US2309849A - Racket stringing device - Google Patents

Description

Feb. 2, 1943.

R. A. KAUSAL EI'AL RACKET STRINGING DEVICE 4 Sheets-Sheet 1 Filed Jul' 29, 1940 INVENTOR:

I Q RUDOLPH/4i KAUSAL "A lilll lll illllllillr E c K (jg/1L 2 TTORNEYS Feb. 2, 1943. R. A. KAUSAL ETAL 2,309,849

RACKET STRINGING DEVICE Filed Jul 29, 1940 4 Sheets-Slieet 2 INVENTOR: RUDOL PH A. KAusAL KEN/v5 TH C. K AUSAL I ATTORNEYS.

Feb. 2, 1943. R. A. KAUSAL ETAL 2,309,849

- RACKET smmeiue DEVICE I Filed July 29, 1940 4 Sheets-Sheet s III/II I Ma IIIIIIIIIIIIIIIIIIII/IA INVENTOR: Ruooz. PH A. KA USAL. K ENNE TH C. KAU$AL b 1943- I R. AgKAUsAL EIAL RACKET STRINGINQDQEVIVCE Filed July 29, 1940 4 Sheets-Shebt 4 INVENTOR: RUDOLPH A.K'AuSA/ V KENNETH C. KA USAL Patented Feb. 2, 1943 OFFICE 7 2,309,849 BACKET STRINGDIG DEVICE Rudolph A. Kausal and Kenneth C. Kausal,

- St. Louis, Mo.

Application July 29, 1940, Serial No. 348,088 17 Claims. (01. 5273-73) This invention relates to improvements in racket-stringing devices that are operated by pneumatic pressure. More particularly, the invention relates to improvements in pneumatioally operated racket-stringing devices that are substantially self-contained.

It is an object of the present invention to provide a simple and eflicient pneumatically operated racket-stringing device.

Pneumatically operated racket-stringing devices have been known for some time, but these devices have not been substantially self-contained. The operation of such devices necessitated the employement of an air compressor or similar means to maintain the necessary stringing pressure throughout the stringing operation. Because of the employment of an air compressor in the operation of this type of racket stringer, the initial cost and operating expense are almost prohibitive. In addition, the employment of an air compressor adds another device that must be taken care of, and it makes the operation of this type of racket-stringing device quite bothersome. The invention obviates the difliculties outlined above by providing a substantially self-contained racket-stringing device that maintains throughout the stringing operation any pressure initially impressed upon it. It is, therefore, an object of the present invention to provide a substantially a self-contained, pneumatically operated, racketstringing device.

Various types of string pullers have been used on racket-stringingdevices, but few of them have been entirely satisfactory. Many of them are provided with ridges on their inner faces which serve to hold the string, but these ridges tend to cut the string and thereby weaken it. Other string pullers require the operator to hold the string in his hand, or necessitate the tying of a hitch around the string puller. These string pullers are objectionable because they increase the time required to string a racket, require the employment of a semi-skilled worker, and make the stringing operation unnecessarily bothersome. Other string pullers have been used which have no ridges on their inner faces, but these are objectionable because the faces must be pressed together so tightly to hold the string, that the faces of the string pullers crush the string. The present invention obviates these difficulties by providing a string puller that has a snubbing post and clamp thereon. Such a combination reduces the amount of pressure that must be exerted on the string by the clamp to hold it firmly. It is,

therefore, an object of the invention to provide a. string puller that holds the string securely with a relatively small pressure exerted thereon.

Other objects and advantages of the invention will be shown and described in the drawings and accompanying description.

In the drawings and accompanying description, a preferred form of the invention has been shown and described, but it is tobe understood that the drawings and accompanying description do not limit the invention and that the invention will be defined by the appended claims.

In the drawings, Fig. l is a broken section of a racket-stringing device made in accordance with the principles of the invention and shows in perspective the elements of the device in assembled relation. V

Fig. 2 shows a side View of a part of a preferred form of string pullerto be used with racketstringing devices.

Fig. 2a. shows an end view of the string puller of Fig. 2, I

Fig. 3 is an inverted View of the top of the racket-stringing device shown in Fig. 1 and shows in perspective the arrangement of the parts mounted on the under side thereof.

Fig, 4 is another inverted view of the top of the racket-stringing device and shows in perspective the upper side thereof.

