JLG 20VP (3120728) Service Manual - Manual (Page 23)

SECTION 2 - SERVICE PROCEDURES
3120728 – JLG Lift – 2-5
2.5 DRIVE MOTOR COMPONENT SERVICE
PROCEDURES
Torque Limiting Clutch Maintenance
VP Series machines are equipped with a torque limiting
clutch coupling on each drive axle. The clutch is mounted
inline on the drive axle between the drive wheel and the
drive motor gear box. The clutch is designed to slip at a
pre-set torque if the machines rear wheels are over-driven
while the machine is being towed, pushed or forklifted,
thus preventing damage to the drive gear box. Although
factory pre-set, the clutch assembly and torque should be
checked at the following interval:
• Every 3 months.
Visual Inspection and Limiting Torque
Checking Procedure
1. Locate the machine on a firm level surface.
KEEP MACHINE LEVEL OR SLIGHTLY TILTED TOWARD FORKLIFT
TRUCK WHEN LIFTING TO PREVENT MACHINE FROM SLIDING
OFF LIFTING TINES.
2. Carefully raise the lift to gain access to the under-
side of the base frame. Refer to Section 2.4, "Posi-
tioning Lift For Access to Components Located
Under the Base Frame".
3. Locate the clutch assembly on each rear drive axle
and check for the following;
a. Check the coupling chains for any loose or miss-
ing parts, i.e. pins, links, etc., replace if neces-
sary.
b. Check that the allen-head set screws on the
(large) clutch adjusting nut are in place and
secure. Tighten or replace if necessary.
c. Check for any debris wedged in or wrapped
around the clutch coupling chains and axle
shafts. Remove debris and clean area if neces-
sary.
Checking Clutch - Torque Setting (ft. lb.)
NOTE: Check that the machines brakes are engaged before
applying torque to the rear drive wheels.
1. Remove the drive wheels from the drive axles.
2. Select a torque wrench capable of setting a torque
of at least 185 ft. lb. Insert special tool (P/N-
0080229) into a 3/4" socket on the torque wrench.
3. Slide the tool onto the end of the drive axle aligning
the key on the axle shaft (install key on axle, if nec-
essary), with key slot in the tool. (See Figure 2-2.)
4. Turn the torque wrench and note the torque setting
when the torque limiting clutch releases. The torque
(slip) setting should be set at 185 ft. lb. Check both
rear drive axles.
NOTE: The allowable breaking torque for the torque limiting
clutch can be set as much as 35 ft. lb. less than the
factory setting of 185 ft. lb., but never more than the
185 ft. lb. factory setting.
5. If torque setting is OK, re-install the wheels and
lower machine, IF NOT, see the following note.
NOTE: If torque setting is outside the allowable range of
specifications, the torque limiting clutch will need
adjustment. See Torque Limiting Clutch Adjustment
following.
Figure 2-2. Check Torque Limit Clutch -
Torque Setting.
SERVICE TOOL
P/N-0080229
(REQUIRES A 1-3/4” SOCKET)
TORQUE
LIMITING
CLUTCH
LOCATION