closed, the time elapsing when the pressure at the testing port close to the female ISO 16028:2006 coupling rises from 300 kPa to 1 500 kPa shall not exceed 2,5 seconds.

2.3.   Vehicles of category R and S

If a towed vehicle using an energy storage device to assist the service braking system and such an energy storage device is recharged by the control line pressure during application of the service braking and/or by an energy source fitted on the towed vehicle, the following requirements shall be met:

• 2.3.1. The energy source shall be powered by the tractor simulator according to Appendix 2 of Annex III via the electrical connector conforming to ISO 7638:2003.

• 2.3.2. Symbols

• 2.3.2.1. ‘pR1’ represents the maximum system operational pressure (cut-out pressure) in the energy storage device specified by the manufacturer.

• 2.3.2.2. ‘pR2’ represents the pressure after four full-stroke actuations of the tractor's service braking system control device.

• 2.3.2.3. ‘tR’ represents the time required for the pressure to rise from pR2 to pR1 in the energy storage device without application of the service braking system control device of the tractor.

• 2.3.3. Conditions of measurement

During the test to determine the time tR the following requirements shall be satisfied:

• 2.3.3.1. The pressure in the energy storage device at the beginning of the test shall be the pressure ‘pR1’.

• 2.3.3.2. The service braking system shall be operated four times by the control line of the tractor simulator.

• 2.3.3.3. At each brake application, the pressure in the control line shall be 13 300 kPa.

• 2.3.3.4. Energy storage devices for auxiliary equipment shall not be isolated other than automatically.

• 2.3.3.5. The valve feeding the energy storage device by the pressure of the control line shall be closed during the test.

• 2.3.4. Interpretation of results

The time tR shall not exceed 4 min.

3. Characteristics of alarm devices

With the engine stationary and commencing at a pressure that may be specified by the manufacturer but does not exceed the cut-in pressure, the alarm device shall not operate following two full-stroke actuations of the service braking system control device.

ANNEX V

Requirements applying to spring brakes and to vehicles fitted with them

1. Construction, fitting and inspection requirements

1.1.   Definitions

For the purposes of this Annex:

• 1.1.1. ‘spring braking systems’ means braking systems for which the energy required for braking is supplied by one or more springs acting as an energy storage device;

• 1.1.2. ‘pressure’ means negative pressure if the compression of the springs is obtained by means of a vacuum device.

2. General requirements

For the purposes of this Annex, the maximum design speed is meant to be in the forward direction of the vehicle travel, unless otherwise explicitly mentioned.

• 2.1. A spring braking system shall not be used as a service braking system except under the condition specified in point 2.2. However, in the event of a failure in a part of the transmission of the service braking system, a spring braking system may be used to achieve the residual performance prescribed in point 3.1.4 of Annex II provided that the driver can graduate this action.

• 2.1.1. Spring brakes may be used as secondary braking system independently of the vehicle maximum design speed, provided that the driver can graduate their braking action and that the performance requirements of Annex II are fulfilled.

Exceptionally, in the case of vehicles with maximum design speed not exceeding 30 km/h that use spring brakes, which control is of the ON/OFF type (e.g. a knob or a switch) and do not allow the driver to graduate the braking action, as secondary braking system, the following requirements shall be met:

• 2.1.1.1. The driver shall be able to actuate the spring brakes control from own driving seat, while keeping at least one hand on the steering control.

• 2.1.1.2. The braking performance prescribed in Annex II to this Regulation shall be fulfilled.

• 2.1.1.3. The prescribed performance shall be obtained without deviation of the vehicle from its course, without abnormal vibrations and without wheel-locking.

• 2.1.2. Vacuum spring brakes shall not be used for towed vehicles.

The energy necessary to compress the spring in order to release the brake shall be supplied and controlled by the control device actuated by the driver

• 2.2. On vehicles with a maximum design speed not exceeding 30 km/h, a spring braking system may be used as a service braking system, provided that the driver can graduate its braking action.

In the case of a spring braking system used as a service braking system, the following additional requirements shall be fulfilled:

• 2.2.1. response time requirements as laid down in section 6 of Annex III;

• 2.2.2. with the spring brakes adjusted as closely as possible, it shall be possible to actuate:
• 2.2.2.1. the brake 10 times within a minute with the engine running at idle speed (brake applications distributed evenly within this period);
• 2.2.2.2. the service braking system 6 times starting with a pressure not higher than the cut-in pressure of the energy source. During this test the energy storage devices shall not be fed. In addition, any energy storage for auxiliary equipment shall be isolated.

