Abstract: A computer control technique controls a chemical spreading operation such as the spreading of a salt-sand composition from a truck hopper. The vehicle has a spinner motor controlled by the vehicle operator from the control panel which is preferably disposed in the vehicle cab, and a conveyor motor operated under computer control and operator control. A display is part of the control panel and indicates conveyor motor speed to the operator. The operating power for the system, and in particular the conveyor motor, is derived from an AC generator (alternator) preferably driven from the fan belt drive of the vehicle motor thus not requiring any separate motor drive or hydraulic drive. In one embodiment a single alternator is used for both conveyor motor power and normal electrical vehicle power, while in an alternative embodiment separate alternators are employed both associated with the vehicle motor.