Gm Global Technolgoy Operations, Inc.

Clifford H Oehme

Charles Francis Long

James A Redelman

James P Ordo

The present invention provides a traction control method for a tracked vehicle such as a military tank. The method includes calculating a track proportionality factor and a vehicle proportionality factor based on predefined attributes of the tracked vehicle. A minimum turn radius of the tracked vehicle is calculated based on the velocity of the tracked vehicle, the maximum coefficient of friction between the tracks of the tracked vehicle and the ground (0.7), and gravitational acceleration (9.80665 m/s2). A sprocket rotational speed is calculated based on the pitch diameter of the tracked vehicle sprockets and the velocity of the tracked vehicle. Based on the preceding calculations, the method of the present invention calculates a required track speed differential configured to turn the tracked vehicle at the minimum turn radius. If a commanded turn radius is less than the minimum turn radius, the track speed differential of the tracked vehicle is limited to the required track speed differential to prevent the tracked vehicle from slipping.

Traction control method for a tracked vehicle

The present invention provides a method and apparatus for brake steering a tracked vehicle such as, for example, a military tank. More precisely, the present invention provides independent control of a left brake and a right brake to create a track speed differential and thereby turn the vehicle. The apparatus of the present invention preferably includes a controller, a plurality of circuit selector actuators operatively connected to the controller, and a plurality of brake apply actuators operatively connected to the controller. A plurality of valves are disposed in fluid communication with the plurality of circuit selector actuators. The left brake is in fluid communication with one of the plurality of brake apply actuators, and the right brake is in fluid communication with another of the plurality of brake apply actuators. The controller is configured to control the plurality of brake apply actuators to independently apply the left brake and the right brake such that the tracked vehicle can be turned in a desired manner.

Brake steering method and apparatus

A hydraulic system for an electro-mechanical transmission includes an electrically-powered main pump, a battery powered auxiliary pump and an output pump. The main pump provides fluid to transmission components such as a torque-transmitting mechanism. The auxiliary pump provides fluid pressure to engage the torque-transmitting mechanism when electric power to the main pump is unavailable or the main pump is otherwise inoperable. The engaged torque-transmitting mechanism enables rotation of an output member which mechanically powers the output pump so that it may provide fluid to the transmission components in lieu of the main pump. A method of providing fluid to transmission components is also provided.

Hydraulic system for an electro-mechanical transmission and method of providing fluid to transmission components

An electro-hydraulic control system for a transmission is provided having first, second, and third selectively engageable torque transmitting mechanisms. The control system includes a main source of fluid pressure and first, second, and third trim valves operable to effect the engagement of respective first, second, and third torque transmitting mechanisms. A latch valve is in fluid communication with the first torque transmitting mechanism and an interlock valve is in selective fluid communication with the latch valve. The first trim valve, latch valve, and interlock valve are in fluid communication with the main source of fluid pressure. The first trim valve operates selectively communicate fluid pressure to the latch valve to effect engagement of the first torque transmitting mechanism, while the interlock valve is operable to selectively communicate fluid pressure to one of the second and third trim valve to effect engagement of the respective second and third torque transmitting mechanisms.

Electro-hydraulic control system with interlock protection

A power transmission has a plurality of shift valves each of which has an engaged position and a disengaged position. Each shift valve has a pair of chambers which is selectively pressurized by a latching valve to maintain the shift valves in their respective selected positions. During a ratio change, the latching valve discontinues pressure at the respective shift valve chambers to permit the appropriate shift valve movement.

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Avon, IN, United States of America

Clifford H Oehme