Scrub Brush System; Functional Overview - Nilfisk-Advance Hydro-Retriever 3800 Service Manual

SCRUB BRUSH SYSTEM

FUNCTIONAL OVERVIEW

• Disc Brush System Overview
See Figure 3. The machines Hydro-Retriever ™ 3800 and BR 1100 (model #'s 56411000 & 56411002) use the disc type scrub system. A single
3HP 36V DC permanent magnet motor is connected at both ends with (2) 90-degree gearboxes that drive the two 20" disc (rotary) brushes.
• Cylindrical Brush System Overview
See Figure 8. The machine models Hydro-Retriever ™ 3800C, BR 1100C (#'s 56410350 & 56410351) and models 2042, BR 1100C-XL (#'s
56410001 & 56410425) use two cylindrical brushes that counter rotate to sweep up light debris and scrub at the same time. Each scrub brush
is powered on opposing ends by 1 HP permanent magnet motors attached to separate poly-V belt/pulley drives.
• General Brush Overview
On all models the scrub deck platform is raised & 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) either the normal or heavy scrub (mode) panel buttons. The scrub
pad or brush pressure ranges (normal & heavy) are independently programmable allowing the operator the choice to vary the scrubbing effort
(pressure) while operating the machine. Note: See the Main Control Board Special Program Options section in this manual for more detailed
operation and instructions to change scrub pressure settings.
See Figure 1. The machine's main scrub system input and output operating functions are regulated (managed) by the membrane switch display
panel A4 and main control board A3. The major scrub system functions are...
• Scrub Brush Motor Run Function
To turn On (energize) the K3 brush motor solenoid either the normal or heavy scrub button (location A4 panel) must be pressed and the drive pedal
moved off its neutral position triggering an output from the A2 electronic throttle. These two-operator functions deliver the required A3 control board
and A1 speed control circuit inputs.
Detailed Explanation of the scrub motor function
A closed A4 membrane panel switch input (either normal or heavy) enables the A3 microprocessor automatic functions for the brush lift, brush
solenoid, solution solenoid, vacuum solenoid and squeegee lift. The next step is the movement of the foot pedal for the needed A2 throttle output
to the A1 speed controller, which causes either FWD or REV motor action. At the moment of A2 throttle input the A1 controller closes an internal
coil driver and outputs a POS. 36V signal from pin #8 (wire color Brn/Wht) to the A3 J2 pin #6 connection. This input signal causes the controller
to output a NEG. 36V signal from J2 pin #1 (wire Vio/Blk) that energizes the K3 brush motor solenoid coil pulling in the high current contactor making
the brush motor(s) turn on (run).
• Scrub Brush Actuator Lift Motor Function
The control board outputs activate (raise and lower) the scrub-deck for installing, removing and controlling the scrub brushes' selected current load.
The negative (-) drive motor wire is specially designed so that it has a known (specified) resistance value. As brush motor current passes through
the negative wire that is, in effect, a low value resistor, a small voltage is developed across it which is proportional to the motor current. Any
temperature change in this wire affects its resistance so the temperature is sensed by a thermistor (*) attached to the wire. 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 M1 actuator motor to raise or lower the scrub deck. This process is on going in maintaining the operator's selected scrub
motor current load (PA #) to sustain the desired brush working pressure.
• Low Voltage Cut-Out Function
The purpose of the low voltage cutout function is to help prolong battery life. The main control board A3 is programmed to monitor the machine's
battery pack voltage to prevent over discharging of the batteries. The brush motors, brush lift actuator and solution solenoid valve will turn OFF
automatically and cease to function when the batteries are discharged to the selected cutout level. The cutout level is adjustable between two
settings. The standard battery type (wet cell) is 31.5 volts (1.75 volts per cell) and maintenance free battery (gel) is 33 volts (1.83 volts per cell).
Note: See the battery section for instruction in selecting (setting) the two different thresholds.
* Thermistor: A special semiconductor resistor whose resistance value varies with temperature.
Note: See the "Know Your Machine" section in this manual for a complete explanation for all scrub system operational modes.
18 - FORM NO. 56043058 Hydro-Retriever™ 3800 / 2042 / BR 1100 revised 7/02