US2020402A

US2020402A - Test pick

Info

Publication number: US2020402A
Application number: US669438A
Authority: US
Inventors: Edwards Paul Griffith; Clutts Charles Edward
Original assignee: American Telephone and Telegraph Co Inc
Current assignee: AT&T Corp
Priority date: 1933-05-04
Filing date: 1933-05-04
Publication date: 1935-11-12
Anticipated expiration: 1952-11-12

Description

' which is made of 'an insulating material such as- Patented Nav. 12, 193s Paul Griith Edwards, Millburn, and (Zhan-les` Edward Clutts, Clifton, N. J., assignors to American Telephone and Telegraph Company, a corporation of New York Application May 4, 1933, Serial No. 669,438.

. 4 claims. (ci. zoo-1s) UNITI-:o STATES PATENT OFFICE 'I'his invention relates lto electrical apparatus collar 6 is permanently fastened to the sleeve' 2'4 such as keys, switches, test picks and the like.

One form of test pick quite generally used for making temporary electrical connections to various conductors forming` different circuits or different pieces'of apparatus, consists of apointedV one circuit toanother circuit, both of which are used for testing purposes, unless a key or switch,

or thelike, is'employed in addition to the pick. To overcome these limitations this invention has been evolved'and it consists of a novel form of test pick which may be viewed in general as a unitary structure combining .the features of the old fashioned test pick and a key or switch, or the like. l

This invention will be better understood from the detailed description hereinafter following when read'in connection with the accompanying drawing, in which Figures l and 2 .show two embodiments of the invention given merely for the purpose of illustration. v

Referring'to Fig. `1 of the drawing, the reference character'l I designates a .shell or`handle libre, bakelite, etc., and it is preferably` cylindrical in shape. The shell I surrounds two sleeves 2 and 2'. both of which are metallic and therefore electrically conductive. .The-sleeves 2 and 2' are also cylindrical in shape, and insulated from l insulator 3 and the collar 9 which is mounted on andvpermanently fastened to the pick 4 lby Ameans of a set-screw, as shown. 'I'he coil spring l serves normally to maintain the pointed end of the pickas far to the right as possible.

A collar 5 is also mounted on and permanently Afastened toanother section of the pick 4 by means of a set-screw, as shown. Still another by means` of a set-screw, and it will be evident that the collar 6 is normally insulated from the pick 4 bythe air space therebetween. The collars 5 and 6 serve both as metallic contacts and 5 as stops for limiting the movement of the pick 4 in one direction, i. e., to the right. A plug I2 is inserted at the base of the shell I, i. e., at its left, and within the center of the plug I2 is inserted a metallic screw designated 'I which may 10 be equipped at the end distant from its head with a contact point A. The unpointed or left-hand end of the pick 4 is also equipped with a centrally located contact point B which is directly in line with the contact A. 'I'he left-hand end l5 of the sleeve 2 may carry a lug or terminal such as I0 which is employed for making one of the electrical connections to the testing or other apparatus (not shown), The head of the screw 7 .may be employed for making another electrical 2o connection to the latter apparatus -or to other testing apparatus. It will be noted that the contact point A limits the movement'of the rod or pick 4 in the opposite direction, i. e., to the left, and in its extreme position the contacts A and B are conductively connected to each other.

The conductor extending to the lug I0 may be considered as part of one of two circuits incorporated in the testing apparatus above mentioned and this circuit may be termed. for convenience of description, the first circuit. The conductor extending to the head of the screw 1 may be considered as part of the other of the two circuits of the testing apparatus and this may be termed the second circuit. v

If it is desired to connect the iirst circuit of the testing apparatus to a circuit to be investigated or to one of its conductors or terminals, and then to transfer the circuit to be investigated to the second circuit of the testing apparatus, it v4.0 will be necessary to bring the pointed or righthand end of the pick 4 against and in contact with the circuit to be investigated. This will establish a conductive path from the lug II! along the sleeve 2' through collars 6 and 5 to the tip 45 of the pick 4. Inasmuch as the conductor extending to the lug I0 is part of the rst testing circuit, then-the latter conductive path, just described, will establish an electrical connection between the first testing circuit and the circuit to be investigated.

at the head ofthe screw '1, then the handle or shell I of the arrangement will be pressed or pushed forward, i. e., to the right, so that the pointed end of the pick 2 will be in contact with one -of the conductors of the circuit to be investigated under pressure. The pick l will be moved to the left with respect to the handle or shell I and in its extreme position at the left the contacts A and B will be closed. Immediately after the collar 2 breaks its contact with the collar 2, the first testing circuit will be dissociated from the circuit to be investigated. And-upon the subsequent closure of contacts A and B. the circuit to be investigated will be connected to the second testing circuit, the intermediate conductive path comprising-the pick 2, contacts B and A, the screw 1 and the conductor connected to the head of screw 1. When the pressure applied to the handle I becomes released, the pick 2 will be moved to the right with respect to the handle or shell I, so as to break the circuit between the 'contacts A and B. 'Ihe spring 2 will return-the pick to its normal position, which is las far to the right as collar 2 will allow it to go, the extent of the motion of collar 2 to the right being determined by the location'of the collar 2.

The time required for transferring the connection of the circuit to be investigated from the nrst testing circuit extending to the lug I2 to the second testing circuit which extends to the head of the screw 1, is dependent upon a number of factors such as the spacing and relative locations of the collars 2 and 2, the'maximum distance between contacts A Iand B, which may be varied by changing the length of the pick 2, the Speed with which the handle is depressed, the sise and relative proportions of the spring 2, and 0n.

mg. 2 snows another type Jr-test pick. A'rms arrangement includes a cylindrical shell or handle 2| which may be of insulating material, one end of which, i. e., at the right, is internally threaded. A bushing 22, also of insulating mascrew-threaded external surface which engages the member 22, the member 22 being cup-shaped and internally threaded within the cupped portionsoastoengagetheexternalscrewthreads `at the unpointed end of thepick 22. The member 22 is' made of a conductive substance such as bi'assorthelike anditiseonical or otherwise pointed in shape at its left-hand end.

- s cenar-21 is mounted upon the piek :s with;

in theshell or handle 2|, this collarbeing permanently fastened to some point along the outer surface of the pick 22. A set-screw may be used for fastening the collar 21to the pick 22, as shown. Another collar 22 is permanently fastened to the shell 2| by means of a set-screw as shown and this echar has a wide, central aperturewhich may be circular in shape.l A helical spring is positioned about the pick 22 and within l the central aperture of the collar 22, this spring being located between

collars

22 and 21. This ,spring produces a continuously acting pressure against the left-band side of the movable collar 'hand sideoftheeollar 22. This'ill tion of pressure to the shell 2| so as to allow the 5 left-hand side of the collar 21 to contact at its edge one side of the collar 22 and when-'this happens. the pick will be located as far to the left as possible.

The shell or handle 2| also surrounds a Jack'lo arrangement which includes three springs designated 22, 2| and 22, the

springs

22 and 22 being relatively iixed and immovable while the spring 2| may be moved laterally at its right-hand end so as to contact either of the

springs

22 or 22. At their left-hand ends the springs 22. 2| and 22 are spaced from each other by insulators 22. The insulators 22 and the springs 22, 2| and 22 are fastened together within blocks of insulation 22 bymeans of a pair of screws 22 whichmay be'zo placed within a corresponding Pair of bushings 22 which are made of insulating material, the screws 25 being threaded so as to engage' the base of the insulating member 22, as shown.

