US3087530A - Single pole hot stick - Google Patents

Description

April 30, 1963 w. REISCHER ETAL ,0

SINGLE POLE HOT STICK 7 Filed Jan. 10, 1961 4 Sheets-Sheet 1 INVENTORS WALTER REISCHER WALTER J. FRANK,JR.

BRUCE MALKIN ATE'Q w. REISCHER ETAL 3,087,530

SINGLE POLE HOT STICK Filed Jan. 10, 1961 4 Sheets-Sheet 3 'TTTW NVEVTORS ALTER REISCHER 3y LTER J.FRANK,JR..

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April 30, 1963 w. REISCHER ETAL 3,037,530

SINGLE POLE-HOT STICK Filed Jan. 10, 1961 4 Sheets-Sheet 4 INVENTORS WALTER'REiSCHER By wALTERJJ'RANigJR. sauce: M. LK

United States atent 3,087,530 SINGLE POLE HGT STICK Walter Reischer, South Nor-walk, Walter J. Frank, In,

Darien, and Bruce M. Malkin, Stamford, Conn., assignors to lSurntly Corporation, a corporation of New York Filed Jan. 10, 1961, Ser. No. 81,784 9 Claims. (Cl. 153-1) This invention pertains to devices used to install a compression type connector on an energized electrical conductor.

In the past, when it was necessary to install a compression type connector on an energized conductor with a hydraulically operated indenting machine, a mechanically operated hot stick was attached to the machine to operate it. This hot stick was commonly a pivoted twopole device, which was operated in scissors tashion. This was often quite inconvenient, especially when working at a distance from the ground.

There has recently been developed a semihydraulically operated single pole hot stick, This stick includes a long hollow plastic tube having a long plastic rod disposed therein. A hydraulic power pump supplies pressure to a hydraulic circuit which is connected to one end of the hollow tube. The rod transmits a force, which must be kept rather low to prevent destruction of the rod, to a hydraulic pressure converter at its other end. The converter develops the full pressure necessary to operate the ram of the indenting machine. Since the rod is rather narrow, having a small end area, and the force the rod transmits is kept low, a hydraulic converter to increase the pressure is required. The converter is based on Pascals principle: that a small force exerted on a small area through a long distance in a closed hydraulic circuit will exert a large force on a large area through a small distance. The converter then applies the required force on the ram of the indenting machine.

The disadvantages of this scheme are that the extra length and weight of the hydraulic converter are placed at the end of the tube, making the tube quite unwieldly and tending to flex the tube excessively. If the converter is not covered with insulation, its conductive length becomes hazardous when working with a plurality of closely-spaced energized conductors. Further, since there must be some clearance between the rod and tube, condensation may occur therebetween, which may contaminate the hydraulic media. Also undiscovered contamination or loss may occur between the hydraulic media.

An object of this invention is to provide a light weight single pole hot stick which has a low moment of inertia and may be conveniently handled and operated.

Another object of this invention is to provide a hot stick having a minimum conductive portion adjacent the indenting machine.

Yet another object of this invention is to provide a hot stick whose rigid pole is completely hydraulic.

, A further object of this invention is to provide a hot stick wherein contamination of the hydraulic media is prevented.

A yet further object of this invention is to provide a hot stick which will retain a connector in its indenting machine without indenting it, and at the operators convenience will indent the connector.

A feature of this invention is a hydraulically operated indenting machine which, with the exception of a hydraulic media separator, utilizes hydraulic means for intermediate force transmission throughout the system.

Another feature of this invention is the use of a low pressure overload valve in shunt with the main force transmission system whereby the force applied by the 3,087,530 Patented Apr. 30, 1963 2 indenting machine may be kept below indenting pressure at the operators convenience.

These and other features and objects of this invention will become more apparent by reference to the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a front view of a hydraulically operated hot stick embodying this invention;

FIG. 2 is a longitudinal sectional view of the hollow extension tube and hydraulic media separator of this invention;

FIG. 3 is a longitudinal sectional view of a modification of the tube illustrated in FIG. 2;

FIG. 4 is a front view in partial section of the hydraulic switching system of this invention; and

FIG. 5 is a schematic of the electrical switching system of this invention.

