Wheel System, Traction184Service Manual
SC6500|Circuit DescriptionThe wheel drive controller takes in DC power at the battery positive and negative lugs and converts it toan AC output to rotate the wheel drive motor. The drive pedal potentiometer is the primary input to thecontroller, but it also looks at the wheel drive motor temperature and encoder signals. In addition to drivingthe motor, the wheel drive controller also provides outputs to communicate with the “main” (A2) ControlBoard.Wheel Drive Controller Power-upThe battery negative connection is “hard-wired”. The battery positive connection is switched on by the MainContactor (K7). The initial power up sequence begins when key on positive voltage is received at X6-1. This“wakes up” the controller. If there is a positive voltage on the “interlock” circuit X6-9, from the seat switchand the battery interlock switch, the controller turns on the main relay by providing a path to batterynegative on X6-6 for the main contactor winding. The main contactor switches on a high current capacitybattery positive feed to the B+ lug on the wheel drive controller.The controller must receive a positive voltage on the “interlock” circuit X6-9 before it will engage the motor.The interlock circuit is supplied through the seat switch and the battery interlock switch. If either of these isopen, it will disable the wheel drive motor for safety purposes.Note: The battery interlock switch is only used when the machine is equipped with a single large“mono-block” battery. However, the interlock switch connector will be bridged by a“jumper” if the switch is not used on the machine.Motion and Direction CircuitsThe wheel drive controller informs the “main” (A2) Control Board when the vehicle is moving. This MOTIONcircuit uses a dedicated wire that runs between the two controllers to communicate this information.The main controller provides a positive voltage, through a resistor to a switch inside the wheel drivecontroller. The other side of the switch is connected to battery negative. When the vehicle is stationary, theswitch is open and the input voltage is “high”. When the vehicle is in MOTION, the switch closes, whichdrains the voltage supply to battery negative, causing the input to drop to “low”.The wheel drive controller also tells the “main” controller which direction the vehicle is moving. There is(A2) “Main” Control BoardInput+ VWheel Drive ControllerB-