Fig. 5 is an enlarged end view of one pair of projections on the under side of the top of the racket-stringing device, that is bridged by rollers that slidably support the string-pulling bar. Fig. 6 is an enlarged end view of the other pair of projections on the under side of the top of the racket-stringing device, that is also bridged by rollers that slidably. support the string-pulling bar.

Fig. 7 is a view of the elements of the pressure system used in a preferred form of racket-stringing device.

Fig. 8 is a cross-sectional view of a check valve used in the pressure system. 7

Fig. 9 is a cross-sectional view of a hand operated cut-off valve used in the pressure system.

Fig. 10 is a cross-sectional view of a pressure operated cut-01f valve used in the pressure system.

Fig. 11 is a plan view of a portion of a support for a racket head.

Fig. 12 shows a plan View of a clamp used to secure the racket to the racket support shown in Fig. 11.

Fig. 12a is a side view of the clamp of Fig. 12.

Fig. 13 is a threaded member and a wing nut therefor, that cooperate withthe clamp shown in Fig. 12 to hold a racket head to the racket support shown in Fig. 11.

Fig. 14 shows a plan view of another clamp that is used with the threaded member and wing nut shown in Fig. 13,

Fig. 14a is a side view of the clamp of Fig, 14.

Fig. 15 is a plan view of a racket support that may be used with the threaded member in Fig. 13 and the clamp in Fig. 14.

Fig. 16 is an end view of a string clamp that may be used with racket-stringing devices.

Fig. 17 is a side View of a string clamp that is mounted on the clamp guide and support which is supported on the guide plate of the racketstringing device.

Fig. 18 is a perspective view of the handle that is used with the string clamp shown in Fig. 17.

Fig. 19 is a side view of one of the guide clips used to form a string clamp guide shown in Fig. 17.

Referring to the drawings in detail, the base of the racket-stringing device is denoted by the numeral 26. Attached to this base are side members 22 that support the top 24 of the device. The upper side of top 24 has two raised portions thereon. One raised portion 26 is annular in shape and the other portion 28 is circular in shape and is positioned in the center of the annular portion 26. The circular portion 28 is drilled and tapped to receive a bolt 30 which rotatably secures guide plate 32 to top 24. The guide plate 32 has bolts 34 secured to the under side thereof that slidably engage the annular portion 26. The engagement between the bolts 34 and the annular portion 26, maintains the guide plate 32 in a horizontal position during the rotation thereof. Also mounted on the. under side of guide plate 32 is a bar 36 that is rigidly secured to the guide plate 32 by bolts 38, and is rotatable therewith. The bar 36 has a hole in the center thereof that encircles and rotatably engages the bolt 36 and permits rotation of the bar with the guide plate 32. The bar 36 has racket supports 42 mounted thereon that are secured thereto by bolts 44. These racket supports have openings in the bottoms thereof that are similar to the profile of bar 36, but are slightly larger; thereby making it possible to slide the supports along the bar. Each of the racket supports 42 has a plane surface 46 on the upper end thereof and a racket stop 48 on the plane surface. The racket stop 48 and the racket support 42 have a groove 50 in one face thereof that receives a threaded member, wing nut, and racket clamp assembly that may be tightened to secure the racket to the racket support. The threaded member, wing nut, and racket clamp assembly is formed by inserting threaded member 52 through the hole 6| in clamp 69, and threading wing nut 54 onto the end of member 52.

To secure the racket to the support, the assembly is loosened by the rotation of wing nut 54, and is then slipped into the groove 56 in the racket support 42. This places clamp 60 on the racket head and places the bent portion 53 of threaded member 52 underneath the racket support 42. The wing nut 54 is then rotated unti1 the racket is held securely against the support 42. Another form of racket support 40 and clamp 58 that may be used are shown in Fig. 11 and Fig. 12 respectively. These are also used with the threaded member 52 and the wing nut 54. The threaded member 52 is inserted in the hole in the racket support 40 so that its bent portion 53 is uppermost. The clamp 58 is then slipped under the bent portion 53 so that the recess 56 therein engages the straight portion of member 52, and the wing nut 54 is rotated and the assembly thereby tightened. The use of these clamps avoids the cutting of the racket strings which is experienced with other racket-stringing devices. After a racket has been strung on a racket-stringing device, the racket must be lifted from the racket supports. Where the racket supports have threaded projections to which clamps are secured during the stringing operation, the strings of the racket may contact the threads on the projections and be injured severely by such contact. The invention obviates such an occurrence by having a clamping device that is smooth wherever it contacts the strings of the racket, and is made so that the few threads thereon cannot contact the strings of the racket. In addition the clamps are preferably provided with a rubber or leather pad on the under side thereof that protects the wood of the racket from injury. Although many forms of racket clamps may be used, the two novel forms that are shown and described above are preferred. By use of these clamps, the time required for the stringing operation is materially reduced.

