Safety system for cranes

• US 3,969,714 A
• Filed: 01/06/1975
• Issued: 07/13/1976
• Est. Priority Date: 01/06/1975
• Status: Expired due to Term

• Current Assignee: Standex International Corporation
• Original Assignee: Gerald L. Greer
• Inventors: Greer, Gerald L.
• Primary Examiner(s): Trafton, David L.
• Application Number:
  US05/538,554
• Time in Patent Office: 554 Days
• Field of Search: 340/224, 340/267 C, 212/39 R, 212/39 MS
• US Class Current: 340/679
• CPC Class Codes: B66C 13/50 Applications of limit circuits or of limit-switch arrangements for winding mechanisms B66D1/56
• CPC Class Codes: B66C 15/06 Arrangements or use of warning devices

Abstract

A safety system for sensing the position of a load being carried by a crane, relative to the boom thereof. It comprises a self-powered radio transmitter positioned on the end of the boom of the crane, and an on-off switch to be engaged by a load-carrying block or hook whenever the load is in close proximity to the boom.

The system further comprises a radio receiver within the cab of the crane, such receiver being connected in circuit with suitable warning devices to energize the same upon receipt of a radio signal from the transmitter.

Claims

1. A safety system for cranes having a boom, a load-carrying device thereon movable with respect to said boom to raise and lower a load as desired and an operator'"'"'s cab, comprising in combination,

a radio signal transmitter mounted at one end of said boom and having its own portable source of electric power thereat,

an on-off control switch connected in circuit with said transmitter and said source of power having at least one pair of cooperating electrical contacts and biasing means associated therewith biasing said contacts to open circuit relation to effect energization of said transmitter by said source when moved to closed circuit relation against said biasing means, said switch being suspended a predetermined distance below said one end of said boom to be operated by upward movement of said load-carrying means before it contacts said one end of said boom,

and warning means including a radio signal receiver connected in circuit with the electrical energy source in the operator'"'"'s cab of said crane normally used to power said crane and a warning device in said cab and in circuit with said receiver to be energized when, but only when, said receiver is receiving a signal from said transmitter.

2. A safety system for cranes having a boom, a load-carrying device thereon movable with respect to said boom to raise and lower a load as desired and an operator'"'"'s cab according to claim 1,

wherein said control switch is suspended from said one end of said boom over said load-carrying device.

3. A safety system for cranes having a boom, a load-carrying device thereon movable with respect to said boom to raise and lower a load as desired and an operator'"'"'s cab according to claim 2,

wherein a transmitting antenna is provided at said transmitter and a receiving antenna is provided at said receiver to send and receive respectively, said radio signal when but only when said switch contacts are in closed circuit position.