Nilfisk SC750 User Manual

Loading ...

Service Manual: SC750, SC800, SC 750 ST, SC800 ST

Form Number 56043150 Page 86

Scrub System – Cylindrical

Functional Description

The scrub system moves the scrub head up and down and turns the scrub motors on and o at the operator’s request, to

provide oor scrubbing acon. The brushes spin toward one another at the boom. The head is moved up and down by

an electric actuator motor that has integrated posion switches. The weight of the scrub head provides the downward

pressure for scrubbing. The actuator linkage is sloed to allow the brush head to “oat” when going over low and high

spots on the oor. A spring is used to li just a bit of weight in order to obtain opmal scrub pressure weight. Note: The

cylindrical scrub system does not have an “extreme pressure” mode.

• The Main Machine Controller energizes the brush solenoid to turn on the brush motors when the following

inputs have been met:

o Key switch on

o Operator request

o Machine moving signal (FOR/REV)is received from the Drive Motor Controller (A2 PG Drives Speed Con-

troller)

 Approximately 24 volts received from the main controller (J3 Pin 6) is switched to baery nega-

ve by the Drive Motor Controller, dropping the voltage to 0 volts.

Here is how the circuit works for the scrub motors: The Main Machine Controller turns on the scrub motors indirectly

by energizing the Brush Contactor. The brush contactor coil is fed baery posive voltage through the key switch. The

voltage goes through the coil and on to the controller. Inside the controller, it switches the circuit to baery negave to

energize the relay. When the relay energizes, posive baery voltage is applied through its contacts to the brush motors.

Since the other side of the motors is connected to baery negave, they turn on.

The Main Machine Controller also monitors the amount of electrical current (Amps) that is owing through the brush

motor ground circuit. If it is higher or lower than expected a fault code will be set. It monitors the amperage indirectly

on a “sense” wire by measuring the dierence in voltage (Voltage Drop) between a point near the motors and the main

baery negave terminal. As actual current increases, the voltage drop measured increases. The controller then converts

the voltage value to “Amps”. The monitoring circuit relies on a calibrated ground wire that is a specic gauge and length.

An electric actuator is used to move the scrub head up and down. The actuator has a DC permanent magnet electric mo-

tor which is driven by the Main Machine Controller. The motor turns a threaded sha. When the threaded sha turns, it

moves a threaded rod up and down. Since the rod is aached to the deck, it moves the deck up and down.

Inside the actuator housing, there are also three posion switches which are monitored by the Main Machine Controller.

One for the “retracted” posion, one for the “middle” posion (Normal scrub pressure) and one for the “Extended” posi-

on (Extreme scrub pressure). Each switch is normally closed. The threaded rod has a collar on it that opens each switch

as it passes by it. When the Main Machine Controller sees the middle posion switch open, it knows that the deck is in

the normal scrub posion. If that was its goal posion, the controller turns o the motor to stop the deck in that posi-

on.

Loading ...

Nilfisk SC750 Heavy-Duty Cleaning