One of the racket supports 42 has an additional racket-holding element thereon which consists of a U-shaped yoke 64 that is secured to lugs 66 on the racket support by a pin 68. The pin and yoke are preferably made so that the yoke may readily be released and removed from the racket support. the top thereof that is drilled and tapped to receive a wing bolt 10. The yoke 64 and wing bolt 18 cooperate with clamps 66 and wing nuts 54 to secure racket I2 to the racket supports 42.

The strings 14 in racket 12 are held during the stringing operation by string clamps I6 and 18. These clamps consist of elements and 82, each of which has an opening 84 in the lower portion thereof. The lower portions of the elements BI! and 82 are arranged to slidably engage each other in a hinge-like fashion. When these elements are mounted on bar 86. they act as a hinge and permit movement of the upper portions of the elements to and from each other. The movement of the upper portions of elements 88 and 82 is guided by a dowel 88 that is secured to element 86 and engages an opening 90 in element 82. The dowel 88 is encircled by a coiled spring This spring is positioned in a. recess 94 in the elements 86 and 82 and tends to separate their upper ends. Such an arrangement permits the ready insertion of a string into the stringing clamps since the spring forces the ends of the clamps apart. The clamps may be tightened or loosened in a number of ways, but two preferred ways are shown. In Fig. 16 a left and right hand threaded screw 96 is shown that cooperates with nuts 98 in the elements 80 and 82 to move the upper ends of the elements to and from each other. The left and right hand threaded screw 96 is rigidly attached to, and is rotatable with, handle I00. The other preferred way is shown in Figs. 1'7 and 18. The elements 88 and 82 have arcuate concave recesses I62 formed therein that cooperate with the convex faces I64 on handle I06 .to cause movement of the upper ends of the elements 86 and B2 to and from each other. The use of these string clamps facilitates the rapid stringing of a racket since one short movement of the handle opens the clamp, and another short movement of the han- The yoke 64 has an opening in V dle closes the clamp. Clamp 18 is provided with tooth-like portions I88 that permit the use of the clamp in holding the cross strings after the long strings have been strung. The clamps shown in the drawings are advantageous because of the manner in which they are secured to the guide clips H2. The passing of bar 86 through the openings 84 in stringing clamps I6 and I8, and the fastening of bar 88 to the guide plate clips I I2 by nuts II8 prevents the loss or misplacing of the clamps. Such a construction provides an integrated combination clamp guide and support, that reduces the number of separate parts used in the stringing operation and thereby materially reduces the time required to string rackets. The 5 guide plate clips II2 have a slot H4 in one side thereof that engages the edge of guide plate 32 and maintains the guide plate clips H2 in as sembled relation with guide plate 32. The openings 84 in the string clamps I6 and I8 are slightly larger than the bar 86 and permit easy translation of the clamps along the bar. The size of the openings 84 is such that when the clamps l6 and I8 tend to rotate about an axis perpendicular to the axis of bar 86 under the influence of the tension in the string, the elements 88 and 82 will bind with the bar 86 and prevent movement of the clamps "I6 and I8 relative to the bar 86.