• 2.2.3. The spring brakes shall be designed in such a way that they are not subject to failure under fatigue. Thus, the manufacturer shall provide the Technical Service with appropriate endurance test reports.

• 2.3. A small variation in any of the pressure limits which may occur in the spring compression chamber feed circuit shall not cause a significant variation in the braking force.

• 2.4. The following requirements shall apply to tractors equipped with spring brakes:

• 2.4.1. The feed circuit to the spring compression chamber shall either include an own energy reserve or shall be fed from at least two independent energy reserves. The towed vehicle's pneumatic supply line or hydraulic supplementary line may be branched from this feed line under the condition that a pressure drop in the lines mentioned above shall not be able to apply the spring brake actuators.

• 2.4.2. Auxiliary equipment may only draw its energy from the feed line for the spring brake actuators under the condition that its operation, even in the event of damage to the energy source, cannot cause the energy reserve for the spring brake actuators to fall below a level from which one release of the spring brake actuators is possible.

• 2.4.3. In any case, during re-charging of the braking system from zero pressure, the spring brakes shall remain fully applied, irrespective of the position of the control device, until the pressure in the service braking system is sufficient to ensure at least the prescribed secondary braking performance of the laden vehicle, using the service braking system control device.

• 2.4.4. Once applied, the spring brakes shall not release unless there is sufficient pressure in the service braking system to at least provide the prescribed residual braking performance of the laden vehicle as specified in point 3.1.4 of Annex II by application of the service braking control device.

• 2.5. On tractors, the system shall be so designed that it is possible to apply and release the brakes at least three times if the initial pressure in the spring compression chamber is equal to the maximum design pressure. In the case of towed vehicles with compressed-air braking systems, it shall be possible to release the brakes at least three times after the towed vehicle has been uncoupled, the pressure in the supply line being 750 kPa before the uncoupling. However, prior to the check the emergency brake shall be released. These conditions shall be satisfied when the brakes are adjusted as closely as possible. In addition, it shall be possible to apply and release the parking braking system as specified in point 2.2.2.10 of Annex I when the trailer is coupled to the tractor.

• 2.6. In the case of tractors, the pressure in the spring compression chamber at which the springs begin to actuate the brakes, the latter being adjusted as closely as possible, shall not be greater than 80 % of the minimum level of the normal available pressure.

• 2.7. In the case of towed vehicles with compressed-air braking systems, the pressure in the spring compression chamber at which the springs begin to actuate the brakes shall not be greater than that obtained after four full-stroke actuations of the service braking system in accordance with point 1.3 of Part A of Annex IV. The initial pressure is fixed at 700 kPa.

• 2.8. In case of towed vehicles with hydraulic braking systems not using stored energy to pressurise the spring compression chamber, the pressure at which the springs begin to actuate the brakes shall not be greater than 1 200 kPa.

• 2.9. In case of towed vehicles with hydraulic braking systems using stored energy to pressurise the spring compression chamber, the pressure in the spring compression chamber at which the springs begin to actuate the brakes shall not be greater than that obtained after four full-stroke actuations of the service braking system in accordance with point 1.3 of Part C of Annex IV. The initial pressure is fixed at 12 000 kPa. In addition, the pressure in the supplementary line at which the springs begin to actuate the brakes shall not be greater than 1 200 kPa.

• 2.10. When the pressure in the line feeding energy to the spring compression chamber — excluding lines of an auxiliary release device using a fluid under pressure — falls to the level at which the brake parts begin to move, an optical or audible warning device shall be actuated. Provided this requirement is met, the warning device may comprise the warning signal specified in point 2.2.1.29.1.1 of Annex I. This provision does not apply to towed vehicles.

• 2.11. If a tractor authorised to tow a vehicle of category R and S with a continuous or semi-continuous braking is fitted with a spring braking system, automatic application of the said system shall cause the application of the towed vehicle's brakes.

• 2.12. Towed vehicles which utilise the compressed-air service braking system energy reserves to fulfil the requirements for the automatic brake as laid down in point 3.2.3 of Annex II shall also fulfil one of the following requirements when the towed vehicle is uncoupled from the tractor and the towed vehicle park brake control device is in the released position (spring brakes not applied):

• 2.12.1. when the energy reserves of the service braking system reduce to a pressure no lower than 280 kPa the pressure in the spring brake compression chamber shall reduce to 0 kPa to fully apply the spring brakes. This requirement shall be verified with a constant service braking system energy reserve pressure of 280 kPa;

• 2.12.2. a reduction in the pressure within the service braking system energy reserve results in a corresponding reduction in the pressure in the spring compression chamber.

