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Snag load protection system for a crane

  • US 5,597,080 A
  • Filed: 08/02/1994
  • Issued: 01/28/1997
  • Est. Priority Date: 08/02/1994
  • Status: Expired due to Term
First Claim
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1. A snag load protection system for a crane comprising:

  • a guide frame;

    a sheave housing slidably received within said guide frame, said sheave housing having means therein for receiving a rotatable sheave; and

    a hydraulic cylinder means connected to said guide frame and to said sheave housing, said hydraulic cylinder means for exerting a compressive force against said sheave housing so as to resist relative movement between said guide frame and said sheave housing when forces exerted by said sheave housing are within a predetermined value, said hydraulic cylinder means comprising;

    a piston rod having one end connected to said sheave housing;

    a cylinder receiving an opposite end of said piston rod, said cylinder affixed to said guide frame;

    hydraulic supply means connected to said cylinder for supplying fluid to said cylinder at a desired pressure, said hydraulic supply means comprising;

    a fluid reservoir;

    a fluid line extending from said fluid reservoir to said cylinder; and

    pressurizing means connected to said fluid line for pressurizing the fluid in said cylinder, said pressurizing means comprising;

    a pump connected to said fluid line; and

    a pressure switch means connected to said fluid line and to said pump, said pressure switch means for actuating said pump when the pressure of the fluid in the line falls below a predetermined value;

    a relief valve means connected to said hydraulic supply means, said relief valve means for releasing said hydraulic fluid from said cylinder when the forces exceed the predetermined value; and

    a pressure sensor means connected to said hydraulic cylinder means, said pressure sensor means for transmitting a signal when the forces exceed the predetermined value.

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