Scrub System; M2/M3 - Scrub Brush Motor Run Funcion; M5 - Scrub Brush Actuator Lit Motor Funcion; Scrub System Low-Voltage Cut-Out Funcion - Nilfisk-Advance Clarke Focus II Large Service Manual

Scrub System

Scrub System
Functional Overview
The 34 RST models use the disc-type scrub system powered by (2) 3/4 HP motor gearbox assemblies.
Note: Recovery Tank Full switch must be open (Tank empty). On all models the scrub deck platform
is raised and lowered automatically by a vertically-mounted electric lift actuator motor. The operation of the
machine's scrub functions are activated when the operator selects (presses) the scrub on (mode) panel button The
scrub pad or brush pressure ranges (1-3) are selectable allowing the operator the choice to vary the scrubbing effort
(pressure) while operating the machine Note: See the Electrical System/Main Control Programming Options
section in this manual for more detailed operation and instructions on how to change the factory default regular
scrub pressure settings
The machine's main scrub system input and output operating functions are regulated (managed) by the display
panel and combined main control board A1 The major scrub system functions are:
M2/M3 - Scrub Brush Motor Run Function
Scrub Brush Motor Circuit Overview
+ (Positive) circuit input starts with:
− A closed S3 key switch supplies the needed positive voltage to the A1 control board #J1-13 (Brn wire).
− A closed 5-amp circuit breaker (F2) supplies positive battery voltage (Brn wire) to the control side of the brush motor contactor coil (K1).
− Once the load side of K1 is closed, the needed positive battery voltage is supplied to motors M2 and M3.
- (Negative) circuit input starts with:
− Negative battery voltage is supplied to the A1 control board at terminals B1 (J1-7) Blk, B2 (J1-9) Blk, B3 (J2-9) and B4 (J2-6) Blk.
− Note: The A1 control board scrub-on button must also be depressed (enabled).
− When a palm drive switch is pressed (S6/S7), Pin 6 – Brake on the speed controller (A2) supplies negative voltage to J1-5 – For/Rev. on A1
(Red/Blk wire).
− A negative voltage output from J1-14 – Brush Contactor (Vio/Blk wire) is supplied to the K1 solenoid coil control circuit and pulls in the load
contacts on K1.
− The negative load voltage is supplied from the battery negative to motors M2 and M3.
M5 - Scrub Brush Actuator Lift Motor Function
The A1 control board outputs a controlled motor voltage polarity change (wires J2-1 and J2-8) that raises and
lowers the scrub deck for installing, removing and controlling the scrub brushes' selected current load The large
Blk negative (-) scrub brush motor wire is specially designed so that it has a known (speciied) resistance value. As
brush motor current passes through the negative wire that is, in effect, a low-value resistor, a small voltage drop
is developed across it which is proportional to the motor current This voltage change is inputted to the A1 control
board at J2-5 and J1-7 (sense wires Wht/Gra and Blk). Any surrounding temperature change in this large Neg.
motor wire affects its resistance so the temperature is sensed by a thermistor built into the control board A1 This
allows the controller to provide error correction for the temperature resistance changes When the controller senses
a current draw out of the desired range, it automatically turns on the M5 actuator motor to raise or lower the scrub
deck This process is ongoing in maintaining the operator's selected scrub motor current load setting to sustain the
desired brush working pressure
Scrub System Low-voltage Cut-out Function
The purpose of the special low battery voltage cut-out function is to help prolong battery life. The scrub deck will be
raised and the brush motors and solution solenoid valve will turn OFF automatically and cease to function when the
batteries discharge to the selected cut-out level. The cut-out level is adjustable between two settings. The standard
(S) setting (wet cell/lead-acid) is 31.34 volts or 1.74 volts per cell. The alternate (A) setting (gel/maintenance free)
is 32 63 volts or 1 81 volts per cell Note: See the Electrical System/Main Control Programming Options section in
this manual for instructions on how to select the appropriate voltage cut-out threshold.
Special Service Note: There is a minimum battery charge level that the must be reached before the low-voltage cut-out function will reset and allow
the machine to function again. On the 34 RST, the batteries must be charged to a minimum of 37.6 volts (2.09 volts per cell) in order to reset the low-
voltage cut-out function.
37 - FORM NO. 56043162 - Focus II Large