Hino 600, Workshop Manual, Page: 339 / 451

SERVICE BRAKE (FULL AIR BRAKE) BR02–61
INSPECTION
EN0680202H200007
1. PREVENTIVE MAINTENANCE
Every 3 months, 900 operating hours or 25,000 miles, whichever if
first, it is recommended that the operation and leakage checks
described in this manual be performed.
2. OPERATING CHECKS
(1) Provide a pressure gauge and drain valve at the supply side and
delivery side of the pressure protection valve being checked.
(2) Build up the air system to full pressure and shut off the engine.
(3) While watching the gauges on the supply and delivery sides of the
valve, slowly begin to exhaust pressure from the delivery side. Note
that both gauges will show pressure loss until the closing pressure of
the pressure protection valve is reached.
The pressure protection valve should close at approximately (

5 psi)
the pressure indicated on the valve's label or in the vehicle handbook.
The gauge on the delivery side of the valve should continue to show
loss of pressure while the gauge on the supply side should stop at the
same pressure as the setting of the valve.
(4) (PR-3 only) Build pressure up again and shut off engine. Slowly
exhaust air from the supply side of the PR-3. The gauge on the deliv-
ery side of the valve should remain at the highest pressure previously
attained.
3. LEAKAGE CHECKS
(1) Build up the air system to full pressure and shut off the engine.
(2) Apply a soap solution around the cap of the pressure protection valve.
A one-inch bubble in three seconds or longer is acceptable. PR-3 - No
leakage permissible at bottom of valve.
(3) Drain the air pressure from the delivery side of the pressure protection
valve and disconnect the air line to it.
(4) Apply a soap solution to the delivery port. A one inch bubble in five
seconds or more is acceptable.
4. REMOVING
(1) Block or hold the vehicle by means other than air brakes.
(2) Drain all system reservoirs individually, to 0 psi.
(3) Disconnect and identify (supply and delivery) the air lines leading to
and from the pressure protection valve.
(4) Remove the mounting bolts, if any, that secure the valve.
5. INSTALLING
(1) Re-install the mounting bolts and secure the replacement valve to the
vehicle.
(2) Reconnect the supply delivery air lines to the proper ports of the
replacement valve.
6. GENERAL
After installing a replacement valve, it is recommended that the oper-
ating and leakage checks be performed as outlined in this manual. If
the proper setting cannot be attained by moderate adjustment of the
cap, the valve may have the wrong spring and will have to be
exchanged for the correct valve. The PR-4 is not adjustable.