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Boom limit safety control circuit

  • US RE32,366 E
  • Filed: 05/04/1984
  • Issued: 03/03/1987
  • Est. Priority Date: 06/30/1980
  • Status: Expired due to Fees
First Claim
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1. An extensible boom safety control circuit comprising:

  • a. means for generating a coded boom angle word representing the boom angle of elevation comprising a voltage divider network including a pendulum potentiometer having a plurality of sequential swept contacts for providing discrete voltage levels representing boom angles; and

    electrical contact means for contacting said swept contacts of said pendulum potentiometer;

    an electrical bus connected to said electrical contact means;

    a plurality of voltage comparators connected in parallel to said electrical bus for producing a parallel, coded word representing boom angle; and

    a plurality of voltage dividers for providing reference potentials for said plurality of comparators;

    b. means for generating a coded boom length word representing boom length, comprising a plurality of microswitches connected in parallel and means responsive to boom length for actuating said microswitches in a mutually exclusive fashion;

    c. boom angle logic means responsive to said boom angle word and said boom length word for generating a boom extension control signal, wherein said boom angle logic means comprises a plurality of 3-input NAND gates each of which includes a first input electrically connected to one of said comparators, a second input electrically connected via an inverter to a different one of said comparators, and a third input electrically connected to one of said microswitches, and an inhibit function NAND gate including an input for each of said 3-input NAND gates, said 3-input NAND gates each connected to one of said inputs; and

    d. boom length logic means responsive to said boom length word and said boom angle word for generating a boom lowering control signal;

    e. boom extension inhibit means responsive to said boom extension control signal for preventing boom extension; and

    f. boom down inhibit means responsive to said boom lowering control signal for preventing boom lowering.

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