Steer Cylinders; Rear Axle Oscillation Lockout System; Description; Theory Of Operation - Manitowoc Grove RT880E Service And Maintenance Manual

RT880E SERVICE MANUAL
Functional Check
1. Cycle each outrigger cylinder several times. Verify each
cylinder extends and retracts properly.
2. Rear steer the crane to the left and to the right several
times. Verify the crane steers properly in both directions.
3. Check the valve and lines for leakage. Make repairs as
needed.
NOTE: For further information on the rear steer/axle lock-
out/fan drive valve, refer to Axle Lockout, Rear
Steer and Oil Cooler Fan Motor Control Manifold,
page 2-64.

Steer Cylinders

Description

The steer cylinders are mounted on the axles, two cylinders
on each axle. The barrel end of each cylinder is attached to
the axle housing and the rod end is attached to the steering
l u g o n t h e a x l e e n d . T h e c y l i n d e r s a r e c o n t r o l l e d
hydraulically by the steering control valve.
Maintenance
NOTE: For Disassembly and Assembly procedures, refer
to Steer Cylinder, page 2-88.
Removal
1. Tag and disconnect the hydraulic lines going into the
steer cylinder. Cap or plug all openings.
2. Remove the bolt, washer, and lockwasher securing each
pin weldment in the rod end and barrel end of the cylin-
der.
NOTE: Steer cylinder weighs approximately 44 lb (20 kg).
3. Remove both pin weldments and two thrust washers
(rod end only), and remove the cylinder from the axle.
Installation
1. Position the cylinder onto the attachment fittings on the
axle and install both pin weldments. On the rod end,
install a thrust washer on the top and bottom of lug.
2. Secure each pin weldment with the bolt, washer, and
lockwasher.
Grove
3. Connect the hydraulic lines to the cylinder as tagged
during removal.
4. Operate the steering system and check the cylinder for
proper operation and any leakage.
REAR AXLE OSCILLATION LOCKOUT
SYSTEM
Description
The rear axle oscillation system consists of two lockout
cylinders, a lockout valve, an axle oscillation relay, and an
area definition potentiometer (see Figure 8-11 and 8-12).
The lockout cylinders are mounted between a cradle (fifth
wheel) and the carrier frame. The lockout valve is mounted
on the left inner center frame rail and hydraulically controls
the oscillating abilities of the lockout cylinders. The axle
oscillation relay is located on the relay panel under the front
c o n s o l e c o v e r i n t h e c a b a n d t h e a r e a d e f i n i t i o n
potentiometer is located in the electrical swivel assembly.

Theory of Operation

The rear axle is mounted on a cradle (fifth wheel) allowing
maximum oscillation of 10 in (25 cm) total while traveling
over uneven terrain. Oscillation is provided only when the
superstructure is within 6 degrees left or right of directly over
the front. When the superstructure is within 6 degrees left or
r i g h t o f d i r e c t l y o v e r t h e f r o n t , t h e a r e a d e f i n i t i o n
potentiometer energizes the axle oscillation relay which in
turn energizes the solenoids on the lockout valve. When the
solenoids are energized, the valve spools are shifted to allow
hydraulic transfer between the two lockout cylinders. As one
side of the axle is forced up by traveling over uneven terrain,
the hydraulic oil flows from the rod end of cylinder A to the
barrel end of cylinder B and from the rod end of cylinder B to
the barrel end of cylinder A. The system is not pressurized
and oil is moved from one cylinder to the other by the action
of the axle moving the cylinder.
When the superstructure is more than 6 degrees left or right
of directly over the front, the area definition potentiometer
deenergizes the axle oscillation relay. This deenergizes the
solenoids on the lockout valve and allows the springs in the
valve to shift the valve spools to the closed position to
prevent hydraulic oil flow between the cylinders. By stopping
the flow of oil, a hydraulic lock is created and the axle is held
rigid in that position.
Published 11-10-2014, Control # 524-00
UNDERCARRIAGE
8-11
8