US3002644A

US3002644A - Pulling tool

Info

Publication number: US3002644A
Application number: US829803A
Authority: US
Inventors: John L Meyer
Original assignee: Gardner Denver Inc
Current assignee: Gardner Denver Inc
Priority date: 1959-07-27
Filing date: 1959-07-27
Publication date: 1961-10-03
Anticipated expiration: 1978-10-03

Description

J. L. MEYER PULLING TOOL Oct. 3, 1961 3 Sheets-Sheet 1 Filed July 27, 1959 JOHN L. MEYE R INVENTOR.

ATTORNEY.

J. L. MEYER PULLING TOOL Oct. 3, 1961 3 Sheets-Sheet 2 Filed July 27, 1959 Oct. 3, 1961 3 Sheets-Sheet 3 Filed July 27, 1959 l mm \m RM .QQJ .J/\ \k n I r .5 R 5 \h i w a M m w Q I n r2 MU- I H 6Q 3 m mm 3 I 5 5 Ev rm 3 f l. n 1 IN *2 FE G. m2 m2 5 m2 N Bu m 3 on me E .2 5. m2 :2

JOHN L. MEYER INVENTOR.

ATTORNEY.

United States Patent C t'ice 3,ti02,644 PULLHNG TOGL John L. Meyer, Grand Haven, Mich, assignor to Gardner- Denver Company, a corporation of Detaware Filed July 27, 1959, Ser. No. 829,803 13 Claims. (Cl. 218-47) This invention relates to a power operated pulling tool, and more particularly to a pulling tool for setting selfplugging, mechanically-expanding blind rivets.

An efiective and well known form of blind rivet comprises a tubular rivet of relatively ductile material having a head at one end, and a stem extending longitudinally through the tubular rivet having an expander mandrel at one end. This rivet is inserted through aligned holes in a structure to be riveted and may be set by a tool which grips and pulls the stem while holding the rivet head in abutting relation with the structure. The expander mandrel expands the inaccessible end of the rivet against the structure. Continued pulling on the stem, after the rivet is set, results in ruptureof the stem. Since considerable force must be exerted by the tool, first, to move the upsetting mandrel relative to the tubular member and, second, if desired, to rupture the stem, a powerful tool which may be readily handled byan operator is highly desirable.

Blind rivets, as above described, are available in two standard types. In one type, the stem is provided with serrations to facilitate gripping by the jaws of a pulling member. In another type, the stem is provided with a head adapted to be engaged by a pulling member. These two types of blind rivets will hereafter be referred to as serrated type and head type rivets.

An object of this invention is to provide an improved form of pulling tool adapted to install both serrated and head type rivets.

Another object of this invention is to provide a pulling tool having a plurality of interchangeable nose pieces which may be readily attached to, and detached from, the tool for installing'a variety of rivet sizes; each nose piece being adapted to install both serrated and head type rivets of one or more sizes.

A further object of this invention is to provide a pneumatically operated pulling tool which is conveniently operated with one hand and which is rugged, powerful, and of simple construction.

A still further object of this invention is to provide a pulling tool wherein the pulling forces are absorbed within the tool mechanism and wherein none of the pulling forces are absorbed by the tool housing or the motor assembly.

A still further object of this invention is to provide a pneumatically operated pulling tool having a semi-automatic valve and control system whereby the pulling stroke is efiected when a manual valve is actuated and the return stroke is elfected, at any time, when the manual valve is released.

The novel of the features of the invention, as well as additional objects and advantages thereof, will be understood more fully from the following description in connection with the accompanying drawings, in which:

FIGURE 1 is a view of a serrated type blind rivet;

FIGURE 2 is a view of a head type blind rivet;

FIGURE 3 is a side view of a pulling tool embodying the present invention;

FIGURE 4 is a sectional view, taken along the line 44 of FIGURE 3 in the direction of the appended arrows, showing the tool mechanism prior to the start of an operating cycle;

FIGURE 4:: is a transverse sectional view, taken along the line la-41: of FIGURE 4 showing the means for preventing rotation of the nut;

FIGURE 5 is an enlarged sectional view of thenose Patented Oct. 3, 1961 portion of the tool showing the tool mechanism in a re tracted position; a head type rivet being shown in the tool;

FIGURE 6 is a fragmentary sectional view of the handle of the tool showing the manual control valve in position prior to the start of an operating cycle.

Referring now in detail to FIGURE 1 of the drawing, a serrated type blind rivet consists of a tubular rivet 11 of ductile material having a head 13 at one end. A stem 15 extends through the tubular rivet and has an expander mandrel 17 opposite from the rivet head. The stem 15 extends from the rivet head 13 and is provided. with serrations 23 to facilitate gripping by jaws.

Referring to FIGURE 2, ahead type blind rivet comprisesa tubular rivet 11 having a head 13 identical to that previously described. The stem 19 is similar, having an expander mandrel 17. In this type rivet, how-ever, a head 25 is provided at theend of the stem 19 opposite from the expander mandrel to be engaged by a pulling member. The stem 19 is further provided with a constriction 21 of reduced section to define a point where it will rupture. While the rivet heads 13 are shown spherical, they may be flat or of some other configuration.

