Separate Engine And Generator; Remove Coupling Assembly; Disassembly - Hobart Jet-Ex 5D Operation And Maintenance Manual

OM-2094 / Operation and Maintenance Manual
Jet-Ex 5D / Series 500285/ Generator Set

Disassembly

3.
Removal of the flexible coupling is required for servicing the generator armature, generator bearings, or
the coupling itself. To remove the coupling, for any reason, it is necessary to separate the engine and
generator. Many mechanics prefer to remove the engine and generator as an assembly, and then
separate them. Others may prefer to remove the engine or the generator separately to reach the
coupling. However, separating the engine and generator while they are installed in the ground power
unit is VERY DIFFICULT because of the limited working space.
During removal DO NOT cut any cables or wires. Disconnect cables or wires if/as necessary and tag
them for reassembly.
a. Separate Engine and Generator
(1) Remove fuel tank and canopy components.
(2) Remove the sheet metal cover from around the generator housing and the flywheel housing.
(3) Attach a hoist to the generator housing.
(4) Use a long-handled, reversible ratchet drive fitted with a 5/16-inch Allen wrench to remove the
screws which attach the flexible coupling disk to the engine flywheel.
(5) Support the rear of the engine with a jack stand.
(6) Remove the bolt and shock mount attaching the generator housing to the frame.
(7) Remove the bolts attaching the generator housing to the engine flywheel housing.
(8) Separate the generator from the engine with the hoist and move it to a clear working area.
b. Remove Coupling Assembly (Figure 3)
(1) Using a socket wrench, remove all three of the 3/8-16 X 3/4 inch screws (3) that secure the
bushing (1) to the hub of the fan and coupling assembly.
(2) To separate the bushing from the hub, lubricate two of the 3/8-16 X 3/4 inch screws and insert
them into the threaded holes (4) in the bushing. With socket wrench, screw these screws into the
bushing such that the bushing pops loose from the hub.
(3) Using a 3/16-inch Allen wrench, loosen the set screw (6) in the bushing to release pressure on
the key (5).
(4) When the bushing (1) is loose in the hub, use a mallet to GENTLY tap the bushing out of the
hub.
(5) Slide the coupling assembly off the shaft and remove the key (5).
(6) Using a 9/16-inch socket wrench, remove the screws which attach the flexible disks to the hub.
(7) Inspect the coupling assembly components carefully as follows:
a. Check for deformed fan blades and damage to the disk.
b. Check hub and split bushing for cracks, evidence of galling, and rust pits. Light rust is
permissible on the split bushing and the tapered bore of the hub.
c. Check the flexible coupling disks for warping, cracks, or worn mounting holes.
d. Check the screws which attach the flexible disks to the hub. The screws are Hobart Part No.
287935-001, which are socket head, 3/8 - 16 X 2-1/4 inch long. If they are cracked,
stretched, or have stripped threads, replace them.
NOTE: Use of the proper coupling screws and washers for replacement is very important.
Replacement screws and washers MUST be those specified above, torqued to 40 - 45
foot-pounds (54 - 61 Nm). There is NO ACCEPTABLE SUBSTITUTE for these screws or
washers.
e. Check the shaft for any damage or deformation where the coupling was mounted on it.
November 1, 2000
Revised 03/01
Chapter 3-1
Page 3