JLG 660AJ Service Manual - Manual (Page 59)

SECTION 3 - CHASSIS & TURNTABLE
3121616 – JLG Lift – 3-15
3.3 FREE WHEELING OPTION
Disengage Drive Motors and Brakes for Towing, etc.
(Free Wheel)
1. Chock wheels securely if not on flat level surface.
2. Disconnect both drive hubs by inverting disconnect
caps in center of hubs.
3. If equipped, move steer/tow selector valve to float (tow)
position by pulling valve knob out.
Engage Drive Motors and Brakes (Normal
Operation)
1. If equipped, move steer/tow valve to steer position by
pushing valve knob in.
2. Connect both drive hubs by inverting disconnect cap in
center of hub.
3. Remove chocks from wheels as required.
Figure 3-15. Disconnecting Drive Hubs
3.4 DRIVE MOTOR
Description
Drive motors are low to medium power, two-position axial pis-
ton motors incorporating an integral servo piston. They are
designed for operation in open and closed circuit applications.
The standard control is a direct acting single line hydraulic
control. The integral servo piston controls motor displace-
ment.
Motors are spring biased to maximum displacement and
hydraulically shifted to minimum displacement. Minimum 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.
Figure 3-16. Drive Motor Cross Section


 





   
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Bias spring
Servo piston
Swashplate
Output
Shaft
Piston
Slipper
Cylinder
Block
Endcap
Shaft
Seal
Bearing
Minimum
Angle
Stop
Valve plate