Figure 1-23. Overload Shutdown -726280059

TM 9-2320-364-20-1

Figure 1-23. Overload Shutdown

d. Overload Shutdown. The crane is provided with an overload shutdown (Figure 1-23) which precludes

structurally overloading. Two block and overload conditions are sensed through line-pull of the hoist. A

preprogrammed micro-processor that is constantly comparing boom angle, boom length and hoist line pull activates

solenoid valves in the telescope out, lift up, lift down and hoist up circuits when the unit is overloaded or two-blocked.

During an overload condition, the crane's function cease. Hoist down, telescope in and swing in either direction can

be used manually to bring the crane to a safe position.

Figure 1-24. Hoist, Swing Drive and Brake

e. Hoist. The crane provides vertical lift of a 3,900 lb (1769 kg) load at 22.5 ft (6.86 m) by means of a

hoist (1, Figure 1-24) with a 5.8 cu. in. (95 cu. cm.) motor. The hoist is controllable by manual control at the fixed

operators station, or at the remote control. The hoist has a spring applied, hydraulically released multi-disc pack

brake, hydraulically coupled to the hoist circuit, which applies automatically when the hoist control is released.

f. Swing Drive and Brakes. The swing drive (2) is a planetary gear box driven by a hydraulic motor to give a

swing speed on 0.8 rpm. Mechanical stops limit the rotation to 180 degrees. The swing brake (3) is a spring applied,

hydraulically released multi-disc pack, hydraulically coupled to the swing circuit, applying automatically when the

swing control is released.

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