Oshkosh JLG 400S, Service And Maintenance Manual

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SECTION 3 - CHASSIS & TURNTABLE
3120895 – JLG Lift – 3-25
3.7 DRIVE MOTOR
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.
Shaft Seal Replacement
REMOVAL
1. Remove the snap ring (1) retaining the shaft seal
and support washer.
2. Remove the support washer (2).
3. Carefully pry out the shaft seal (3).
To avoid damaging the shaft during removal, install
a large sheet metal screw into the chuck of a slide
hammer. Drive the screw into the seal surface and
use the slide hammer to pull the seal.
4. Discard the seal.
INSPECT THE COMPONENTS
Inspect the new seal, the motor housing seal bore, and
the sealing area on the shaft for rust, wear, and contami-
nation. Polish the shaft and clean the housing if neces-
sary.
INSTALLATION
1. Cover the shaft splines with an installation sleeve to
protect the shaft seal during installation.
2. Install a new shaft seal with the cupped side facing
the motor. Press seal into housing until it bottoms
out. Press evenly to avoid binding and damaging
the seal.
3. Install seal support washer.
4. Install snap ring.
5. Remove the installation sleeve.
Bias spring
Servo piston
Swashplate
Output
Shaft
Piston
Slipper
Cylinder
Block
Endcap
Shaft
Seal
Bearing
Minimum
Angle
Stop
Valve plate
Figure 3-6. Drive Motor Cross Section
1
2
3
1. Snap Ring
2. Support Washer
3. Shaft Seal
Figure 3-7. Removing the Shaft Seal