US3466729A - Apparatus for making clip-type electrical connections - Google Patents

Description

Sept. 16, 1969 w K C JR 3,466,729

APPARATUS FOR MAKING CLIP-TYPE ELECTRICAL CONNECTIONS Filed Nov. 8, 1966 3 Sheets-Sheet 1 D F. M Q i:

P 6, 1969 J. R. YVICKERY,'JR 3,466,729

APPARATUS FOR MAKING CLIPTYPE ELECTRICAL CONNECT IONS Filed Nov. 8, 1966 5 Sheets-Sheet 2 L 102 26 loo III In |44 P 16,1969 J. R. VICKERY, JR 3,466,729

APPARATUS FOR MAKING CLIP-TYPE ELECTRICAL CONNECTIONS Filed Nov. 8. 1966 3 Sheets-Sheet 3 United States Patent 3,466,729 APPARATUS FOR MAKING CLIP-TYPE ELECTRICAL CONNECTIONS John Roy Vickery, Jr., Clearwater, Fla., assignor to AMP Incorporated, Harrisburg, Pa. Filed Nov. 8, 1966, Ser. No. 592,773

Int. Cl. H01r 43/00 US. Cl. 29-203 ABSTRACT OF THE DISCLOSURE Apparatus for making a clip-type electrical connection between a wire and a terminal post, the apparatus being of the type comprising a mandrel and clip pusher for pushing the clip over the mandrel, against the wire, and onto the post. In accordance with the invention, wire grippers are provided which grip the wire and which hold the severed section of insulation. Grippers move from a first location adjacent to the mandrel to 'a second location remote from the mandrel and carry the scrap insulation to the second location at which it is disposed of.

'This invention relates to an apparatus for making cliptype electrical connections as shown generally in US. Patents 3,249,983 and 3,249,992.

As explained fully in the above-identified US. patents, clip-type electrical connections between wires and terminal posts are made by moving a generally channelshaped clip over a mandrel conforming to the informal cross-section of the clip, against a wire extending .into and opening in the mandrel, and onto the terminal post. The connector clip drags the Wire from the mandrel and onto the post so that when the clip comes to rest on the post, the wire is held against a surface of the post and in electrical contact therewith. This method of making electrical connections is frequently used with insulated wires and the mandrel is constructed such that when the clip moves against the wire and starts to drag the wire from the opening in the mandrel, the insulation of the wire is circumferentially severed and the end portion of the conducting core of the wire is pulled from its insulating covering. The scrap section of insulation remains in the opening and may be removed pneumatically in accordance with prior art teachings. Tools and automatic machines for making clip-type electrical connections are now Widely used and available in a variety of forms. Some of the presently available tools are pneumatically or electrically driven while others are manually powered.

The present invention is directed to an improved apparatus for making clip-type electrical connections and has a means for disposing of the scrap insulation which remains after the connection is made, a means for centering the wire in the tool with respect to the path of movement of the terminal clip, and has an improved actuating means driven by a pneumatic piston cylinder.

It is accordingly an object of the invention to provide an improved apparatus for making clip-type electrical connections. A further object is to provide a tool having means for transporting scrap insulation from the vicinity of the tool mandrel to a receptacle and depositing such sections of scrap insulating in the receptacle.

A further object is to provide a tool having a single actuating member, such as a piston rod, for both driving 7 Claims the clip pusher and for actuating the scrap disposal mechanism. A still further object is to provide a tool for making clip-type electrical connections having power actuated means for driving the clip pusher through the portion of the stroke during which a relatively high thrust is required and during which the insulation is stripped from the wire, but permitting manual actuation for the final portion of the stroke of the clip pusher during which the clip is moved to its final position on the terminal post.

These and other objects of the invention are achieved in a preferred embodiment comprising a hand tool for making clip-type electrical connections having a mandrel for guiding the terminal clip along its path of movement onto the terminal post and a clip pusher or push rod for pushing the terminal clip along its path of movement. The mandrel is provided with an opening into which the wire is inserted and a pair of wire gripping jaws are normally disposed in this opening so that the end of the wire is gripped after insertion. These vided for moving these jaws from their normal to their remote position during the operating cycle and immediately after the wire has been withdrawn from the end section of insulation. This end section of insulation is thus held until it is deposited in the waste receptacle and it cannot, therefore, fall into the apparatus being wired where it might later prove troublesome. The jaws, by virtue of their location in the mandrel opening, hold the wire exactly on the path of movement of the terminal clip and thereby prevent misalignment of the wire and terminal during the period when the connection is being made. The clip pusher is actuated by I a pneumatic piston-cylinder for most of its stroke and is manually actuated during the final portion of its stroke in order to permit exact manual control of the clip during the final portion of the operating cycle. The piston rod has a lost motion connection with a lever which moves the jaws from their normal position in the mandrel opening to their second position adjacent to the receptacle, the arrangement being such that the jaws are moved from their first position to their second position during the operating cycle and after the wire has been withdrawn from the end section of insulation.

