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ANNEX VU.K. Requirements applying to spring brakes and to vehicles fitted with them

1. Construction, fitting and inspection requirements U.K.

1.1.DefinitionsU.K.

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 U.K.

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.U.K.

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.U.K.

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.U.K.

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.U.K.

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

2.2.1.

[F1response 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.

Textual Amendments

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.U.K.

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

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.U.K.

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.U.K.

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.U.K.

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.U.K.

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.U.K.

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.U.K.

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.U.K.

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):U.K.

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 U.K.

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.).U.K.

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.U.K.

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.U.K.

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

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.U.K.