PLS FLATRACK (FR). -726280064

TM 9-2320-364-20-1

1-22. PLS TRAILER (PLST) (CONT).

b. Parking Brakes. Spring chamber parking brakes are provided on all PLST axles. The application and release

of the six PLST spring brakes is controlled by a spring brake control valve. An absence of air pressure in the

emergency/spring brake supply line causes the spring brake control valve to activate the spring brakes. The spring

brake control valve also retains air pressure in the PLST air reservoir so the PLST spring brakes can be released by the

spring release valve. The spring brake control valve also prevents compounding of pressures in the brake chambers

by relieving the pressure on the spring brake side of the chambers when the spring brakes are set and the service

brakes are applied. The PLST spring brake release valve is located on the right front corner of the trailer. This valve

releases the PLST spring brakes without a prime mover air supply when there is sufficient air reservoir pressure.

After the spring brakes have been released, they can be reapplied by actuating the release valve. When air is supplied

through the emergency/spring brake supply line, the spring release valve is over-ridden and the trailer spring brakes

are released. If there is insufficient air reservoir pressure to release the trailer parking brakes, a cage nut release is

provided on each spring chamber to mechanically release the spring brakes.

c. Emergency Brakes. Whenever there is a loss of pressure from the truck or PLST air reservoir, the emergency

brakes are activated.

1-23. PLS FLATRACK (FR).

Figure 1-29. Palletized Load System Flatrack (FR)

The Flatrack (FR) (1, Figure 1-29) accommodates a 33,000 lb (15 metric tons) nominal payload during all modes of

transportation and during all specified load/unload operations. The FR is designed to withstand the dynamic and

static loads imposed while fully loaded during LHS load/unload operations. The FR has an empty weight of

3250 lb (1474 kg) without sideboards. The FR can accommodate palletized, break bulk and 20 ft (6.1 m) ISO

container payloads. Tiedowns (2) and sideboards (3) are used to contain and hold cargo. Refer to

TM 9-3990-206-14&P for Unit, Direct Support and General Support Maintenance for the PLS Flatrack.