In the drawings:

FIGURE 1 is a side view, with one side of the main housing removed, of a tool in accordance with the invention;

FIGURES 2, 3, and 4 are views similar to FIGURE 1, but showing only the actuating mechanism for the Wire gripping jaws and the clip pusher, the parts being shown in the positions they occupy during successive stages of the operating cycle;

FIGURE 5 is an enlarged sectional side view of an inner housing contained in the tool and in which gripping jaws, the clip pusher, and the associated structure are mounted.

FIGURE 6 is a fragmentary plan view showing the wire gripping jaws and illustrating the manner in which these jaws are held open prior to the initiation of an operating cycle;

FIGURE 7 is a view similar to FIGURE 5, but showing the positions of the parts after closure of the wire gripping jaws;

FIGURE 8 is a view similar to FIGURE 6, but showing the jaws in their closed condition;

FIGURE 9 is a fragmentary side view illustrating the operation of an adjustable stop for limiting the movement of the clip pusher;

FIGURE 10 is a fragmentary view showing the end portion of the tool of FIGURE 1 in alignment with a terminal post and illustrating the manner in which the terminal clip is pushed onto the post;

FIGURE 11 is a perspective view showing a typical clip-type electrical connection; and

FIGURE 12 is a fragmentary perspective view of a coupling between the clip pusher and a reciprocable yoke.

Referring first to FIGURE 11, a clip-type connection 2 between a terminal post 4 mounted on a panel or board 10 and the stripped end 6 of a wire 8 is made by means of a terminal clip indicated generally at 12. Terminal clips of this type comprise a web 14 from which sidewalls 16 extend, these sidewalls being so dimensioned that they can be telescopically slid onto the post and will remain on the post in embracing relationship thereto. The stripped end 6 of the wire is held between the web 14 of the clip and a surface of the post with the wire emerging from confined relationship at the lower end of the clip.

A preferred form of tool 18 in accordance with the invention (FIGURE 1) is of the pistol grip type having a handle 20 and a double acting pneumatic piston cylinder 22 on its upper end from which a piston rod 24 extends. A housing 26 extends forwardly from the upper end of the handle and contains the actuating mechanism for the tool as will be explained below. The piston cylinder 22 is controlled by means of a suitable valve 28 having a control trigger 30, the arrangement being such that the forward side (the right hand side in FIGURE 1) of the cylinder 22 is normally pressurized and the rearward end is pressurized and the forward side is exhausted to drive the piston rod 24 rightwardly when the trigger 30 is squeezed.

A block 32 secured to the end of piston rod 24 extends forwardly between the sides of the housing 26 and has a connecting block 34 adjustably secured to its underside. 1n the disclosed embodiment, a reduced lefthand end portion 31 of the connecting block 34 is contained in a channel in a depending flange of the block 32 and secured to this block by means of a locking screw 33. Screw 33 extends through an oversized opening in block portion 31 and is threaded into the depending portion of block 32. Precise adjustment of the position of block 32 with respect to block 34 is achieved by means of set screws 35 which bear against the sides of the screw 33 and which can be turned when the screw 33 is loose to change the relative positions of the two blocks.

The forward end portion 36 of the block 34 is similarly adjustably secured as at 37, 39 to a yoke member 38 having parallel arms (only one of which is shown in the drawing) which extend upwardly within the housing 26 and straddle a sub-assembly housing 40 disposed against the upper wall of the housing 26. The sub-assembly housing 40 has a base 42, and sidewalls 44 and is slidably contained in the main housing 26.

