TM-5-2330-378-14-P
SEMITRAILER, LOWBED: 40 TON CONSTRUCTION EQUIPMENT TRANSPORTER M870 AND M870A1
TECHNICAL MANUAL; OPERATOR'S, UNIT, DIRECT SUPPORT AND GENERAL SUPPORT MAINTENANCE MANUAL (INCLUDING REPAIR PARTS AND SPECIAL TOOLS LIST)
JUNE 1999
TM-5-2330-378-14-P - Page 27 of 524
TM5-2330-378-14&P
1-17. AIRBRAKESYSTEM(continued).
f.
SPRING BRAKE CHAMBERS
(8) are mounted adjacent to the front and middle axle internal wheel
brakes.
The spring brake chambers (8) convert air pressure into mechanical motion to operate the slack
adjusters when applying brakes.
The spring brakes automatically
lock in the event of air-pressure
loss.
8
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29k
KU
g.
A SERVICE AIR LINE extends from the air hose coupling (tagged SERVICE) on the right side of the
semitrailer to the multifunction valve and to the relay valves.
Its purpose is to transmit changes in air
pressure originated
in the truck tractor, which cause the relay valves to function.
h.
An EMERGENCY
AIR LINE extends from the air hose coupling (tagged EMERGENCY)
on the left side
of the semitrailer
to the multifunction
valve and to the rear relay valve. This air line transmits compressed
air to fill the semitrailer
air reservoirs and maintain proper air pressure.
The multifunction
valve and the
relay valves use this air pressure to apply the brakes on the semitrailer in case of an emergency.
i.
An EMERGENCY RELAY VALVE (9) controls the service brakes on the semitrailer. It speeds brake
action by releasing air from the air reservoirs on the semitrailer
directly to the service chamber brakes.
9
0
1-13
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