TM 9-2330-388-14
1.
Push crank IN for low speed operation.
(2) Remove nut and the release tool from
mounting hole in the fail-safe unit.
2.
Pull crank OUT for high speed operation.
(3) Remove plug.
(4) Insert the release tool into the hole and
c.
Close the drain valves on front and rear reservoir
turn 1/4-turn to seat release tool in pressure plate.
(5) Install nut on release tool, and tighten
tanks, fig. 2-2. Open the shut-off valves on the air lines
until 2-1/2 to 2-3/4 inches of release tool is exposed.
of the towing vehicle.
(6) Repeat steps (2) through (5) for
d.
remaining fail-safe units.
Plug the intervehicular cable into receptacle, fig.
(7) As soon as air is available to refill the
2-1. Operate lights from towing vehicle to make sure
reservoirs, remove the release tool and nut from each of
that all semitrailer lights are working properly.
the four fail-safe units, and install in mounting hole.
Install plugs in place.
e.
Release the landing gear operating crank from
its clip and engage the crank on its shaft, fig. 2-3. When
there is no load, pull out on the crankshaft to engage
2-5.
Operating Towing Vehicle With Semitrailer
high-speed gears for fast raising or lowering of the
Coupled
telescoping legs. When greater power is needed, push
in on the operating shaft to engage the low-speed gears
a.
Driving. The overall length of the towing vehicle
to lower or raise the legs. Rotate the crank clockwise to
and semitrailer must be kept in mind when passing other
raise the landing gear legs. Replace crank in clip.
vehicles and when turning. Because the unit is hinged in
the middle, turning and backing are affected. The surge
3.
Rotate crank counterclockwise to lower landing
of the load also affects stopping.
gear legs.
c.
Stopping. In normal operation, the brakes of the
4.
Rotate crank clockwise to raise landing gear
towing vehicle and those of the semitrailer are applied at
legs.
the same time. Brake pressure should be applied
gradually and smoothly. On steep grades and slippery
f.
If coupling to an M931A1 or M932A1 towing
surfaces, the semitrailer brakes should be applied first;
vehicle, secure sand shoes in a swing-a-way position
then the brakes of the towing vehicle should be applied.
rearward to the semitrailer, using chain assembly
This procedure will reduce the possibility of the
provided.
semitrailer "jack-knifing".
g.
If ground boards were used, stow them in their
CAUTION
brackets at each side of semitrailer.
Never use the air brakes on the semitrailer
2-4.
Manual Release of Fail-Safe Brake
when parking if the brake drums are hot. The
brake drums will contract (shrink) as they
Manual Release - Caging - fig. NO TAG To
cool and may crack as the applied brakes
manually release the fail-safe brakes when no air is
prevent normal contracting.
available use the following procedures:
d.
Parking.
When the towing-vehicle-with-
semitrailer combination is to be parked and left
unattended, set the emergency control valve.
2-6.
Uncoupling Semitrailer From Towing Vehicle
a.
If the semitrailer is to be uncoupled in mud,
sand, or snow, or if the towing vehicle is an M931A1 or
M932A1, position ground boards approximately centered
beneath landing gear shoes.
b.
Close shut-off valves on the service and
emergency air lines at the rear of the towing vehicle.
Uncouple the two air brake hoses from the air brake
Figure 2-4. Manual Release of Fail-Safe Brake
The
semitrailer brakes will set automatically when the
(1) Block wheels to prevent semitrailer
emergency air
movement.
2-3