The string-pulling mechanism is pneumatically operated and is substantially self-contained. A tank I28 having an inlet I22, a plug 'I2I, and an outlet I24 is provided to store air under pressure. The inlet I22 is connected to an air valve, not shown, that permits air to be injected into the tank and ordinarily prevents the outlet of air therethrough. The tank I28 is connected to a cylinder I26 by tubing I28, a T- shaped junction I38, either by-pass I32 or valve I34; and tubing I36. A pressure gauge I38 is connected to the system and registers the amount of pressure in tubing I36. A check valve I48 is positioned in by-pass I32 which permits fluid to flow toward the tank I28 but will not permit a flow toward the cylinder I26. A piston I42 seals the cylinder I26 and makes it tight. The piston I42 consists of a metal plug I44 and a flexible cupped disc I46 on the front of the metal plug I44. This cupped disc is maintained against the plug I44 by a spring I48 that is positioned in the end of cylinder I26. The other side of piston I42 has a recess therein that receives a rod I58 which is connected to an L-shaped support I52 carried by reciprocating bar I54. The reciprocating bar I54 is slidably supported by rollers I62 that bridge projections I55 and I58. These projections, like the projections I68 by which the cylinder I26 is supported, are formed integrally with top plate 24. The projections I58 are bridged by rollers I62, a pin I64, and a pin I66. The rollers I62 support reciprocating bar I54, and the pin I66 supports one end of piston I26 and cooperates with supports I68 to hold the cylinder immovable. The pin I64 that bridges projections I58, rotatably supports a yoke I68 in which is rotatably secured a sprocket wheel I18. The sprocket wheel I18 meshes with a chain I12 that is secured at one end to L-shaped support I52 and is secured at its other end to lever I14 which in turn is secured to foot pedal I16. The foot pedal is rotatably secured to studs I18 on base 28 by a pin I88. The foot pedal is also secured to the racketstringing device by a spring I82, A string puller I84 has an opening I86 in the bottom thereof that is only slightly larger than the bar I54.

The engagement between the bar I54- and this opening serves to support the string puller on the bar and permit relative movement between the two. The clearances between the sides of open-' ing I86 and the bar I54 are so small that whenever any torque is impressed on the string puller, the string puller and the bar bind tightly to-' gether and move as a unit. The puller I84 has a snubbing-post I88 and a clamp thereon. The snubbing-post I88 is positioned a short distance irom the clamp and is arranged to receive the string before the string is engaged and held by the clamp. The clamp consists of the main por tion of the string puller I84 and a gripping means I98 which is secured to the main portion by a pin I92. This pin permits the upper end of the gripping means to be moved into and out of engagement with the main portion. The gripping means is guided in its movement by dowels I94 that are secured to the main portion of the string puller I84 and engage holes I96 in the gripping means I98. The upper ends of the main portion and the gripping means tend to separate because of the force exerted by spring I98 which is positioned in recesses I89 in the gripping means and the main body portion of the string puller. The upper ends of the gripping means and the main body portion are moved together against the force of spring I98 by rotation of handle 288. The handle 288 has a convex surface thereon that cooperates with a concave recess in the gripping means of string puller I84 to cause movement of the gripping means relative to the main portion of string puller I84.

If desired, a special form of valve 282 may be placed in the pneumatic pressure system. This valve can be adjusted to permit a flow through it until the pressure on one side thereof reachesa predetermined level whereupon the valve will stop any further flow therethrough. Any form of valve may be used but a preferred form is shown in Fig. 18. A spring 284 forces a gate 286 against the opening 288. The force exerted by the spring 284 is regulated by the rotation of handle 2i 8. The valve is so designed that the pressure impressed on the end of the valve denoted by the numeral 2I2 is added to the force exerted by the spring 284 and is opposed to the pressure exerted on the gate 286 by air in tank I28. pressure at end 282 can be regulated to any desired amount despite the pressure exerted by the air in tank I28.

To string a racket, the operator loosens bolts 44 on one of the racket supports 42 and movesit toward the other racket support 42. One end of the racket head is then laid on the plane surface 46 of one of the supports 42, and the other support is moved away from the first support until the other end of the head of the racket engages the plane surface 46 on the other support. Further movement of the other racket support 42 will be resisted by the engagement of the racket head with the stops 48 on both of the racket supports. The other racket support is then secured tightly to the bar 86 by tightening bolts 44. The racket is secured to the racket supports by tightening the racket clamps. Although many diiferent forms of racket clamps maybe used. the two forms shown in the drawings are preferred. Where the clamp 58 is to be used, the member 52 is inserted in hole 5| in racket support 48 with its bent portion 58 uppermost and wing nut 54 is threaded onto the end thereof. The clamp 58 is then slipped under the By proper manipulation of handle 2H1, the

