178Service Manual – SC5000
34 - Scrub System, Disc
Functional Description
The disc deck is available in a 34-inch size.
The deck uses two, gear-reduced, drive motors
to drive the two brush or pad holder discs.
The scrub deck is raised and lowered using a
leadscrew actuator.
The deck also includes two removable side
squeegees that help keep the scrub water
contained within the path of the scrub deck, and
subsequently within the rear squeegee path.
Deck Lift Actuator
The deck lift actuator controls the raising and lowering of the deck, as well as the amount of pressure the
scrub disks apply to the oor.
To extend or retract the actuator, the power module reverses polarity to the actuator. The actuator
determines how long it should run to reach full extension or retraction. It accomplishes this with a pair of
cams, limit switches, and diodes.
As each cam rotates, it opens the normally closed
circuit and stops the motor’s rotation. However each
cam is functional only for its intended direction of
rotation. This is accomplished with the diodes, which
effectively short circuit the switch for one direction
(polarity), but not the other.
In the diagram below, the clockwise cam/limit
switch is effectively short circuited by its diode when
the electrical polarity is driving the motor in the
counterclockwise direction (and vice versa for the
CCW). But the counterclockwise cam is not short
circuited, so it will open the motor circuit when the
cam lobe reaches the limit switch.
The down-limit cam isn’t adjustable, but by adjusting
the position of the up-limit cam, the actuator can
control its length of travel for the leadnut along the
leadscrew.
M
CW CCW
Diodes
Limit
Switches
Up Limit
Cam
Down Limit
Cam
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