Hino 600, Workshop Manual, Page: 289 / 451

SERVICE BRAKE (FULL AIR BRAKE) BR02–11
ROADSIDE INSPECTION
In the event of a roadside inspection the system behavior will be as follows: When the system is charged to governor cut-out,
and then one reservoir drain valve is opened, initially both reservoir gauges will fall, however, the AD-IS

air dryer and reser-
voir system primary and secondary pressure protection valves will close at pressures above 70 psi, protecting the remaining
brake circuit from further loss of pressure.
TEMPORARY AIR DRYER AND RESERVOIR SYSTEM BYPASS
To temporarily bypass the air dryer, the following procedure needs to be followed:
Follow the Maintenance Precautions outlined elsewhere in this document.
Make sure that all residual pressure has been released and the air dryer purge reservoir has been drained to 0 p.s.i., then
remove the air supply line from the compressor to the inlet port (1/IN). Remove the safety valve from the AD-IS

air dryer and
reservoir system body (see Figure 1 for location). Note that a short puff of trapped air may vent from the safety valve port when
the valve is being removed. Install a T-fitting into the port. Using any adapters necessary, reinstall the safety valve in one of the
branches of the T-fitting. Using any adapters necessary, install the air supply line into the remaining T-fitting port. After testing
the T-fitting for any air leakage, by using a soap solution after charging to system cut-out pressure (a 1" bubble in 10 seconds
is acceptable), the vehicle may be returned to temporary service.
NOTICE
This is a temporary bypass of the air dryer, and full repair of the unit must be carried out at the earliest opportunity.
With the air dryer and reservoir system removed from the system, contaminants will be entering the air system: reservoirs will
need to be manually drained daily until the repairs are completed. At end of each working day, park vehicle and slowly drain
pressure through the drain valves - leave open to the atmosphere, for several hours if possible. When repairs are carried out,
be sure to check that all reservoirs (including the air dryer purge reservoir) are emptied of all contaminants.
If after bypassing the air dryer and reservoir system the system pressure still does not build, use the following procedure to
remove, clean and reinstall the delivery check valve.
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