Volvo D12, Operator'S Manual

Page: 151 / 214

Maintenance 147
Check Valves
Before working on or inspecting the ve-
hicle, set the parking brakes, place the
transmission in neutral and block the
wheels. Failure to do so can result in un-
expected vehicle movement and can
cause serious personal injury or death.
Follow the procedure below to check out
the air tank check valves at least once a
year. This is to see if air pressure is main-
tained in the tanks when the air pressure is
depleted in the supply tank (wet tank).
NOTE! The check valves should be
checked at least once per year.
1 Chock the rear wheels.
2 Let the compressor build up air pres-
sure to the governor cut-off.
3 Bleed the air pressure from the supply
tank (wet tank).
4 Check the air pressure gauges on the
instrument panel to see if the pressure
is maintained in both primary and sec-
ondary air tanks.
5 Any bleed-off from one or both of the
tanks indicates a defective check
valve; replace valve.
6 Repressurize the system and remove
the wheel chocks.
WARNING
To prevent personal injury, always drain
the air supply from the vehicle before
attempting to repair or replace a compo-
nent. Wear eye protection and take care
not to get fingers caught in the slack ad-
justers when spring brakes are applied.
Compressed air components can separate
violently during disassembly if air pres-
sure is present. Before servicing any part
of the brake air system, completely re-
lease the air pressure. Failure to do so
can result in serious personal injury or
death.