Note: no liability can be accepted for the accuracy of this page

1. Create 20-21 in. Hg. vacuum in the brake pipe and move the driver’s brake pipe handle to the ‘LAP’ position.

2. Operate each passenger communication valve and endure there is an immediate destruction of vacuum in the brake pipe system and the brakes have applied. Chain operated valves must be tested for stability of the chain by pulling the chain from the furthermost point from the valve. The operating force should not exceed 35 lbf vertical pull.

3. Check that all types of valve can be reset with reasonable ease and on completion of the test they are correctly set to the normal running (closed) position. Valves are reset as follows:-

Lever type - Insert a carriage key into  the valve spindle and turn in a clockwise direction until the lever is almost vertically positioned.

Plunger type - Pull the knurled plunger against the spring pressure until the valve is heard to reset.

Body End type - Turn the identification disc on the body end outside the vehicle to the horizontal position.

If the pull on the chain exceeds 35 lbf or valves are stiff, lubricate in accordance with MAINTENANCE PROCEDURE 3-06.