Steering System 355Service Manual – CS7000
The Steering Wheel Sensor also has an electromagnetic clutch called a “Torque Feedback Device” which
provides steering feel to the operator. The clutch consists of multiple ber discs and steel plates which are
alternately stacked. The steel plates are splined to the steering shaft so they always rotate with the shaft.
The ber discs are splined to the clutch housing and are held stationary. When electrical current ows
through the clutch eld coil winding, the magnetic eld generated pulls the plates together creating friction
between the plates and discs that resists steering wheel movement. The resistance is proportional to the
current ow. The Steering Controller regulates the amount of current ow to provide the right steering
“feel”.
Steering Actuator
Steering Actuator
The Steering Actuator consists of a motor, gear set
and a position sensor. The motor operates on three
phase AC (Alternating Current) and is a “brushless”
design. It rotates a gear set that drives the output
shaft. The output shaft is keyed to a drive gear which
drives a large “ring” gear to turn the rear drive wheel
assembly. There is also a sensor inside the motor
that reports position and rotation information to
the Steering Controller. This information provides
feedback to the controller so that it can verify that the
motor actually moved as it was commanded to.
The Steering Actuator has an internal “encoder” that
translates motor rotation information into digital
signals. The end of the motor shaft has a special
“diametrically polarized” magnet on it. The line of
separation between the north and south magnetic
poles rotates in close proximity to the encoder. The
encoder “reads” the movement of the magnetic elds
and creates a two 5v square wave signals. As the
motor rotates, one of the signals switches before the
other so that the controller can tell which direction
the motor is rotating.
Gear Set
Motor - Rotor
Motor -Stator
Encoder
Field Coil
(Inside)
Steering
Shaft
Splines
Clutch
Housing
Steel Plates and Fiber Discs
Clutch Housing
Splines to hold
Fiber Discs
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