5-12
Published 11/26/2014, Control # 447-05
HOIST AND COUNTERWEIGHT RT770E
IDLER DRUM AND CABLE FOLLOWER
Description
The main and auxiliary hoists (Figure 5-6) are each
equipped with an idler drum on the forward side of the hoist.
The main hoist idler drum is used to keep the hoist cable
from coming in contact with the boom. When the crane is
also equipped with an auxiliary hoist, the idler drum on the
auxiliary hoist is used to keep the hoist cable from coming in
contact with the main hoist. The cable follower is mounted on
the forward side of its respective hoist. The cable follower
applies a downward spring pressure against the cable onto
the hoist drum, to ensure that the cable will be uniformly
wound onto the hoist drum, and also prevent cable from
jumping under abnormal line conditions.
Maintenance
Idler Drum
Removal and Disassembly
1. Remove the bolt and end cap from the right side of the
idler roller Figure 5-6.
2. Support the idler roller and withdraw the shaft from the
left side. Take care not to lose the shim(s) on each end.
3. Remove the roller from between the side plates.
Cleaning and Inspection
1. Clean all rust and dirt from the shaft.
2. Inspect the shaft and roller for cracks, scoring, or
grooving. Replace if necessary.
Assembly and Installation
1. Position the roller between the side plates with at least
one shim on each end.
2. Install the shaft through the left side plate and the roller
and shims. Ensure the flat on the shaft end aligns with
the stop welded on the side plate.
3. Apply Loctite 243 to the bolt threads. Secure the shaft to
the right side plate with a bolt and end cap.
Cable Follower
Removal and Disassembly
1. Loosen the adjusting nuts and remove the tension
spring and adjusting rod from both sides of the hoist
Figure 5-6.
2. Remove the tack welds from the bolt heads securing the
arm to the cable follower roller.
3. Support the cable follower roller and remove the bolts
and washers securing the arms to the angles on each
end of the roller. Remove the cable follower roller.
4. Disassemble the cable follower roller as follows.
a. Remove the two bolts and washers securing the
angle to the right side of the shaft.
b. Remove the shims and roller from the shaft.
c. If necessary, remove the bearing and bearing
housing from both ends of the roller.
5. Remove the bolt and locknut securing the arm to the
spring attaching lever on each side of the hoist. Remove
arms and levers from the side plates.
NOTE: Be sure to mark each arm and lever as to what side
(left or right) they were removed from. This will be
helpful during installation.
6. Remove the grease fittings from the bushing on each
side plate.
Cleaning and Inspection
1. Clean all grease from the shaft, bearing, and roller.
2. Check the shaft, roller, and bearings for cracks, scoring,
or grooving. Replace if necessary.
3. Check the spring tension. If the springs will not provide
sufficient tension when adjusted, replace them.
Assembly and Installation
1. Install a grease fitting in the bushing on each side plate.
2. Install the left arm through the bushing on the left side
plate. Apply Loctite 243 to the bolt threads. Install left
spring attaching lever on the arm and secure with a bolt
and locknut.
3. Repeat step 2 on the right side.
4. Assemble the cable follower roller as follows.
a. Apply high strength retaining compound Loctite 680
to the bearing housings and the bearings. Install
them in both ends of the roller.
b. Install the shaft into the roller with a least one shim
on each end.
c. Apply Loctite 243 to the bolt threads. Position the
angle on the right side of the shaft and secure with
two bolts and washers.
5. Position the cable follower roller on the arms and secure
with four bolts and washers. Center the roller between
the hoist drum flanges and tighten the bolts. Tack weld
the bolt heads.
6. Attach one end of the tension springs to the levers on
each side. Install the adjusting rod through the lug on
each side plate and connect to the other end of the
spring. Install the adjusting nuts on each rod and tighten
enough to take the slack out of the springs.
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