A pair of tweezer arms 46 (FIGURES 5-8) contained in housing 40 and disposed against the sidewalls 44 have inwardly directed end portions 52 on which there are provided wire gripping jaws 54. These inwardly directed portions of the tweezer arm are disposed in an opening 122 in the mandrel and function to hold the wire being connected to the terminal post. Arms 46 extend from a block 48 which is pivotally mounted on a pin 50, the

ends of which in turn are mounted, and extend beyond, in the sidewalls 44. The arms 46 have an inherent resilient tendency to move towards each other, to the positions of FIGURE 8, but are held apart at the beginning of the operating cycle by the reduced end portion 56 of a spreading member 58, see FIGURE 6. This spreading member is disposed between the arms 46, curves downwardly beneath the tweezer arms, and extends along the bottom wall 42 of the sub-assembly housing 40. Limited axial movement of this spreader member 58 with respect to the subassembly housing is permitted by a pin slot connection 60, 62 between the spreader rod 58 and the sidewalls of the housing. The end of the spreader rod 58 has an enlarged cylindrical boss 64 which fits into a suitable cylindrical bore in the rearward side of the sub-assembly housing, a coil spring 66 being interposed between the end wall of this opening and the opposed side of the boss 64 normally to bias the spreader member leftwardly to the position shown in FIGURE 7.

An additional pair of arms 68 extend downwardly from the bearing block 48 through slots (not specifically shown) in the bottom wall 42 of the sub-assembly housing 44. The lower ends of these arms 68 are connected by means of a pin 70 to a pair of connecting links 72, which are disposed on each side of the sub-assembly housing and which extend rearwardly and generally upwardly toward the top wall of the main housing. The ends of links 72 are provided with slots 74 and straddle the upper end 82 of a return lever generally indicated at 76. A pin 90 extends through the slots 74 and through an elongated slot 84 in the upper end of the return lever 76.

The return lever 76 is pivotally mounted intermediate its ends on a pin 78 extending between, and mounted in, the sidewalls of the main housing 26. A leaf spring 86 is mounted on this pin and extends upwardly towards, and bears against, the pin 90 so that the parts are normally biased to the position shown in FIGURE 1, that is, with the pin 90 at the limit of its rightward travel relative to the slots 74 in the lever 72. The ends of the pin 78 extend through slots in a bifurcated projection on the block 32. The lower end 92 of the return lever 76 is bifurcated and straddles the intermediate portion of block 34. A pin extending between the lower ends of this lever extends through an opening 96 in block 34 thereby to permit limited movement of the piston rod without effecting the lever 76 but to cause swinging of this lever during the final portion of the operating cycle as will be described below.

A leaf spring 98 is mounted against the bottom wall of the main housing and has one arm 102 which extends upwardly and beneath the lower end of the lever 76. This end of this arm functions as a frictional drag on the lever 78 and prevents its premature movement during the initial portion of the cycle. The other arm of this spring extends upwardly and supports the underside of the previously identified yoke 38.

The gripping jaws on the ends of the tweezer arms 46 are opened during the final portion of the operating cycle by means of a fixed wedge member 106 extending from a block 108 mounted between the sidewalls of the main housing. During rearward movement of the sub-assembly housing 40, the jaws, in the closed condition and having a short section of scrap insulation gripped therebetween, move relatively against this wedge which causes them to be sprung apart whereby they deposit the scrap insulation in a receptacle 110. This receptacle is in the form of a plastic closed-end container and is mounted on depending spring members 112 which in turn are secured to a front mandrel section 118. A relatively heavy plastic curtain 114 having a slit-like opening therein is provided on the receptacle. As will be explained below, the scrap insulating is pushed through this curtain and into the receptacle.

Referring now to FIGURE 7, the mandrel is formed in two sections 116, 118 which are separated by a gap 122 in which the gripping jaws 54 are mounted and into which the wire 8 is inserted. The back section 116 of the mandrel is mounted on the sub-asembly housing and the front section has a base portion 120 which is mounted on a pair of ears 124 extending from the sidewalls 44 of the sub-assembly housing. Each mandrel section is generally T-shaped in cross-section as disclosed in the above-identified Cobaugh patent so that the terminal clip can be pushed over the mandrel, past the wire 8 which is located in the opening 122 and onto a terminal post as shown in FIGURE 10. The push rod 144 is of the general type disclosed in the U.S. patent to Long 3,249,992, and is disposed against the underside of the top wall of the main housing. The rearward end 147 of this push rod is secured to the upper ends of the arms of the yoke 38 (see FIGURE 12) so that rightward movement of this yoke member as shown in FIGURES 2-4 will result in rightward movement of the push rod. The push rod is generally channel-shaped in cross-section and is adapted to straddle a strip of terminal clips 162 which is fed from a suitable reel 160 mounted on the upper surface of the tool and led downwardly through the upper wall of the main housing. Advantageously, an ear 148 is struckup from the rearward end of the push rod to provide a guide surface for the strip of clip, see FIGURE 12. The push rod engages the leading clip of the strip as indicated at 146 (FIGURE The previously identified Long Patent 3,249,992, shows one of the type of spring which can be mounted on the push rod to engage this leading clip.

