Commission Delegated Regulation (EU) 2015/68Show full title

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 (t_f) 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:

3.6.2.1.2.1.

Nominal volume of 1 000 cm³;

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.