A complete system embodying this invention is illustrated in FIG. 1. A hydraulically operated indenting head 101 containing dies 103 and 105 is connected to a hydraulic power pump 401 by means of a flexible tube 107, a hydraulic media separator housing 201 and a rigid eX- tension tube 203. The pump 401 has associated therewith an electrical power supply (not shown) and an electrical control box 501 including an air bulb 109 and insulated tube 111 for remotely actuating the control box 501.

FIG. 2 illustrates the extension tube 203 and the hydraulic media separator 201. Separator 201 includes an upper housing 205 and a lower housing 207 threaded thereto to provide a central cylinder 209. Lower housing 207 is bored at 211 and threaded at 213 to receive flexible tube 107 and to pass hydraulic media into the cylinder 209. A separator disk 215 is free to move along the axis of, and with the cylinder 209. The separator includes a spring return arrangement of a central rod 217 pinned at 219 to the housing 207 and a compression spring 221 held between two end plates 223 and 225. Upper end plate 225 is prevented from loosing rod 217 by a 0 spring 227 while lower end plate 223 is prevented from escaping the separator by C spring 229. The separator has an upper annular ring seal 231 and a lower annular ring seal 233, and thus separates cylinder 209 into a hydraulically isolated upper half 209a and a lower half 2091). An escape port 235 is provided through upper housing 205 to indicate the presence of, and to drain, any hydraulic media which might pass the ring seals to the central periphery 237 of the separator 215.

The upper housing is bored at 239 to pass hydraulic media to the rigid extension tube 203, which may be made of hollow fiberglass capable of withstanding 10,000 psi. The housing and tube may be secured toget-her by suitable means such as cementing. The other end of tube 203 may be cemented to a cap 241 which is bored and threaded as at 243 and 245 to be secured to, and to pass hydraulic media to the indenting head 101.

The lower hydraulic system which includes cylinder portion 20% must of necessity contain hydraulic oil, because the hydraulic pump is designed to operate on same. Hydraulic oil, however, does not possess the best available dielectric properties. Furthermore, the oil, over a period of use in the pump, has a tendency to pick up contaminants. Therefore, a transformer oil is used for its dielectric properties in the upper hydraulic system which includes cylinder portion 209a and which comes into proximity, via the indenting head 101, with the energized conductors. The separator 215 is provided to isolate the upper and lower hydraulic systems and prevent contamination therebetween. It will be noted that complete electrical isolation between the indenting head and the media separator housing over the full length of the extension tube is thus obtained. Furthermore, no additional hardware is necessary between the extension tube and the indenting head, which would add to the electrically conducive length or the weight of the operating end of the hot stick.

FIG. 3 illustrates a modified form of the extension tube. Rigid tube 303 which is part of the upper hydraulic sys tem 301a is surrounded by another rigid tube 304. The space 306 bet-ween the concentric tubes 3G3 and 304 is filled with loose fiberglass.

The use of the second outer tube 304 gives the combination of tubes a greater rigidity, while permitting thinnerwalled tubing to be employed. Should a rupture of the inner tube 303 somehow occur in use, the outer tube 304 will contain the explosion and prevent injury to the operator.

FIG. 4 illustrates the novel hydraulic switching circuit 403, and FIG. 5 illustrates the electrical switching circuit 501 of this invention. The systems may be set for either semiautomatic or manual operation. Considering the semi-automatic operation first: a double pole double throw switch 511 may be set in its automatic position (A), and a connector inserted into the identing head of the hot stick. Squeezing the air bulb 109 closes the normally open switch 513, which completes a circuit via contact 511-aa to the coil 515a of a two gang pulse-to-step stepping switch 515. The stepping switch 515 moves to its first position (I), which completes, via contact 5154a, a circuit to the coil 517a of the normally open pump motor relay 517, which in turn starts the pump motor 519.

