Steering Fluid - The fluid for the steering system is supplied from the main hydraulic oil tank.
Steering System (Front) - The power for the front axle steering box (1) is provided by an engine-driven pump. The steer-
ing wheel (2) is mechanically connected to the steering box. The steering box is mechanically linked to the front wheels.
When the steering wheel is rotated, the actuating valves in the steering box open. Pressurized fluid is applied to one end of
the steering box piston, causing it to move the sector shaft and pitman arm (3). The pitman arm is mechanically linked to
the drag link (4). The drag link moves the steering mechanism (5) on the front axle to the left or right, causing the machine
to steer in the same direction. In the event of a total failure of the hydraulic system, mechanical control is retained, though
the physical effort required by the operator to steer the machine is increased.
Steering System (Rear) - The rear wheels can also be steered. When the operator selects 4-wheel steer or crab steer, the
rear wheels will be steered using pressurized oil in a steering cylinder (6) that is electronically operated. In the case of 4-
wheel steering, when it is selected in the cab, as the driver turns the steering wheel, electronic sensors will detect the
movement of the front wheels, which in turn supply via an Electronic Control Unit (ECU) a signal to the valves in the sup-
ply to the rear axle steering cylinder. The cylinder is mechanically connected to the rear axle steering mechanism that will
cause the wheels to steer. In 4-wheel steer, the rear wheels will steer in the opposite direction, but to the same degree as
the front wheels. With crab steer, the same principles apply, except the rear wheels will steer in the same direction and to
the same degree as the front wheels.
Figure 7. Steering System