Proximity differential control

Claim 2

A proximity differential control for use with construction equipment having movable equipment associated therewith operating in the near proximity of high voltage power lines, said differential control comprising a reference antenna which is positioned below said lines at the closest desired horizontal distance of the movable equipment from said lines, a sensing antenna substantially identical to said reference antenna and positioned on the movable equipment, receiving and amplifying means operably connected to the reference antenna, a separate and substantially identical receiving and amplifying means operably connected to said sensing antenna, and control means for comparing the relative strength of the electrical field surrounding the reference antenna and the field surrounding the sensing antenna and for electrically shutting down the movable equipment when said sensing antenna moves into an area having a greater electrical field strength than that of said reference antenna.

Claim 3

A proximity differential control for use with construction equipment operating in the near proximity of high voltage power lines as set forth in claim 1 wherein means are provided to raise and lower the reference antenna.

Claim 4

A proximity differential control for use with construction equipment operating in the near proximity of high voltage power lines as set forth in claim 2 wherein the means for raising and lowering the reference antenna comprises an elongated antenna mount hingedly secured to the construction equipment along the mid portion thereof, one end of the said antenna mount being secured to the reference antenna and the opposite end thereof being operably connected to the movable equipment whereby the said reference antenna is automatically raised when the movable equipment is raised and automatically lowered when the movable equipment is lowered by rotation of the elongated antenna mount.

Claim 5

A proximity differential control for use with construction equipment operating in the near proximity of high voltage power lines as set forth in claim 1 wherein a single automatic gain control unit is provided having its input operably connected to the output of the reference receiving and amplifying means, and having its output operably connected to both of the receiving and amplifying means for the sensing antenna and reference antenna for balancing and controlling the gain of each of said amplifying means.

Claim 6

A proximity differential control for use with cranes having booms operating in the proximity of high voltage power lines, said proximity differential control comprising a reference antenna which is positioned below said lines at the closest desired horizontal distance of said boom from said lines, a sensing antenna substantially identical to said reference antenna and positioned on the movable equipment, receiving and amplifying means operably connected to said reference antenna, separate and substantially identical receiving and amplifying means operabLy connected to said sensing antenna, and control means for comparing the relative strength of the electrical field surrounding said reference antenna and the field surrounding said sensing antenna for electrically shutting down the movable equipment when said sensing antenna moves into an area having a greater electrical field strength than that of said reference antenna, and wherein said control means comprises a coil operated self-latching relay for controlling power to the crane, a multiple coil differential control relay having a set of contacts operably connected to the coil of the self-latching relay and having a first coil operably connected to the output of the receiving and amplifying means for the reference antenna which tends to keep the contacts of the differential control closed, the differential control relay also having a separate opposing coil operably connected to the receiving and amplifying means for the sensing antenna so that when the output from the receiving and amplifying means for the sensing antenna becomes greater than the output from the receiving and amplifying means for the reference antenna, the contacts for the first differential control relay will open thereby de-energizing the first-mentioned relay which, in turn, removes power from the crane boom.

Claim 7

A proximity differential control for use with cranes having booms operating in the proximity of high voltage power lines, said proximity differential control comprising a reference antenna which is positioned below said lines at the closest desired horizontal distance of said boom from said lines, a sensing antenna substantially identical to said reference antenna and positioned on the movable equipment, receiving and amplifying means operably connected to said reference antenna, separate and substantially identical receiving and amplifying means operabLy connected to said sensing antenna, and control means for comparing the relative strength of the electrical field surrounding said reference antenna and the field surrounding said sensing antenna for electrically shutting down the movable equipment when said sensing antenna moves into an area having a greater electrical field strength than that of said reference antenna, and wherein said control means comprises a coil operated self-latching relay for controlling power to the crane, a multiple coil differential control relay having a set of contacts operably connected to the coil of the self-latching relay and having a first coil operably connected to the output of the receiving and amplifying means for the reference antenna which tends to keep the contacts of the differential control closed, the differential control relay also having a separate opposing coil operably connected to the receiving and amplifying means for the sensing antenna so that when the output from the receiving and amplifying means for the sensing antenna becomes greater than the output from the receiving and amplifying means for the reference antenna, the contacts for the first differential control relay will open thereby de-energizing the first-mentioned relay which, in turn, removes power from the crane boom.

Claim 8

A proximity differential control for use with construction equipment operating in the near proximity of high voltage power lines as set forth in claim 5 wherein the proximity differential control also comprises sensing antenna continuity testing means, said testing means comprising a coil actuated test relay operably connected to the sensing antenna and switching means connected to the test relay for actuating said test relay said test relay being connected such that power is supplied to the control system of the crane only if the sensing antenna exhibits continuity when the test relay is actuated.

Claim 9

A proximity differential control system for use with movable cranes having pedestal mounted boom structures operating in the proximity of high voltage electrical power lines, said differential control system comprising a reference antenna which is positioned above the boom pedestal, said pedestal being positioned at the closest desired horizontal distance from said lines, a sensing antenna substantially identical to said reference antenna and positioned on the boom structure of the crane, receiving and amplifying means operably connected to the reference antenna, separate and substantially identical receiving and amplifying means for said sensing antenna, and control means for comparing the relative electrical field strength surrounding the reference antenna and the field surrounding the sensing antenna for electrically shutting down the boom operation when said sensing antenna moves into an area having a greater electrical field strength than that of the reference antenna.

Claim 10

A proximity differential control system for use with movable cranes having pedestal mounted boom structures operating in the proximity of high voltage electrical power lines, said differential control system comprising a reference antenna which is positioned above the boom pedestal, said pedestal being positioned at the closest desired horizontal distance from said lines, a sensing antenna substantially identical to said reference antenna and positioned on the boom structure of the crane, receiving and amplifying means operably connected to the reference antenna, separate and substantially identical receiving and amplifying means for said sensing antenna, and control means for comparing the relative electrical field strength surrounding the reference antenna and the field surrounding the sensing antenna for electrically shutting down the boom operation when said sensing antenna moves into an area having a greater electrical field strength than that of the reference antenna.

Claim 11

A proximity differential control system for use with movable cranes having a pedestal mounted boom operating in the near proximity to high voltage electrical power lines, the said differential control system comprising a reference antenna which is movably positioned above the horizontal boom pedestal, the said reference antenna being positioned at substantially the closest desired horizontal distance from the high voltage power line, a first sensing antenna located on the top of the outer end of the boom and a second substantially identical sensing antenna secured substantially mid-way out on the bottom of the boom so that when one of the sensing antennas is hidden from the electrical power line by the boom structure the other will be exposed thereto, receiving and amplifying means operably connected to the reference antenna, substantially identical receiving and amplifying means operably connected to the sensing antennas and control means for comparing the relative electrical field strength surrounding the sensing antennas to that of the reference antenna.

Claim 12

A proximity differential control system for use with movable cranes having a pedestal mounted boom operating in the near proximity to high voltage electrical power lines, the said differential control system comprising a reference antenna which is movably positioned above the horizontal boom pedestal, the said reference antenna being positioned at substantially the closest desired horizontal distance from the high voltage power line, a first sensing antenna located on the top of the outer end of the boom and a second substantially identical sensing antenna secured substantially mid-way out on the bottom of the boom so that when one of the sensing antennas is hidden from the electrical power line by the boom structure the other will be exposed thereto, receiving and amplifying means operably connected to the reference antenna, substantially identical receiving and amplifying means operably connected to the sensing antennas and control means for comparing the relative electrical field strength surrounding the sensing antennas to that of the reference antenna.