The leading clip of the strip must be separated from the next adjacent clip when the leading clip is applied to a terminal post and this is acomplished by breaking the leading clip from the strip in the manner generally disclosed in the Long Patent 3,249,992. In the disclosed embodiment, a stop pawl 126 is provided on the end of an arm 127 in the housing 40 and between the tweezer arms 46. The arm 127 is pivotally mounted on a pin 128 extending between the sidewalls 44 of the sub-assembly housing 40 thereby to permit movement of the pawl between the positions shown in FIGURES 5 and 7. Arm 127 has a depending end portion 130 which extends into a relatively short notch 132 on the upper surface of rod 58.

When the parts are in the position of FIGURE 5, the depending portion 130 of arm 127 is in back of the notch 132 so that the pawl 126 is lowered out of engagement with the strip of terminal clips. The strip can thus be moved rightwardly while the pawl is lowered between push rod as explained above. Shortly after rightward movement of the push rod and the strip of clips commences, the rod 38 moves leftwardly under the influence of the spring 56 and the pawl 127 moves upwardly under the influence of a suitable leaf spring (not specifically shown). The end of the pawl then lodges between the leading clip of the strip and the next adjacent clip so that upon further rightward movement of the clip pusher, the leading-clip is pushed further along its-path over the mandrel and broken away from the next adjacent clip.

A funnel-like wire guide 136 is provided above the opening 122 on the end of an arm 138 which extends from a block 140 secured to the top wall of the main housing. Advantageously, a screw extends through an opening in the arm 138 and has a nut 142 on its end to adjust the position of the wire guide funnel 136 relative to the upper surface of the push rod. This member 136 functions as a back-up or support'mem'ber for the push rod and assists in guiding the push rod along a straight line path during its movement indiacted in FIG- URES 2-4.

As will be explained below, the sub-assembly housing 40 is moved relatively inwardly with respect to the main housing during thefinal portion of the operating cycle. During this portion of the cycle, the clip is moved to its final location on the terminal post and the extent of this relative movement determines the =final position of the clip on the post. It is desirable to provide a positive stop limiting the relative inward movement of the sub-assembly housing 40 in order to precisely fix the position of the clip on the post, particularly where several connections are being made on a single terminal post. Accordingly, I provide an adjustable stop member showing in FIGURE 9, a lever pivoted to the wall of housing 26 and having a pin 152 extending into an irregularly shaped opening 156 in the sub-assembly sidewalls 44. This opening 156 has three spaced-apart pockets 158 on its right hand side which are adapted to receive the pin 152 during relative leftward movement of the wall 44 with respect to the wall of the main housing 26. It will thus be apparent that the relative movement of the sub-assembly housing wall 44, and, therefore, the sub-assembly housing, will be limited depending upon the position of the pin 156. If the lever 150 is swung to the left in FIGURE 9, the pin will be in its lowermost position and the movement of the subassembly housing will be limited by the lowermost pocket 158. The two remaining pockets provide for a slightly greater amount of movement of the sub-assembly housing.

In use, the parts will normally be in the positions shown in FIGURE 1 at the beginning of the operating cycle with the piston rod 24 in its fully retracted position. It will be noted that at the beginning of the cycle, the block 34 is also at the limit of its leftward movement and the right hand side 96a of the opening 96 bears against the pin 94 thereby holding the lever 76 at the limit of its clockwise movement. When this lever is in this position, its upper end bears against the rearward side of the enlarged cylindrical end 64 of the control rod 58 and thereby holds this control rod at the limit of its rightward movement so that the spring 60 is compressed and the reduced end portion 56 of the rod is between the tweezer jaws 54 holding them in their spread-apart condition. The operator can thus insert the wire as indicated in FIGURE 1 downwardly into the opening 122 and between the jaws 54.

