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Lift axle control system

  • US 4,854,409 A
  • Filed: 11/19/1987
  • Issued: 08/08/1989
  • Est. Priority Date: 11/19/1987
  • Status: Expired due to Term
First Claim
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1. In a control system for a lift axle in a two-axle suspension for wheeled vehicles wherein:

  • first and second axles are connected in tandem to a vehicle frame through first and second suspensions, respectively;

    said second suspension having means to mount said second axle for movement between a raised position and a lowered position, and actuation means for moving said second axle between said raised and lowered positions;

    said second axle having wheels for supporting engagement with the ground when the second axle is in the lowered position and said wheels being out of contact with the ground when said second axle is in a raised position;

    control means having a means to detect a load on the first axle and for automatically raising said second axle to said raised position when the load on the first axle is below a first predetermined value, and a means for automatically lowering said second axle to said lower position when the load on said first axle is above a second predetermined value which is greater than the first predetermined value, and means to delay the operation of said actuation means to lower said second axle upon detection of a load on said first axle to compensate for road bumps;

    the improvement which comprises;

    said load-detecting means comprising electrical sensing means and said control means comprising electrical circuit means to control said activation means responsive to a signal from said electrical sensing means.

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