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Table lift mechanism

  • US 4,981,085 A
  • Filed: 08/07/1989
  • Issued: 01/01/1991
  • Est. Priority Date: 08/07/1989
  • Status: Expired due to Fees
First Claim
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1. A piece of furniture comprising in combination:

  • a top portion;

    a pair of lengthwise adjustable leg supports for supporting said top portion for a range of vertical movement, each of said leg supports includes a stationary part and a movable part; and

    a counterbalance mechanism for counterbalancing at least part of the weight of said top portion during vertical movement thereof, said mechanism including drive means for effecting lengthwise adjustment of said leg supports, a counterbalance spring for exerting a variable spring force and coupling means for coupling said spring to said drive means for establishing an essentially uniform counterbalance force on said top portion during vertical movement thereof, said coupling means includes a lever supported adjacent one end thereof relative to said stationary part for pivotal movement about an axis between first and second positions corresponding to lowered and raised positions of said top portion, said spring exerting a bias on said lever tending to pivot said lever from said first position into said second position, and a flexible drive for coupling an opposite end of said lever to said drive means, said drive means includes a pair of racks carried one by each of said movable parts and a pair of driven gears carried one by each of said stationary parts and engaged with said racks, said flexible drive includes sprockets drivingly coupled to said driven gears, a drive chain trained about said sprockets, and a coupling link having opposite ends pivotally connected to said opposite end of said lever and to said drive chain, and said opposite end of said lever moves relatively towards and away from said drive chain incident to movement of said lever from said first position towards said second position.

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