After inserting the wire as shown in FIGURE 1, the operator squeezes the trigger 30 causing rightward movement of the piston rod 24 to the limit of its travel. It should be mentioned that the cylinder 22 is relatively small and only a relatively short stroke is required as will be apparent from an inspection of FIGURES 2-4. During initial rightward movement of the piston rod, the side 96a of the opening 96 moves away from the pin 94 in the lower end of the lever 76. The rod 58"then moves leftwardly under the influence of spring 66 and the lever 76 is swung through a slight counterclockwise arc. The leftward movement of the rod 58 also has the effect of withdrawing the reduced end portion 56 of this rod from between the jaws 54 thereby permitting these jaws ,to close into gripping engagement with the wire under the influence of their inherent resilient tendency to move towards each other. The wire thus gripped is accurately centered with respect to the path of movement of the clip over the mandrel.

The initial counterclockwise movement of the lever 76 causes its lowered end to move against the upper surface of the spring 102, which, as previously mentioned, functions as a frictional drag preventing further undesired swinging of this lever about its pivotal axes 78 until a later stage of the cycle. The initial rightward movement.

of the piston rod 24 during the early part of the cycle also has the effect of moving the yoke 38 rightwardly, and, therefore, the clip pusher moves rightwardly from the position of FIGURE 2 to the position of FIGURE 4. During such movement, the terminal clip is moved over the mandrel, past the opening 122, and up to the end of the mandrel as shown in FIGURE 4.

During the final portion of the stroke of the piston rod, the lefthand side 96b of the opening 96 in block 34 moves against the pin 94 in the lower end of the lever 76. Thereafter, and upon further movement of the piston rod and block 34, the lever 76 is swung through a counterclockwise arc moving the pin 90 on its upper end to the limit of its travel in the slots 74 of the arms 72 (FIGURE 2). Upon further movement of the piston rod, FIGURES 3 and 4, and further swinging of the lever 76, the lower arms 68 extending from the boss 48 are swung through a clockwise are about their pivotal axes 50 and the tweezer jaws 54 are swung downwardly along an arcuate path until they are in alignment with the window or slit in the apron 114 of the receptacle 110.

When the parts are in the position of FIGURE 4, the operator locates the end of the mandrel section 118 against the post to which a connection is to be made (F IG- URE and gently pushes the tool forwardly to move the sub-assembly housing 40 inwardly relative to the main assembly housing. Since the push rod, however, is secured to the upper ends of the yoke arms 38, it does not move relative to the main assembly housing, and, therefore, moves relatively downwardly over the terminal post as generally explained in the above-identified Long patent. The operator can push the tool only to the extent allowed by the position of the stop pin 152 so that if he is putting on the third clip of a three-high stack of clips on a given post, he will have this stop pin set in its lowest position.

During relative inward movement of the sub-assembly housing 40 with respect to the main housing 26, the jaws 54 on the ends of the tweezer arms 46 will have been lowered and will be disposed in front of (i.e., to the right in FIGURE 1) the wedge member 106. The inward movement of the sub-assembly housing thus results in a relative movement of these jaws and the curtain 114 towards the wedge member. During such movement, the wedge member 106, (which is secured to the main housing 26 and which does not move) pushes the section of scrap insulation from between the jaws, through the slit in the curtain 114, and into the receptacle 110.

After the tool has been pushed forwardly, that is, to wards the board 10, to locate the clip connection in its desired position on the terminal post, the operator merely withdraws the tool from the board and releases his grip on the trigger 30. The valve 28 will then function to exhaust the lefthand side of the cylinder 28 and pressurize the right hand side thereby retracting the piston rod 24 and moving the part back to the position of FIGURE 1. The sub-assembly housing will be slid rightwardly from the position of FIGURE 4 to the position of FIGURE 1 by the upper end of the lever 76 which will be swung in a clockwise arc by the action of the block 34 on the pin 94. During final portions of the retraction of the piston rod, the lever 76 will press against the enlarged end 64 of the control rod 58 thereby to compress the spring 66 and drive the spreader member forwardly between the jaws 54 in preparation for the next operating cycle.

