Nilfisk-Advance CMAX 28/34ST Service Manual

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Nilfisk-Advance CMAX 28/34ST Service Manual Manual pdf 43 page image

42 - FORM NO. 56043071 CMAX™ 28/34ST / I-MAX ™ 28/32C, BA 750/850ST, BA 750CWHEEL DRIVE SYSTEMREDFUSE, 150AF11 2 RED BT1+ -BATTERY24VDC OR 36VDCBLKBLKA1CONTROL BOARDRED GRNF21 2CIRCUIT BREAKER5 AMPS3SWITCHSPST KEYGRNGRA/BLK413B-2B-314 B+21 B+1BRN 567 1112FOR/REVB-1298310BLKRED F31 2CIRCUIT BREAKER30 AMPWHT/YELBRNYELYELR1POT. 5K OHM THROTTLEA21208 SPEED CONTROLLERM1MMOTOR, WHEEL DRIVE+-BRN/BLKYEL/REDB-(T2)B+(T1)B+B-P2(T3)M1(T4)M2+ WHENFORWARDP112123456OUTPUTOUTPUTKEYSWITCHREVERSEWIPERFORWARD+-VIOBRN/WHT GRN/YEL132POT. 25K OHM SPEED LIMIT1223 1RED/BLKGRA R2GENERAL FUNCTIONAL OVERVIEWSee Figures 1 and 3. A 1/2 horsepower permanent magnet (24V or 36V) motor (M1) is used for the wheel drive on all machines. The motor outputis delivered to a single front mounted drive wheel driven by a chain as shown in Figure 3. A Curtis PMC solid state speed controller (A2) regulatesthe variable speed and Fwd/Rev wheel drive motor functions. Location of the controller is in the rear handle housing electrical compartment(accessible by removing the 4 screws securing the large rear electrical panel). The potentiometer R1 mounted in the drive paddle inputs to theA2 controller the machine operator’s throttle (variable speed) and direction demands. A second pot R2 (knob adjusted) is mounted on the topsurface of the handle housing and controls the machine’s maximum transport and scrub speeds.Drive Motor System FunctionSee Figures 1 and 2. With the key switch S3 closed the Brn wire inputs 24V or 36V to the A2 speed controller (terminal #3) to make its internalcontrol circuits operational (powering it up). The F3 circuit breaker (30 Amp) supplies the positive load circuit voltage input to the B+ controllerterminal (Wht/Yel wire). The black wire from the battery negative standoff supplies the (NEG.) input to the B- controller terminal.Moving the 5K Ohm R1 pot off its centered balanced neutral setting of approximately 2500 Ohms, activates the operator input to the speed control.Forward or reverse movement of the drive paddle rotates the pot shaft and the pot’s variable resistance value changes which generates the internalvoltage signals (0-5Volts) needed for the controller’s output operation. These control board voltage input signals are what energizes the Fwd andRev directional relays, which then selects the motor polarity and final voltage level outputs at the M1 & M2 terminals.When the operator turns the R2 speed limit Pot from min. to max. (CW) this causes an input resistance relationship change between the pot high(+) and wiper terminals (high to low Ohms) thus increasing the maximum wheel motor operating speed range. Turning the knob (CCW) increasesthe resistance and the motor speed range is reduced.FIGURE 1Electrical Diagram*For complete description of all callouts see Electrical System Wiring Diagram.revised 11/02