bent portion 53 of member 52 and the wing nut 54 is tightened. Where clamp 60 is to be used, the member 52 is inserted in the hole 6I therein and wing nut 54 is threaded onto the end thereof. The clamp and the member 52 are then moved into engagement with racket support 42 as shown in Fig. 1 and the wing nut is tightened. These clamps permit the ready insertion and removal of a racket from the racket-stringing device because only a few turns of the wing nut 54 is necessary to tighten or loosen the clamp. An additional clamping means is provided, which is made to prevent crowning of the racket during the stringing operation. Crowning is a bending or warping of the racket frame that is often experienced during the stringing operation. A yoke 64 is placed over the upper portion of the handle of racket 12 and is secured to studs 66 on racket support 42 by a pin 68. The wing bolt that is threaded in yoke 64 is then tightened until it engages and holds the handle of racket 12.

When the racket has been secured to the device, the desired stringing pressure must be selected and impressed on the machine. Pressure is impressed on the machine by any suitable pneumatic device. The cheapest of these devices would be a simple hand pump. Such a device is connected to inlet I22 of tank I20, and air is forced into the tank until the desired pressure is attained. This pressure can readily be ascertained by an examination of pressure gauge I38. A string is then knotted and threaded through oppositely disposed holes on the racket. The racket 12, the racket supports 42, the racket-supporting bar 36, and guide plate 32 are all rotatable around bolt 30; and they are rotated around bolt 30 until the string in the racket is parallel to the axis of translation of reciprocating bar I54. The operator then presses his foot down on pedal I16. This moves the pedal down, pulls on chain I12, pulls on L-shaped support I52 which moves bar I54 and rod I50. The movement of rod I 50 moves piston I42 into cylinder I26 against the pressure in the pressure system. In the preferred form of the device, the cylinder I26, tubing I36, the valves I40, I34, 202, by-pass I32, T-junction I30, tubing I28 and a portion of tank I are filled with oil or other hydraulic fluid. The provision of an hydraulic fluid in a portion of the pneumatic pressure system permits the existence of larger clearances, and thereby decreases the cost of manufacture. It is to be understood, however, that the use of an hydraulic fluid in the pneumatic pressure system is not an essential element of the invention, and air could be used throughout. While the operator holds the pedal I16 down, he moves the string puller I84 along bar I54 until it is close to the racket I12, and then he wraps the string around Snubbing-post I88, passes it through the clamp on the string puller I84, and tightens the clamp by moving handle 200. The provision of snubbing-post I88 in conjunction with a clamp on string puller I84 materially reduces the pressure that must be exerted on the string by the clamp to hold the string securely. The snubbing-post I88 is preferably formed like the frustum of a cone and tends to cause the string to bind against the post whenever the string is placed under tension. This binding eifect also aids in reducing the amount of pressure that must be exerted on the string by the clamp. When the string is secured tothe string puller I84, the operator removes his foot from the pedal I16. The removal of the operator's foot from the pedal and the action of spring I82 in neutralizing the effect of the weight of the pedal, relieves the pressure on the piston I42 that tends to maintain the piston at the right hand end of cylinder I26, and the pressure in the cylinder I26 will force the piston I42, L-shaped support I52, and string pulling bar I 54 to move away from the racket 12. The movement of the bar I54 coop-. erates with the retarding action on the strin puller, of the string in the racket, to cause the string puller I84 and the bar I54 to bind tightly together and move as a unit. The bar and stringpuller will continue to move until the tensionin the string equals the pressure in the cylinder I26 and stops the movement of piston I 42. The string is thus given the proper amount of tension. A string clamp such as'clamp 16 or 18 is then moved into engagement with the string where it passes through the head of the racket and is clamped onto the string. These clamps are mounted on rods 86 that are mounted on guide plate clips I I2, which have a slot machined in one side thereof that is the complement of the edge of the guide plate 32. The guide plate clips II2, bar 86, and stringing clamp 16 or 18 form a unit that is a combination clamp guide and support. The guide plate 32 is made square so the combination clamp guides and supports can be used for both the long and cross strings of a racket. The clamp guides and supports can move back and forth across the plate, and the clamps move back and forth between the clips, thereby giving a universal movement to the clamps. These clamps are tightened and loosened merely by rotation of their handles, and the upper ends thereof'are promptly forced open by springs 92. The connection of a string clamp 16 or 18, a bar 86 and guide plate clips I I2, so that they move as a unit, is quite advantageous. Such an arrangement facilitates the rapid stringing of a racket since it reduces the number of parts to be handled and it obviates the misplacing of any parts during the stringing operation. The guide plate clips II2 are formed with a raised portion to receive the ends of the bar 86. The rest of the guide clips is at a lower level so that the handles of the stringing clamps will not strike the guide clips even when the clamps are positioned close to them. The rate at which the tension i impressed on the strings in the racket can be determined by the setting of valve I34. If it is desired to impress slowly the tension on the strings, the valve is closed until only a limited amount of fluid can pass through the valve in any given period of time. If rapid tensioning is desired, the valve is opened wide. The setting of the valve I34 will not lengthen the time required to move pedal I16 because of a by-pass I32 and check valve I40, which permit rapid flow of fluid back to the tank, but prevent any flow through the bypass in the direction of the cylinder I26.. To continue the stringing of the racket, the operator presses on foot pedal I15, thereby moving the bar and string puller toward the racket. This releases the tension on that part of the string between .the string puller and the racket head. The clamp on the string puller I84 is then loosened by rotation of handle 200, and the string is freed from the string puller and is threaded through two more oppositely disposed holes in the racket. The racket, the racket supports, the racket-supporting bar, the guide plate, the guide plate clips, and the string clamps are then rotated until the string to be tightened is parallel to the axis of translation of the string puller I84. The string is then secured to the string puller, and the pressure on the foot pedal is released. The string clamp which held the first string is then loosened from its engagement with the first string, and is clamped to the second. This procedure is continued until the racket is strung.

Where a number of rackets that are to have different string tensions are to be strung, the valve 202 is very useful. An excessive amount of pressure is impressed on the tank I20, and this can be measured by reference to the gauge I30. While pressure is being impressed on tank I20, the valves I34 and 202 are open. The valves I34 and 202 are then closed tight and the foot pedal is pushed down forcing the fluid through by-pass I32 into tank I20. The pressure on the foot pedal is then released and the-valve I34 is opened. The handle of the valve 202 is then turned until a reading of the desired amount of pressure is registered on the gauge I38. The racket that is to be strung at that pressure is then strung. When another racket that is to have a higher stringing pressure is to be strung, the handle of the valve 202 is turned until the reading on gauge I38 is equal to the desired pressure. If the racket is to be strung at a lower stringing pressure, the valve 202 must be closed, the foot pedal pressed down and released, and then the valve 202 must be opened until the desired pressure can be read on gauge I38. Such a valve obviates the necessity of changing the pressure in tank I20.

Whereas preferred embodiments of the invention have been shown and described, it is obvious to those skilled in the art that various changes in form may be made without altering the scope or efiect of the invention.

It can be seen from the above that the invention provides a substantially self-contained, racket-stringin device and accessories therefor that is operated by pneumatic pressure and gives a uniform tension to each string with a of injury to the strings.

What we claim is:

1. A substantially self-contained, pneumatioperated pressure system for racket-stringing devices comprising a tank adapted to have compressed air, stored in one portion thereof. an inlet to said tank, a cylinder, a piston posi tioned in and slidably engaging said cylinder, :a conduit connecting the tank and the cylinder, a manually operated cutofi valve and a pressure operated cutoff valve in said conduit, a tube bypassing said cutoff valves, 2. check valve :in communication with the by-passing tube which permits flow from the cylinder to the tank but prevents flow from the tank to the cylinder, a pressure gauge indicating the pressure in selected portions of the pressure system, hydraulic liquid in the cylinder, the tube, the conduit, the valves, and the lower portion of the tank, a member to move and to be moved by said piston, afoot pedal, flexible means connecting said movable member and the foot pedal, said movable memher being connected to and; being bodily movable with a string-pullingbar.

.2. A substantially self-contained, pneumatically operated pressure system for racket-stringing devices comprising a tank adapted to have compressed air stored in one portion thereof, an inlet to said tank, a cylinder, a piston positioned in and slidably engaging said cylinder, :a conduit connecting the tank and the cylinder, iamanually operated cutofi valve and a pressure operated cutofi valve in said conduit, a tube by-passing said cutoff valves, 2, check valve in communication with the by-passing tube which permits flow from the cylinder to the tank but prevents flow from the tank to the cylinder, a pressure gauge indicating the pressure in selected portions of the pressure system, hydraulic liquid in the cylinder, the tube, the conduit, the valves, and the lower portion of the tank, a member to move and to be moved by said piston, a foot pedal, a spring connected to said foot pedal adapted to exert a force on the pedal that is equal and opposite to the gravitational effect on the pedal, flexible means connecting said movable member and the foot pedal, said movable member being connected to and being bodily movable With a string-pulling bar.

3. A string puller for racket-stringing devices having a snubbing post and a string clamp thereon, said snubbing post having a plane portion and a second portion that is oblique to the plane portion, said second portion having substantially the shape of a frustum of a cone and being arranged to cooperate with the said plane portion to form a V, said snubbing post being arranged to receive the string before the clamp does, said clamp being opened and closed by movement of ahandle.

4. A string puller for racket-stringing devices having a main body portion, a snubbing post rigidly connected to the main body portion, and a clamping means that is .rotatably connected to the main body portion, a pin to guide the movement of the clamping means to and from the main body portion, resilient means biasing the upper ends of the clamping means and the main body portion to open position, and a handle movable to cause a movement of the upper .end of the clamping means toward the main body portion, said snubbing post being arranged to engage the string before it is engaged and held by the main body portion and the gripping means.

5. Azstring clamp for use with racket-stringing devices comprising two elements each of which has an end that engages the end of the other in a hinge-like manner, an opening through the end of each element to receive a bar on which the elements are supported, threaded portions in the elements, a handle having a left hand and right hand threaded portion that-cooperates with the threaded portions in the elements to force the-ends of the elements toward or away from each other when the handle is rotated, a pin rigidly :secured to one element that slidably engages the other element and guides the movement of the elements to and from each other, and resilient means biasing the free ends of the elements to open position.

6. .A substantially self-contained, pneumatically operated pressure system for racket-stringing devices comprising a tank adapted to have compressed air stored in :one portion thereof, an inlet to said tank, a cylinder, a piston positioned in and slidably engaging said cylinder, a :condm't connecting the tank and the cylinder, a manually operated cutoff valve and a pressure 'operated cutoff valve in said :conduit, a tube lay-passing. said outofi valves, a check valve in communication with the by+passing tube which permits new from the cylinder to the tank but prevents =fiow rirom the tank to the cylinder, a pressure gauge indicating the pressure in selected portions the pressure system, hydraulic liquid the cylinder, thetube, the conduit, the valves,

-compressed air stored in one portion thereof,

an inlet to said tank, a cylinder, a piston positioned in and slidably engaging said cylinder, a conduit connecting the tank and the cylinder, a manually operated cutoff valve in said conduit, a tube by-passing said cutoff valve, a check valve in communication with the by-passing tube which permits flow from the cylinder to the tank but prevents flow from the tank to the cylinder, a pressure gauge indicating'the pressure in selected portions of the pressure system, hydraulic liquid in the cylinder, the tube, the conduit, the valves, and the lower portion of the tank, a member to move and to be moved by said piston, a foot pedal, means connecting said movable member and the foot pedal, said movable member being connected to and being bodily movable with a string-pulling bar. 7

8. A substantially self-contained, pneumatically operated pressure system for racket-stringing devices comprising a tank adapted to have compressed air stored therein, an inlet to said tank, a cylinder, a piston positioned in and slidably engaging said cylinder, a conduit connecting the tank and the cylinder, a manually operated cutoff valve and a pressure operated cutoff valve in said conduit, a tube by-passing said cutofi valves, a check valve in communication with the by-passing tube which permits flow from the cylinder to the tank but prevents flow from the tank to the cylinder, a pressure gauge indicating the pressure in selected portions of the pressure system, a member to move and to be moved by said piston, a foot pedal, flexible means connecting said movable member and the foot pedal, said movable member being connected to and being bodily movable with a string-pulling bar.

9. A substantially self-contained, pneumatically operated pressure system for racket-stringing devices comprising a tank adapted to have compressed air stored therein, an inlet to said tank, a cylinder, a piston positioned in and slidably engaging said cylinder, a conduit connecting the tank and the cylinder, a manually operated cutoif valve in said conduit, a tube bypassing said cutoff valve, a check valve in communication with the by-passing tube which permits flow from the cylinder to the tank but prevents flow from the tank to the cylinder, a pressure gauge indicating the pressure in selected portions of the pressure system, a member to move and to be moved by said piston, a foot pedal, means connecting said movable member and the foot pedal, said movable member being connected to and being bodily movable with a string-pulling bar.