The pump 401 pumps oil through the intake 411 into the central chamber 413, and out through the outlet 415 to the hot stick. A spring 417 and a rod 419 hold a spring loaded ball check 421 away from its seat to permit a diversionary flow of oil to a ball check valve 423 having a spring loaded ball check 425 which unseats at about 50 p.s.i. to permit the diversionary flow of oil to flow out of the outlet 427 to return to the oil pump 401. The connector is thus retained in the identing tool at low pressure and without being crimped.

A second squeezing of air bulb 109 again momentarily closes switch 513 to pulse the stepping switch 515 to its second position (II) which continues, via contact 515-2a to close relay 517 to operate the pump motor 519. The contact 515-21) completes a circuit to the oil control solenoid 520 which pulls up the rod 419 and permits the ball check 421 to seat, closing oil the passage to the diversionary outlet 427. The oil pressure in the cavity 413, and the hot stick continues to build up to the desired indenting pressure which may be 5800 p.s.i. At indenting pressure, the spring loaded stem 429 of the pressure cutoff valve 431 is forced open, permitting a diversionary flow of oil through the relief tube 433 and out through the outlet 427. Oil at reduced pressure, about 300 p.s.i., also passes through the outlet 435 to close a normally open switch 521 which completes a circuit, via the contacts 511-ab and 511-all, to the stepping switch 515, which steps to its off position, opening the relay 517 and stopping the pump motor 519. Due to the oil flow out of the tube 433, pressure is maintained for only a short interval in the valve 431 and against the switch 521, preventing any overheating of the stepping switch coil 515a. The stopping of the pump is an audible signal to the operator that a proper crimp at full pressure has been made, and the hot stick may be removed from the connector. The ram also begins to retract when the pump is shut off, therefore indicating completion of the crimp even if the pump shut otf can not be heard.

If switch 11 is placed in its manual position (M), a circuit is completed via the contact 511-ma to the relay 517 which turns on the pump motor 519. A circuit is also completed via the contact 511-mb to the oil control solenoid 520 which pulls up the rod 419 to permit the ball check 421 to seat, permitting indenting oil pressure to build up. Indenting pressure opens the valve 431, by-

passing the hot stick. The operator now turns off the pump motor.

The invention has thus been described but it is desired to be understood that it is not confined to the particular forms and usages shown or described, the same being merely illustrative, and that the invention may be carried out in other ways without departing from the spirit of the invention, and therefore, the right is broadly claimed to employ all equivalent instrumentalities coming within the scope of the appendent claims, and by means of which objects of this invention are attained and new results accomplished, as it is obvious that the particular embodiments herein shown and described are only some of the many that can be employed to obtain these objects and accomplish these results.

We claim:

1. A system for compressing an article comprising: a hydraulically operated compression tool; a hydraulic fluid pressure source; said tool and said power source being operatively connected by two independent and isolatedfrom-each-other hydraulic media circuits, said circuits being in series with each other; first pressure sensitive bypass valve means associated with said pressure source for limiting the hydraulic pressure in one of said circuits to a first predetermined value; selectively operable cut-off valve means associated with said first bypass valve means for obstructing fluid flow therein; second pressure-sensitive by-pass valve means associated with said pressure source for limiting the hydraulic pressure in said one of said circuits to a second predetermined value greater than said first value; means operable to reduce the hydraulic pressure in said one of said circuits to a value less than the said first value; and resettable means responsive to said second value of hydraulic pressure for operating said means for reducing pressure.

2. A system according to claim 1 wherein one of said hydraulic circuits is included in a rigid dielectric tube.

3. A system according to claim 1 wherein one of said hydraulic circuits is included in a pair of spaced-apart, coaxial, rigid, dielectric tubes.

4. A system according to claim 1 further including a conduit between said hydraulic circuits wherein said hydraulic circuits are isolated from each other by means of a mechanical member displaceable within said conduit and in continuous circumferential contact therewith.

5. A system according to claim 4 wherein said displaceable member is a two faced disk, having one face in pressure contact With each hydraulic circuit.

6. A system according to claim 5 wherein said disk is of substantial thickness and further including at least a ring seal between said faces, said seal being adapted to effectively prevent the passage of said media past said disk.