3. Auxiliary Release System

• 3.1. A spring braking system shall be so designed that, in the event of a failure in that system, it is still possible to release the brakes. This may be achieved by the use of an auxiliary release device (pneumatic, hydraulic, mechanical, etc.).

Auxiliary release devices using an energy reserve for releasing shall draw their energy from an energy reserve which is independent from the energy reserve normally used for the spring braking system. The pneumatic or hydraulic fluid in such an auxiliary release device may act on the same piston surface in the spring compression chamber which is used for the normal spring braking system under the condition that the auxiliary release device uses a separate line. The junction of this line with the normal line connecting the control device with the spring brake actuators shall be at each spring brake actuator immediately before the port to the spring compression chamber, if not integrated in the body of the actuator. This junction shall include a device which prevents an influence of one line on the other. The requirements laid down in point 2.2.1.5 of Annex I also apply to this device.

• 3.1.1. For the purposes of the requirement laid down in point 3.1, components of the braking system transmission shall not be regarded as subject to failure if they are not regarded as liable to breakage in accordance with point 2.2.1.2.7 of Annex I, provided that they are made of metal or of a material having similar characteristics and do not undergo significant distortion in normal braking.

• 3.2. If the operation of the auxiliary device referred to in point 3.1 requires the use of a tool or spanner, that tool or spanner shall be kept on the vehicle.

• 3.3. Where an auxiliary release system utilises stored energy to release the spring brakes the following additional requirements shall apply:

• 3.3.1. Where the control device of the auxiliary spring brake release system is the same as that used for the secondary or parking braking system, the requirements laid down in point 2.4 shall apply in all cases.

• 3.3.2. Where the control device for the auxiliary spring brake release system is separate to the secondary or parking braking system control device, the requirements laid down in point 2.3 shall apply to both control systems. However, the requirements laid down in point 2.4.4 shall not apply to the auxiliary spring brake release system. In addition, the auxiliary release control device shall be located so that it is protected against application by the driver from the normal driving position.

• 3.4. If compressed air is used in the auxiliary release system, the system should be activated by a separate control device, not connected to the spring brake control device.

ANNEX VI

Requirements applying to parking braking systems equipped with a mechanical brake-cylinder locking device

1. Definitions

For the purposes of this Annex:

• 1.1. ‘mechanical brake-cylinder locking device’ means a device which ensures braking operation of the parking braking system by mechanically locking the brake piston rod. Mechanical locking is effected by exhausting the compressed fluid held in the locking chamber; it is so designed that unlocking can be effected by restoring pressure in the locking chamber.

2. Requirements

• 2.1. The mechanical brake-cylinder locking device shall be designed in such a way that it can be released when the locking chamber is again subjected to pressure.

• 2.2. When the pressure in the locking chamber approaches the level corresponding to mechanical brake-cylinder locking device, an optical or audible warning system shall be actuated. This provision does not apply to towed vehicles. In the case of towed vehicles the pressure corresponding to mechanical brake-cylinder locking device shall not exceed 4 kPa. It shall be possible to achieve parking braking system performance after any single failure of the towed vehicle service braking system. In addition, it shall be possible to release the brakes at least three times after the towed vehicle has been uncoupled, the pressure in the supply line being 650 kPa before the uncoupling. These conditions shall be satisfied when the brakes are adjusted as closely as possible. It shall also be possible to apply and release the parking braking system as specified in point 2.2.2.10 of Annex I when the towed vehicle is coupled to the tractor.

• 2.3. In the case of brake actuators fitted with a mechanical brake-cylinder locking device, the brake actuator shall be capable of being actuated by either of two energy reserves.

• 2.4. The locked brake cylinder may only be released if it is certain that the brake can be operated again after such release.

• 2.5. In the event of a failure of the source of energy supplying the locking chamber, an auxiliary unlocking device (mechanical or pneumatic, for instance) using, for example, the air in one of the tyres of the vehicle, shall be provided.

• 2.6. The control device shall be such that, when actuated, it performs the following operations in sequence: it applies the brakes so as to provide the degree of efficiency required for parking braking, locks the brakes in that position and then cancels out the brake-application force.

ANNEX VII

Alternative test requirements for vehicles for which tests equivalent to Type-I, Type-II or Type-III tests have been carried out

1. Definitions

For the purposes of this Annex: