Scrub System
44
Service Manual – Clarke CA30 20B and 17E
Scrub System (17E)
The scrub system combines the functions of the solution solenoid and the brush motor for the purpose of
limiting the solution flow only when the brush motor is active. The scrub control relay allows simultaneous,
yet isolated, control of both the low-power solution circuit and the high-power brush motor circuit. The relay
uses a low-voltage coil (24VDC) so that high-voltage power is not required in the operator’s handle for the
brush switches.
The failure modes of the scrub system include loss
of the 24VDC power supply, failure of the scrub
control relay, and to a lesser degree, failure of both
brush switches in the handle. The reason why the
switches are less likely to be the cause of the failure is
because both independent switches would have to fail
simultaneously.
•
Because the solution solenoid and brush motor
are otherwise isolated, if both are non-functional,
the likely cause is that the scrub relay has not
engaged.
•
If 24 volts is present at the scrub relay coil when
the brush switch(es) are closed, then the relay is
the cause.
•
Verify that the 24-VDC power supply is receiving
120-volt power.
•
Verify that the output of the power supply is 24
volts when receiving 120-volt supply.
24VDC
Power Supply
120 V AC
24 V DC