7. A system for compressing an article comprising in combination: a hydraulically operated compression tool; a source of hydraulic fluid pressure; hydraulic connection means operatively connecting said tool and said source of fluid pressure for the transmission of fluid pressure therebetween; first pressure sensitive by-pass valve means associated with said source for limiting the fluid pressure in said connection means to a first value; selectively operable cut-01f valve means associated with said first bypass valve means for obstructing fluid flow therethrough; second pressure sensitive by-pass valve means associated with said source of limiting the fluid pressure in said connection means to a second value greater than said first value; pressure reducing means operable to reduce the fluid pressure in said connection means to a value less than said first value; and resettable means responsive to said second value of fluid pressure for operating said pressure reducing means.

8. A system for compressing an article comprising in combination: a hydraulically operated compression tool; a hydraulic pressure pump of the type which may be operated to produce hydraulic pressure, and stopped to relicve hydraulic pressure in a hydraulic circuit connected thereto; hydraulic circuit means operatively connecting said tool and said pump; first pressure sensitive lay-pass valve means associated with said pump for limiting the hydraulic pressure in said connection means to a first predetermined value; second pressure sensitive lay-pass valve means associated with said pump for limiting the hydraulic pressure in said connection means to a second predetermined value greater than said first value; electrically operable cut-01f valve means associated with said first by-pass valve means for selectively obstructing transmission of hydraulic pressure therethrough; electric motor means connected to said pump for supplying operating power thereto; a source of electric current; electric circuit switching means sequentially advanceable a step at a time to firstly connect said source of electric current to said electric motor means, to secondly connect said source of electric current to said cut-off valve means, and to thirdly disconnect said source of electric current from said motor means and said cut-oif valve means; and means responsive to said second value of hydraulic pressure for advancing said electric circuit switching means one step.

9. A system for controlling a hydraulically operated compression tool comprising in combination: a source of hydraulic pres-sure; hydraulic connection means operably connecting said source to a hydraulic compression tool; first means associated with said source for limiting the hydraulic pressure in said connection means to a first predetermined value; selectively operable means for preventing operation of said first limiting means; second means associated with said source for limiting the hydraulic pressure in said connection means to a second predetermined value greater than said first value; and means associated with said source for selectively relieving the hydraulic pressure in said connection means.

References Cited in the file of this patent UNITED STATES PATENTS 2,685,897 Vickery Aug. 10, 1954 2,870,605 Forster Jan. 27, 1959 2,973,625 Klingler Mar. 7, 1961 FOREIGN PATENTS 791,483 Great Britain Mar. 5, 1958

Claims (1)

1. 7. A SYSTEM FOR COMPRESSING AN ARTICLE COMPRISING IN COMBINATION: A HYDRAULICALLY OPERATED COMPRESSION TOOL; A SOURCE OF HYDRAULIC FLUID PRESSURE; HYDRAULIC CONNECTION MEANS OPERATIVELY CONNECTING SAID TOOL AND SAID SOURCE OF FLUID PRESSURE FOR THE TRANSMISSION OF FLUID PRESSURE THEREBETWEEN; FIRST PRESSURE SENSITIVE BY-PASS VALVE MEANS ASSOCIATED WITH SAID SOURCE FOR LIMITING THE FLUID PRESSURE IN SAID CONNECTION MEANS TO A FIRST VALUE; SELECTIVELY OPERABLE CUT-OFF VALVE MEANS ASSOCIATED WITH SAID FIRST BY-PASS VALVE MEANS FOR OBSTRUCTING FLUID FLOW THERETHROUGH; SECOND PRESSURE SENSITIVE BY-PASS VALVE MEANS ASSOCIATED WITH SAID SOURCE OF LIMITING THE FLUID PRESSURE IN SAID CONNECTION MEANS TO A SECOND VALUE GREATER THAN SAID FIRST VALUE; PRESSURE REDUCING MEANS OPERABLE TO REDUCE THE FLUID PRESSURE IN SAID CONNECTION MEANS TO A VALUE LESS THAN SAID FIRST VALUE; AND RESETTABLE MEANS RESPONSIVE TO SAID SECOND VALUE OF FLUID PRESSURE FOR OPERATING SAID PRESSURE REDUCING MEANS.

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