112
Service Manual – SC1500
Wheel System - Traction
Functional Description
The machine is propelled by the
Drive
Wheel Assembly
which consists of a 24-
volt DC
Drive Wheel Motor
and attached
Gearbox
that drive an
11-tooth Sprocket
The
11-tooth Sprocket
drives the
Drive
Wheel Roller Chain
that drives a
15-tooth
Sprocket
connected to the
Drive Wheel
. An
adjustable
Sprocket Assembly
acts as an
idler to adjust the
Drive Wheel
Roller Chain
tension.
The
Drive Wheel Motor and Gearbox
are
fastened to the
Spacer
which is bolted to
the
Drive Wheel Frame Weldment
. The two
Axle Bearings
are fastened to the bottom
of the
Drive Wheel Frame Weldment
and
support the
Axle
and
Drive Wheel
The
Steering Roller Chain
is driven by a
sprocket connected to the steering wheel
via the steering tube assembly and two
U-joints. The
Steering Roller Chain
rotates
the
Steering Plate
and attached
Drive
Wheel Assembly
left and right to steer the
machine.
A Curtis 1210 Speed Controller provides
pulse-width modulated voltage to the
Drive Wheel Motor
to control the machine
speed. The Speed Controller will
alternate the voltage polarity to control
the machine direction.
The Operator must be standing on the
Operator Presence Pedal (referred to
as the “Dead Man Switch, S2” in the
Electrical Ladder Diagram) in order
for the drive motor to operate. With
the Operator standing on the Operator
Presence Pedal, he/she selects the
machine direction by pressing either the
Forward Drive or Reverse Drive Switch,
then depresses the Go Pedal (S5) to drive
the machine.
Note that a brake, built in to the
Drive
Wheel Motor
, will engage to hold the
machine stationary whenever the key
switch is Off or after a predetermined
time delay when the key is off and the
Go Pedal has not been pressed. When the
Go Pedal is pressed, the Speed Controller
energizes an electromagnetic solenoid to
release the brake.
Sprocket
Assembly
15-tooth
Sprocket
11-tooth
Sprocket
Drive Wheel
Roller Chain
Steering
Roller
Chain
Steering
Plate
Drive Wheel Assembly
Drive
Wheel
Axle
Spacer
Axle
Bearing (2)
Drive Wheel
Frame
Weldment
Drive Wheel
Motor and
Gearbox