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MHD56012 - Edition 8 11
General Disassembly
The following instructions provide necessary information to
disassemble, inspect, repair, and assemble the hoist. Hoist
assembly parts drawings are provided in “PARTS” section.
If a hoist is being completely disassembled for any reason, follow
the order of the topics as they are presented. It is recommended
that all maintenance work be performed on a bench.
In the process of disassembling the hoist, observe the following:
1. Never disassemble hoist any further than is necessary to
accomplish needed repair. A good part can be damaged
during the course of disassembly.
2. Never use excessive force when removing parts. Tapping
gently around the perimeter of a cover or housing with a soft
hammer, for example, is sufficient to break the seal.
3. Do not apply heat to a part to free it for removal unless part
being heated is already worn or damaged beyond repair and
no additional damage will occur to other parts. In general, the
hoist is designed to permit easy disassembly and assembly.
Use of heat or excessive force should not be required.
4. Keep work area as clean as practical, to prevent dirt and other
foreign matter from getting into bearings or other moving
parts.
5. When grasping a part in a vise, always use leather-covered or
copper-covered vise jaws to protect the surface of the part
and help prevent distortion. This is particularly true of
threaded members, machined surfaces and housings.
6. Do not remove any part which is press fit in or on a
subassembly unless removal of that part is necessary for
repairs or replacement.
Hoist Disassembly
Brake Disc Replacement
1. Unscrew U-nuts (40). Remove wheel cover (38).
2. Lift hand chain guides (35) off stay bolts on side plate 1 (1).
Remove hand chain (46) from handwheel (31).
3. Remove cotter pin (34), unscrew pinion nut (33) and remove
washer (32).
4. Remove handwheel (31) by holding load chain (46) and
rotating handwheel (31) counterclockwise until it can be
lifted off pinion shaft (13).
5. Remove brake cover (30) and brake disc A (27).
6. Remove ratchet gear (29) and brake disc B (28).
Overload Clutch Disassembly
1. Refer to previous instructions for removal of wheel cover
(38).
2. Use a small punch to bend tab on washer (81) out of slot in
nut (82).
3. Firmly grip outside of overload clutch assembly then use
clutch adjusting socket part number 71112064 to remove nut
(82) from supporter (78).
4. Separate remaining parts of overload clutch assembly.
Cleaning, Inspection and Repair
Use the following procedures to clean, inspect and repair
components of the hoist.
Cleaning
Clean all hoist component parts in an acid free solvent (except for
brake discs). Use of a stiff bristle brush will facilitate removal of
accumulated dirt and sediments on gears and frames. Dry each
part using low pressure, filtered compressed air.
Inspection
All disassembled parts should be inspected to determine their
fitness for continued use. Pay particular attention to the following:
1. Inspect all gears for worn, cracked, or broken teeth.
2. Inspect shafts for ridges caused by wear. If ridges caused by
wear are apparent on shafts, replace shaft.
3. Inspect all threaded items and replace those having damaged
threads.
4. Measure thickness of brake discs. If brake discs do not have
uniform thickness or are less than 5/64 in. (2 mm) thick
replace brake discs.
Repair
Actual repairs are limited to removal of small burrs and other
minor surface imperfections from gears and shafts. Use a fine
stone or emery cloth for this work.
1. Worn or damaged parts must be replaced. Refer to applicable
parts listing for specific replacement parts information.
2. Inspect all remaining parts for evidence of damage. Replace
or repair any part which is in questionable condition. The
cost of the part is often minor in comparison with the cost of
redoing the job.
3. Smooth out all minor nicks, burrs or galled spots on shafts,
bores, pins and bushings.
4. Examine all gear teeth carefully, remove nicks and burrs.
5. Polish edges of all shaft shoulders to remove small nicks
which may have been caused during handling.
6. Remove all nicks and burrs caused by lockwashers.
Hoist Assembly
• The brake will not operate properly if there is too much oil
on brake discs (27 and 28). Excessive oil or grease on brake
components could cause load to slip.
1. Dip replacement brake discs (27 and 28) in ISO VG32
hydraulic oil or SAE 10 oil for two seconds. Wipe off excess
oil.
2. Place brake disc B (28) over hub (26). Brake disc B (28) has a
smaller outside diameter than brake disc A (27).
3. Install ratchet gear (29) on hub (26) so recessed face fits over
brake disc B. Teeth of ratchet gear (29) must engage pawl
(24). Ratchet gear (29) should not rotate counterclockwise
and should “click” when rotated clockwise.
4. Place brake disc A (27) on ratchet gear (29).
5. Place brake cover (30) over stay bolts on side plate 1
assembly (1).
6. With brake surface of handwheel (31) towards brake disc A
(27), place handwheel (31) on pinion shaft (13). Rotate
handwheel (31) clockwise until clicking occurs. Hold load
chain (47) if necessary.
7. Place washer (32) over pinion (13). Install pinion nut (33)
and cotter pin (34) using “Brake Adjustment.”