Spring Loaded Brake Test and Removal Brake function during operation If the truck stops and the accelerator pedal is in the neutral position, the springloaded brake automatically applies after 5-120 seconds (adjustable, set to 8 sec. as standard). “Release brake solenoid” 7Y1 is de-energised by the hydraulic controller and the pre-tension pressure is directed to the reservoir. This discharges the spring-loaded brake and the brake is activated. If the accelerator is pressed again, output 2 of the hydraulic controller 2U9/pin2 is controlled, “Release brake solenoid” 7Y1 and simultaneously toggle valve 8Y4 is set to block. The steer pump is set to maximum speed. This produces the required increase in pressure in the steering circuit to pre-tension the brake cylinder against the spring assembly. After the brakes are released, the toggle valve 8Y4, controlled by the magnetic brake switch 7S21, is restored to free flow to allow for steering without pressure loss. The pre-tension pressure is kept in the system through non-return valves. When the pressure drops below the fixed minimum level (RSP=Return switch point on the pressure switch), changeover valve 8Y4 is activated again and the pump speed increased to maximum until the holding pressure is attained again. This process lasts approx. 500ms.
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