Patent ID: 8290667

Claim:
A method of operating a drive motor driving both a tractor, via a tractor drive, and a trailer, via a traveling power takeoff shaft, the traveling power takeoff shaft having at least three discrete, shiftable power takeoff gear stages and the traveling power takeoff shaft being connected to the drive motor, the method comprising the steps of: defining higher and lower motor rotational speed threshold values and providing the higher and the lower motor rotational speed threshold values to an electronic system for controlling the drive motor and the power takeoff gear stages; determining by a speed sensor one of a wheel speed and a vehicle speed; and operating the electronic control responsive to the one of the wheel speed and the vehicle speed, controllingly conforming a rotational speed of the traveling power takeoff shaft to a ratio of at least one of the determined vehicle speed and the determined wheel speed by adjusting slip operation of the traveling power takeoff shaft and rotation of the motor so that the tractor and the trailer travel at substantially a same speed; comparing the determined one of the wheel speed and the vehicle speed to the higher and the lower motor rotational speed threshold values; and shifting a power takeoff stage to one of a corresponding next higher and a next lower discrete shiftable power takeoff stage, upon attainment of one of the higher and the lower motor rotational speed threshold value, so as to maintain an optimal traveling speed for both the tractor and the trailer so that both the tractor and the trailer travel together substantially as an integrated unit at substantially the same speed.