The United States of America As Represented by the Administrator of the

Ronald M Schaefer

Charles L Gray, Jr

Karl H Hellman

A vehicular powertrain with regenerative braking includes a plurality of wheels and a brake pedal which, upon engagement, is activated first into a first zone of operation and then into a second zone of operation. A braking detector detects either a released state or an engaged state for the brake pedal and, if in the engaged state, detects if the pedal is in the first or the second zone of operation. Friction brakes brake a pair of the wheels, responsive to detection of the brake pedal within the second zone of operation. The hydraulic portion of the drivetrain includes an accumulator for storing hydraulic fluid under pressure and a reservoir for storing the hydraulic fluid at a lower pressure. A pump/motor is located in the high pressure line for operation as a motor to drive the drive wheels in a drive mode and for operation as a pump driven by the drive wheels in a braking mode. A prime mover has its inlet connected to the reservoir through a low pressure line and an outlet connected to the accumulator through a high pressure line and hydraulically drives said pump/motor in its motor mode. A controller switches the pump/motor into the braking mode responsive to detection of an engaged state for the brake pedal and into the drive mode responsive to detection of the released state of the brake pedal. A switch valve connects the high pressure line to the accumulator in the braking mode and to the reservoir in the drive mode.

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Novi, MI, United States of America

Ronald M Schaefer