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Front wheel drive engagement control system for agricultural vehicles

  • US 5,802,489 A
  • Filed: 11/14/1994
  • Issued: 09/01/1998
  • Est. Priority Date: 11/14/1994
  • Status: Expired due to Term
First Claim
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1. In an agricultural vehicle having an engine, a first pair of wheels driven by the engine, a second pair of wheels and an engagement circuit for selectively engaging and disengaging the second pair of wheels to the engine in response to control signals for driving the second pair of wheels, a control system comprising:

  • a vehicle velocity sensor including a radar emitter and a radar receiver configured to detect a parameter indicative of the ground velocity of the vehicle independent of the velocity of the second pair of wheels and to generate a vehicle velocity signal representative thereof;

    a wheel velocity sensor configured to detect the velocity of at least one of the first pair of wheels and to generate a wheel velocity signal representative thereof;

    a comparator circuit coupled to the vehicle velocity sensor and to the wheel velocity sensor and configured to compare the vehicle velocity signal and the wheel velocity signal and to generate a slip signal representative of the degree of slip of at least one of the first pair of wheels; and

    a control circuit coupled to the comparator circuit and to the engagement circuit and configured to generate control signals and to apply the control signals to the engagement circuit, wherein the control signals cause the engagement circuit to engage the engine and thereby drive the second pair of wheels when the degree of slip is above a predetermined value and to disengage the engine and thereby not drive the second pair of wheels when the degree of slip is below the predetermined value.

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