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Four-wheel drive assist for electric machines

  • US 6,892,846 B2
  • Filed: 04/30/2001
  • Issued: 05/17/2005
  • Est. Priority Date: 05/02/2000
  • Status: Expired due to Term
First Claim
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1. An electric motor driven lift machine comprising:

  • a vehicle chassis supporting four wheels and at least one hydraulically driven operating arm;

    at least one electric motor coupled with a first set of the plurality of wheels for driving the first set of the plurality of wheels;

    at least one hydraulic motor coupled with a second set of the plurality of wheels for selectively driving the second set of the plurality of wheels, wherein the first set and the second set of the plurality of wheels each comprises two of the four wheels, the electric motor driven lift machine including two hydraulic motors respectively coupled with each of the second set of the plurality of wheels;

    a hydraulic pump driven by a pump motor and coupled with a source of hydraulic fluid, the hydraulic pump being in fluid communication with the at least one hydraulic motor and the at least one hydraulically driven operating arm, wherein the pump motor is separate from the at least one electric motor;

    a flow divider in fluid communication with the hydraulic pump, the flow divider dividing hydraulic fluid flow between each of the second set wheels of the plurality of wheels; and

    a traction sensor that detects whether one of the wheels in the second set of the plurality of wheels loses traction, the traction sensor communicating with the flow divider, wherein the flow divider applies a higher pressure to the other of the second set wheels of the plurality of wheels according to a signal from the traction sensor.

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