A significant advantage of an apparatus in accordance with the invention is that small chips of scrap insulation are removed and deposited in the receptacle during the operating cycle. These chips can be frequently quite troublesome particularly where electrical connections are being made to extremely small terminal posts and small bits of scrap insulation can not be tolerated between the posts. It is also necessary to remove such insulation chips when delicate electronic apparatus are being wired since such chips might tend to interfere with the functioning of the circuits of the apparatus.

The actuation system for the disclosed form of tool, aside from the insulation chip or scrap removal features, offers certain advantages in that the portion of the stroke of the push rod during which the clip is driven to the end of the mandrel is achieved by the pneumatic pisto ncylinder 22, 24. It is during this portion of the stroke that a relatively high thrust is required and a power assist device for driving the piston rod is highly desirable. However, during the final portion of the stroke, the operator relies on his own feel of the tool to push the clip into the post. It is desirable to rely on manual force for this portion of the stroke for the reason that damage might result to the clip or to the finished connection if a relatively high thrust or force is applied to the push rod. An experienced operator, on the other hand, can push the terminal clip with the wire thereon gently onto the terminal post and avoid damage to the connection during this critical portion of the operating cycle.

Changes in construction will occur to those skilled in the art and various apparently different modifications and embodiments may be made without departing from the scope of the invention. The matter set forth in the foregoing description and accompanying drawings is offered by way of illustration only. The actual scope of the invention is intended to be defined in the following claims when viewed in their proper perspective against the prior art.

What is claimed is:

1. An apparatus for making a clip-type electrical connection between a wire and a terminal post comprising a mandrel and clip moving means for moving a clip over said mandrel, against a wire, and onto a terminal post, the improvement comprising wire gripping means normally disposed adjacent to said mandrel for gripping said wire during movement of said clip over said mandrel, and means for moving said wire gripping means to a location remote from said mandrel whereby, after movement of said clip past said mandrel, the insulation of said wire is severed adjacent to its end and said wire is pulled from the end section of insulation, and said gripping means retains the end section of scrap insulation,

and upon movement of said gripping means to said remote location, said section of scrap insulation is carried from the vicinity of said mandrel.

2. In an apparatus for making clip-type electrical connections and comprising a mandrel for guiding a terminal clip along a predetermined path, an opening in said mandrel for reception of the end portion of an insulated wire, and clip moving means for moving a terminal clip over said mandrel and onto a terminal post, the improvement comprising: closable wire gripping means for gripping said wire, said gripping means being movable between a first position in said opening and a second postion remote from said opening, said gripping means being in said first position prior to movement of a terminal clip over said mandrel, means for closing said gripping means when said gripping means is in said first position whereby the end portion of a wire positioned in said opening is gripped, and means for moving said gripping means to said second position after movement of siad clip past said opening whereby, said gripping means holds the section of insulation stripped from the end of said wire and carries said section to said second position, and discharge means for discharging said section of insulation at said second position whereby, said section is disposed of at a location remote from the connection being made.

3. Apparatus as set forth in claim 1 wherein said gripping means comprises gripping jaws, jaw moving means for moving said jaws from said first position to said second position, actuator means for actuating said clip moving means, said jaw moving means being actuated by said actuator means.

4. Apparatus as set forth in claim 1 including receptacle means at said second position, said discharging means comprising means for transferring said section of insulation from said gripping means to said receptacle means.

5. Apparatus as set forth in claim 1 wherein said clip moving means comprises a reciprocable clip pusher movable over said mandrel, reciprocable actuator means for actuating said clip pusher, and means actuated by said actuator means for closing said gripping means and moving said gripping means between said first and second positions.

6. Apparatus as set forth in claim 5 wherein said gripping means comprises normally closed tweezers pivotally mounted for movement between said first and second positions, a spreader rod between said tweezers, said spreader rod being held between said tweezers when said tweezers are held open by reciprocable actuator, and said spreader being withdrawn from between said tweezers during movement of said actuator to close said tweezers.

7. Apparatus as set forth in claim 6 including pivoted lever means for swinging said tweezers about their piv- 10 otal axis between said first and second positions, and means effective between said reciprocable actuator and said lever means for pivoting said lever means during movement of said actuator means.

References Cited UNITED STATES PATENTS 2,667,094 1/ 1954 Potter.

3,239,918 3/1966 Cobaugh 29628 3,249,983 10/ 1966 Cobaugh 2933 3,249,992 10/ 1966 Long 29203 THOMAS H. EAGER, Primary Examiner US. Cl. X.R.

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