Kalmar Ottawa t2, Maintenance Manual

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5.2 Steering System – 5 Steering 59
Maintenance Manual Ottawa T2 4x2
mm mm mm mm mm mm
5 Steering
5.2 Steering System
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Description (Power Steering Components)
The standard power steering system uses an integral power
steering gear and the transmission-mounted hydraulic pump.
The system operates on fluid drawn from the common reservoir
shared with the boom and cab tilt systems.
Integral Power Steering Gear — When the steering wheel is
turned, force is transmitted from the steering wheel to the steer-
ing gear input shaft. A torsion bar pinned at one end to the input
shaft and at the other end to the worm shaft, turns with the input
shaft and exerts a rotational force on the worm shaft. In re-
sponse to this rotational force, the worm shaft, acting through
the recirculating ball mechanism, moves the rack piston axially
through the gear-housing cylinder bore.
The rack piston’s axial movement is resisted by its engagement
to the sector shaft, which is connected by linkage to the steered
wheels. Because of this resistance, the input shaft actuates the
control valve and twists the torsion bar. Pressurized fluid direct-
ed by the control valve, assists in moving the rack piston axially
through the cylinder bore. The rack piston then turns the sector
shaft to steer the vehicle.
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Description (Optional Hydrostatic Steering
Components)
Hydrostatic steering consists of an orbital control valve, a hy-
draulic pump (either engine mounted or mounted via a PTO on
the transmission), steering cylinders, a reservoir and fluid lines.
The orbital control valve has a steering wheel attached; the
steering cylinders are attached to the front axle and connected
to the steered wheels.
The orbital control valve is made up of two sections: the control
valve section and the metering section. The control valve sec-
tion directs fluid to and from the metering section and the steer-
ing cylinders, and regulates the pressure to the steering
cylinders. The control valve section is made up of a mechani-
cally actuated spool valve and pressure chambers to provide
circuit isolation. The metering section controls the amount of
fluid to the steering cylinders while maintaining the relationship
between the steering wheel and the steered wheels. This sec-
tion can also act as a manual pump providing manual steering
in the event of an inoperable hydraulic pump. The metering
section consists of a rotor that orbits within a fixed stator to
force oil through the section, and a commutator to channel the
fluid to the valve section.