10. A substantially self-contained, pneumatically operated pressure system for racket-stringing devices comprising a tank adapted to have compressed air stored therein, an inlet to said tank, a cylinder, a piston positioned in and slidably engaging said cylinder, a conduit connecting the tank and the cylinder, a manually operated cutofi valve in said conduit, a tube by-passing said cutofi valve, a check valve in communication withthe by-passing tube which permits flow from the cylinder to the tank but prevents flow' from the tank to the cylinder, a member to move and to be moved by said piston, a foot pedal, means connecting said'movable member and the foot pedal, said movable member being connected to and being bodily movable with a string-pulling bar.

11. A substantially self-contained, pneumatically operated pressure system for racket-stringing devices comprising a tank adapted to have compressed air stored in one portion thereof, an inlet to said tank, a cylinder, a piston positioned in and slidably engaging said cylinder, a conduit connecting the tank and the cylinder, a pressure gauge indicating the pressure in selected portions of the pressure system, hydraulic liquid in the cylinder, the tube, the conduit, and the lower portion of the tank, and a member to move and to be oved by said piston.

12. In a racket-stringing device, a substantially square clamp guide plate, and a string clamp combination that is adapted to be slidably secured to the clamp guide plate, said string clamp combination comprising a pair of guide plate clips, a bar connecting the guide plate clips, and a string clamp slidably mounted on the bar, said clamp guide plate and said string clamp combination being adapted to enable the string clamp to hold any of the strings in the racket.

13. In a racket-stringing device, a substantially square clamp guide plate and a string clamp combination adapted to be slidably secured to the clamp guide plate, said string clamp combination comprising a pair of guide plate clips that slidably engage opposite edges of the'clamp guide plate, a bar connecting the guide clips together, and a string clamp slidably mounted on the bar, said string clamp combination being arranged to be alternately supported by the sides or the ends of the clamp guide plate. 7

14. In a substantially self-contained fluid operated racket-stringing device including a racket support and a string puller movable relative thereto, a closed fluid pressure system including a fluid pressure tank, a cylinder, an operative connection between the piston and string puller, and treadle operated means for moving the puller toward the racket support with increased compression of the fluid in the tank upon such movement of the piston in the cylinder, the string puller being movable away from the supp rt in tensioning the string by expansion of the compressed fluid in the tank upon release of the treadle operated means.

15. In a racket-stringing device comprising a frame including a base, a main portion, a top portion, a. rectangular clamp guide plate rotatably supported by said top portion, a string clamp combination comprising a string clamp, a bar on which the clamp is slidably mounted, and a pair of guide clips depending from the ends of said bar and slidably engaging opposite edges of said plate, whereby to hold and guide the cross or long strings of the racket.

16. In a racket-stringing device comprising a frame including a base, a main portion, and a. top portion, a rectangular clamp guide plate rotatably supported by said top portion, a string clamp combination comprising a pair of string clamps, a pair of right angularly disposed bars on each of which one of said clamps is slidably mounted, a pair of guide clips depending from the ends of each of said bars with the clips of the respective bars slidably engaging the right angularly disposed edges of the clamp guide plate.

17. A substantially self-contained fluid operated racket-stringing device, comprising a tank adapted to store compressed fluid therein, a cylinder in communication with the compressed fluid in the tank, a piston positioned in and slidably engaging said cylinder, manually operated means arranged to move said piston against the pressure exerted by the compressed fluid stored in said tank, said piston being arranged to be moved by the pressure of the compressed fluid within the tank whenever the force exerted by the manually operated means is released, a string clamp combination comprising a rotatably mounted rectangular guide plate, guide clips slidably engaging opposite edges of said plate for movement therealong parallel to said edges, a bar bridging said guide clips across said plate, a string clamp adjustably mounted on said bar for movement therealong, and a string puller movable with said piston and mounted beneath said plate for movement in a plane parallel to the axis of said bar and having a snubbing Post and a string clamp thereon.

RUDOLPH A. KAUS'AL. KENNETH C. KAUSAL.

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