- Three

ymetallic lugs

22, 21 and 22 are conductively 25 connected to the springs 22, 2| and 22 and each of these may be connected to a wire or conductor. The insulating member is xed in position within the shell 2| by means of a number of set-screws which are designated 22. 80 The right-hand end of the spring 2| is spoonshaped so as to be slidable along the pointed outer surface of the metallic member 22. The spoonshaped end of the spring 2| is always in contact with the member 22 although its location about 25 the outer surface 0f this member may be changed depending upon whether or not pressure is applied to the shell 2|. When no pressure is applied to the shell 2|, the pick 22 will be located as far to theright as possible with respect to the shell 2| 40 and the springs 2| andl 22 will/be conductively connected to each other. When the springs 2| and 22 are conductively connected to each other.

lspring2'2willbecompressedandthepick22nill20 be moved to the left with respect to the shell 2| until .the

collars

21 and 22 meet each other. At the same time, the spoon-shaped end of the spring 2| will be lifted upon the steeply' graded outer surface of the cup-shaped member 22, thereby 56 first breaking the contact between springs 2| and 22v and subsequently making contact betweemthe springsl 2| and` 22. When this occurs, Qthe conductive path will include the pick 22, the cupshaped member 22, the parallel paths established 00 by springs 22and 2| and the

lugs

22 and 21 which are conductively connected to these springs, respectively, vWhenthepressureappliedtothoshell2| is' subsequently released, the spring 22 will cause 25 the pick 22 to move to the right as before, the motion to the right being terminated w e right-hand side of the member 22 meets While this invention has been shown and described in certain particular arrangements merely for the purpose of illustration, it will be understood that the general principles of this invention may be applied to other and widely varied organizations without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is:

1. A test pick comprisinga handle of insulating material which is cylindrical in shape and lined with a metallic member having a hollow center, a metallic rod pointed at one end and concentric with the handle, means including a spring for retaining the unpointed end of said rod in a predetermined position within the hollow section of said handle, a fixed electrical terminal insulated from the lining of said handle, the handle being depressible-in the direction of the pointed end of said rod so as to change the relative position oi said rod with respect to said handle by a predetermined distance and to contact said iixed electrical terminal, and mutually independent electrical circuits completed from the rod to the metallic lining of said handle or to` said xed electrical terminal when it reaches its two extreme positions, said metallic rod being alone common to said mutually independent electrical circuits.

2.,A testing device comprising a metallic rod pointed at one end, an insulated holder having a hollow center and a metallic lining, the unpointed end of said rod being slidably mounted within the center of said holder, means for normally maintaining the pointed end of said rod a predetermined distance away Irom said holder and in electrical contact with the lining of said holder, a fixed terminal normally spaced from the unpointed end of said rod, and means responsive to the application of pressure to the holder to reduce the distance between the pointed end of said rod and said holder by a predetermined amount so that said rod will make electrical contact with said fixed terminal.

3. A manually operated unitary test pick comprising a handle of dielectric material having a hollow central section, a metal pick, means for 5 sliding said pick through the central section of said handle, a rst conductive element limiting the movement of said pick into the central section oisaid handle, means including a second conductive element limiting the movement of said pick out of the hollow central section oi said handle, and means for normally retaining said pick in contact with said second conductive element.

4. A test pick comprising a hollow cylindrical shell of insulating material, two metallic linings for said shell, both of the same internal diameter,

a stationary insulator located within said shell and spacing one oi said linings above the other, a plug o! insulating material located at the lower end of said shell, a long metallic rod pointed at one end, said insulator and said plug having concentric apertures through which said rod may slide, a plug of insulating material having a central aperture located at the upper end of said shell, a conductive element passing through the aperture of the latter plug so that the unpointed end of said rod may contact therewith, a collar permanently fastened to said rod, said collar being positioned between the plug at the lower end of the shell and said insulator, a coil spring interposed between said collar and said insulator and around said rod, and two concentric metallic collars, one of which is permanently fastened to said rod above said insulator and the other fastened to the upper lining so that they may. electrically contact each other and limit the movement of said rod.

PAUL G. EDWARDS.

CHARLES E. CLUTTS.