TM 5-4220-233-14
Figure 1-4. Servicing Unit Flow Schematic, Sheet 2.
b.
Trailer Assembly. The trailer assembly is used to transport the body assembly to the point of usage.
Major items on the trailer include a chassis frame, axle assembly, brake system, electrical system, swivel jacks,
and tool box.
(1) Chassis Frame. The chassis frame is made of steel and contains the provisions for mounting the trailer
components and the body assembly. The chassis also contains four tiedown/lifting provisions used to secure
the complete Servicing Unit.
(2) Axle Assembly. The trailer utilizes a single axle design with leaf spring suspension. The axle is a square
beam design and contains provisions for the mounting of the hub bearings, brakes, and wheel assemblies.
(3) Brake System. The trailer utilizes a hydraulic brake system. The system consists of a drawbar surge
actuator and drum brakes on each wheel. The trailer also contains a hand actuated mechanical parking brake
system that actuates the drum brakes. When the prime mover slows or stops the weight of the trailer In the
forward direction applies the force necessary to actuate the surge actuator mounted on front of the trailer
drawbar. The surge actuator acts as the master cylinder and provides hydraulic pressure to the brake
assemblies. The surge actuator also contains the toweye provisions for connecting the trailer assembly to the
prime mover.
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