JLG 600A_AJ Service Manual - Manual (Page 80)

SECTION 3 - CHASSIS & TURNTABLE
3-30 – JLG Lift – 3121201
3.6 DRIVE MOTOR - 2WD (PRIOR TO S/N
81836)
Shaft Seal Replacement
Lip type shaft seals are used an the drive motors. These
seals can be replaced without major disassembly of the
unit. However, replacement of the shaft seal requires
removal of the pump or motor from the machine.
1. Remove the retaining ring from the housing.
Carefully remove the seal from the housing bore. The face
of the seal may be punctured with a sharp instrument
(such as a screw driver) to aid in prying the seal out, or a
slide hammer type puller may be used to remove the seal.
Care must be taken not to damage the housing bore or
shaft. Once removed the seal ia not reusable.
Prior to installing the new seal, inspect the sealing area on
the shaft for rust, wear, or contamination. Polish the seal-
ing area on the shaft if necessary.
Wrap the spline or key end of shaft with thin plastic to pre-
vent damage to the seal lip during installation. Lubricate
the inside diameter of the new seal with petroleum jelly.
NOTE: The outside diameter of the seal may be lightly
coated with a sealant (such as Loctite High Perfor-
mance Sealant #59231) prior to installation This will
aid in preventing leaks caused by damage to the
housing seal bore.
Slide the new seal over the shaft and press it into the
housing bore. Be careful not to damage seal. A seal
installer tool can be made to aid in installing the seal.
Reinstall the seal retaining ring.
3.7 DRIVE MOTOR (S/N 81836 TO PRESENT)
Description
The drive motors are low to medium power, two-position
axial piston motors incorporating an integral servo piston.
They are designed for operation in both open and closed
circuit applications. The standard control is a direct acting
single line hydraulic control. The integral servo piston con-
trols motor displacement.
The motors are spring biased to maximum displacement
and hydraulically shifted to minimum displacement. Mini-
mum and maximum displacement can be set with fixed
internal stops. The large diameter servo piston allows
smooth acceleration and deceleration with relatively large
circuit orificing.
Bias spring
Servo piston
Swashplate
Output
Shaft
Piston
Slipper
Cylinder
Block
Endcap
Shaft
Seal
Bearing
Minimum
Angle
Stop
Valve plate
Figure 3-18. Drive Motor Cross Section