SUBSECTION 8F
BOOM HOIST PAWLS
GENERAL
This subsection contains the information necessary to re-
move, disassemble, assemble, install and adjust the boom
hoist pawls.
BOOM HOIST PAWL ASSEMBLY (2100J1008-2)
DESCRIPTION. Two pawls are provided to prevent the pos-
sibility of a "live" boom when the boom is being raised or
lowered. These pawls engage the ratchets on the boom
hoist drum assembly. One pawl prevents the boom from
falling if the planetary brake band should slip while the
boom is being lowered; the other pawl is normally engaged
and prevents the boom from falling while it is being raised
or when it is in the raised position.
With the boom hoist control lever in the neutral position, no
hydraulic pressure is applied to the pawl cylinder and only
the boom hoist pawl is engaged in the ratchet of the boom
hoist drum (see Figure 8F-3). When the boom hoist control
lever is moved by the operator to raise the boom, no hy-
draulic pressure is applied to the pawl cylinder and the
boom hoist pawl remains engaged in the ratchet of the
boom hoist drum. When the boom hoist control lever is
moved by the operator to lower the boom, hydraulic pres-
sure is applied to the pawl cylinder extending the piston and
moving the linkage to disengage the boom hoist pawl from
the ratchet of the boom hoist drum. Simultaneously the
boom hoist planetary pawl will be engaged in the ratchet of
the planetary spider.
REMOVAL. If upon inspection it is revealed that a pawl is
worn down, cracked or broken it will be necessary to re-
move the pawl and replace it. To remove the boom hoist
pawls, proceed as follows (see Figure 8F-2):
1. Lower the boom and support it on blocking. Make sure all
tension is removed from the boom hoist rope.
2. Shut down the engine and move the boom hoist lever
forward to release the boom hoist brake. With the brake re-
leased, slide pin (71) through the slot in bracket (65) and on
Figure 8F-1. Spring Bracket Assembly (2100N404)
through the drilled hole in bracket (70) as shown in Figure
8F-1. This will lock the brake in the released position
NOTE
If adequate pressure is not available to release the
3. With the engine shut down, operate a control lever until
brake, the engine will have to be started to build sys-
all hydraulic pressure is exhausted from the system.
tem pressure.
4. Disconnect and cap the hydraulic lines from the boom
Also, the assembly pin (71) may be made from 3/8
hoist brake and boom hoist planetary brake cylinders. Plug
inch steel rod stock cut to a length of 6 inches.
all connections where hydraulic lines were removed.
