Steering Systems; Description; Theory Of Operation; Rear Steering System - Manitowoc Grove RT540E Service Maintenance Manual

UNDERCARRIAGE

STEERING SYSTEMS

Description

To maximize maneuverability, the crane can be steered by
the front axle, the rear axle, or by the front and rear axles
simultaneously. The crane utilizes two separate steering
systems, one to control front axle steering and one for rear
axle steering.
Front Steering System
NOTE: Pump figures in following text are theoretical.
The front steering system consists of a hydraulic pump, load
sense steer priority flow divider valve (part of the swing
directional control valve), load sense steering control valve,
and two steer cylinders.
The hydraulic pump is driven by the engine and supplies a
hydraulic flow of 82.9 l/min (21.9 gpm) to the load sense
steering priority flow divider. The load sense steer priority
flow divider valve provides 26.5 l/min (7 gpm) to the load
sense steering control valve and the remainder to the swing
system.
When the steering wheel is turned, the load sense steering
control valve sends a load sense signal to the load sense
steer priority flow divider. As the load sense pressure
increases, the priority flow divider spool shifts to direct oil
from the hydraulic pump to the steering control valve, and to
direct oil from the L (left) port and R (right) port of the steering
control valve to the steer cylinders.

Rear Steering System

The rear steering system is controlled through a section of
the integrated outrigger/rear steer manifold and consists of
8-10
the control valve and two steer cylinders. It is activated by
the rear steer control switch located on the left armrest in the
cab.
A rear steer indicator system is provided to indicate when the
rear wheels are not centered. This system consists of an
indicator light located on the front console in the cab and a
switch located on the right side of the rear axle. When the
rear wheels are turned to the left or right, the amber indicator
light will illuminate.

Theory of Operation

Front Steering System
A hydraulic oil flow from pump number 2 flows through port 5
of the hydraulic swivel to the steer/swing directional control
valve. Regulated flow from the steer priority flow divider
valve is routed to the steering control valve upon turning of
the steering wheel and pressurizing of the load sense line.
The steering control valve routes the oil to the appropriate
ends of the front steer cylinders to turn the wheels in the
desired direction.

Rear Steering System

Hydraulic flow from pump number 1 is directed through the
integrated outrigger valve to the rear steer/outrigger
manifold. When the rear steer control switch in the cab is
positioned to steer left (push top of switch) or steer right
(push bottom of switch), a signal is sent to the directional
control valve spool, routing the supply pressure to the
appropriate ends of the rear steer cylinders to turn the
wheels in the desired direction.
Published 4-20-2015, Control # 502-01
RT540E SERVICE MANUAL