TM 5-3805-255-14
0005
LOADING MECHANISM OPERATION CONTINUED
Boom Stop Positioner
0005
The boom is equipped with an air operated stop positioner system. The system will automatically stop the boom to
any preselected position of its raising arc.
Figure 8. Boom Stop Positioner.
0005
A rod is connected to the boom arm and the positioner control cam plate. When the boom control lever is pulled all
the way back into the detented RAISE position, the rod moves back and turns the cam plate as the boom raises.
Cam follower(s) on actuating lever follows cam surface. When the follower contacts the cam lobe, the actuating
lever upsets the system control valve. The compressed air from the loader's air system passes from the brake
treadle valve through the upset air valve and into the boom control spool of the main hydraulic valve. The
compressed air acts against a piston in spool assembly. The air pressure on the piston overcomes the detent
plunger spring pressure and spool centering spring returns the spool and boom control lever to the HOLD position.
Automatic Bucket Positioner
0005
The automatic bucket positioner, which is attached to the bucket cylinder, is factory preset to keep the bucket in a
horizontal or digging position, with the cutting edge of bucket parallel to the ground.
The function of the bucket positioner is to cause the bucket to return to its proper digging position automatically
after its load has been dumped and the loader is returning to the work area. After dumping, move the bucket
control lever into its detented ROLL BACK position. When the bucket reaches its preset position, it automatically
stops, and the bucket control lever moves into its HOLD position.
Adjustment. To adjust positioner for a different bucket altitude, loosen bolt securing activating cam (Figure 9).
Move bucket to desired altitude. Turn cam until cam follower on air valve actuating arm is at point in rise of cam
where air valve is actuated. Tighten bolt to secure cam in place.
END OF TASK
0005-10