Referring now to FIGURES 3 through 6, a preferred form of a pulling tool adapted to install the above described'rivets has a gun configuration comprising a rear housing 31 and a forward housing 33, bolted to the rear housing. A handle 35 is integral with the rear housing. The rear housing contains a reversible rotary vane motor 37 and a speed reduction mechanism. The forward housing encloses a ball bearing screw and nut assembly 41 and 42, the screw 41 being rotated by the motor through the reduction mechanism. The rear housing also encloses a control valve assembly 43 and the front housing encloses an adjustablecontrol member 45 associated with the control valve. The handle 35 is provided with. a fitting 47 for an air line and encloses a manual valve assembly 49 for operating a tool. Extending from the forward housing of the'tool is a head 50 which includes a head sleeve 51 enclosing the pulling assembly and an anvil 53. The head sleeve 51 is secured to the nut 42 and the anvil 53 is secured, through a thrust bearing, to the screw 41.

The air motor 37 is a reversible, rotary vane motor of a well known type having a rotor 61 and a plurality of sliding vanes 63. The motor has a single seal point and has air intake chambers (not shown) at either side of the seal point to distribute air to the motor and to provide for reversal of operation. The motor cylinder 64 is provided with air exhaust openings 65 opposite from the seal point from which the exhaust air passes into a chamber 66, then into the forward housing 33 and through exhaust ports 34. A rotor shaft 67 drives spindle 68, connected to the ball bearing lead screw 41, through two planetary gear reduction mechanisms 69 and 71.

The nut 42, mounted in operative relation with the screw 41, has secured to it an anti-rotation member which carries a roller bearing 87. The roller bearing rides in a longitudinally disposed track 88, provided in the forward housing 33, to prevent rotation of the nut 42. An adapter sleeve 89 is threadedly secured to the nut 42 and extends through an opening in the forward end of the forward housing. The opening has a diameter slightly larger than the diameter of the adapter sleeve and acts as a guide for the adapter sleeve.

A thrust bearing 91 is mounted on the forward end of the screw 41. The bearing is provided with a forward facing socket 93 having spring loaded balls. The anvil 53 consists essentially of a tubular member having three longitudinal slots 1&7 extending through the walls of the anvil. The anvil is provided, at its rearward end, with an annular ball retainer groove 109 which is engaged by the balls of the socket 93, in a snap fit, when the head is inserted into the tool. The anvil is provided, at its forward end, with a spherical recess 111 which is adapted to engage a rivet head 13.

The head sleeve 51 surrounds the anvil 53 and is provided, at its rearward end, with external threads for engagement with internal threads at the forward end of the adapter sleeve 89. Hence, the head sleeve is rigidly secured to the nut 42. An internal tapered cam surface 115 is provided adjacent to the forward end of the head sleeve. Three jaws 117 are supported in the head sleeve 51 and in the slots 107 of the anvil. Each jaw 117 is a plate-like member having an inner edge face provided with serrations which are adapted to engage the serrated stem of a serrated type rivet. This face is provided with a notch 121 intermediate its ends adapted to receive and engage the head 25 of a head type rivet. Each jaw is provided with a cam face 123, at its outer edge, which engages the tapered cam surface 115 of the head sleeve. The forward edge of each jaw constitutes a cam face 125 which is adapted for engagement with a mating cam surface 127 defined by the forward end of its respective anvil slot 107. A coil spring 129 is retained between a collar 130, which bears against a rear retainer ring 131 fixed to the head sleeve 51, and a forward retainer ring 133 which bears against the rearward edges of the jaws 117. The jaws are urged forwardly by the spring 129 and ring 133, and are cammed into the position shown in FIGURE 4 by coacting cam surfaces 125 and 127.

Pins 141 are mounted in the collar 130 and extend through the anvil slots 107. An ejector 143 is disposed within the anvil 53 and is biased toward the forward end of the anvil by a coil spring 145, the rearward end of which bears against the inner ends of the pins 141.

The head 50 includes the above described head sleeve 51, the anvil 53, the jaw assembly, and the ejector assembly. The head is readily removable from the tool by unthreading the head sleeve 51 from the adapter sleeve 89 and disengaging the anvil 53 from the socket 93. A set of interchangeable heads may be provided with each tool; each of the heads being designed for use with rivets of a fixed size range.

The rear housing 31 is provided with a longitudinal bore, to accommodate the control valve assembly 43, having five axially spaced annular grooves. A valve bushing 161, of a length sufficient to span the annular grooves, is fitted in the bore. The bushing is provided with a plurality of rings which engage the bore and provide seals between the annular grooves to define, with the grooves,

annular chambers

151, 153, 155, 15 7 and 159. The bushing 161 is provided with a plurality of ports which communicate each of the annular chambers with the interior of the bushing. A control valve 165 is a spool type valve having an outer diameter dimensioned to fit snugly within the valve bushing and having an integral stem 167 which extends forwardly out of the valve assembly bore. The valve 165 is provided with two annular grooves 169 and 171 each of sufiicient width to span two adjacent annular chambers. An end chamber 179 is defined by the rearward end of the valve and the valve bore. A cushion member is provided to limit rearward movement of the valve 165. The forward end of the valve assembly bore is closed by a plug 181 which seals the valve stem 167, limits forward movement of the valve 165, and defines an end chamber 183 at the forward end of the valve around the stem. In the neutral position of the valve, shown in FIGURE 4, no communication is provided between the annular chambers 151 to 159. The valve is movable forwardly and rearwardly from the neutral position so that the valve grooves 169 and 171 span pairs of annular chambers, as will be described.

The annular chambers 153 and 157 communicate (by means of passageways, not shown), respectively, with the two intake chambers (not shown) of the air motor 37. The annular chambers 151 and 159 communicate (by means of passageways, not shown) with the interior of the tool housing to exhaust re-compressed air from the air 4 V motor to atmosphere. The annular chamber 155 and the end chambers 179 and 183 communicate with the manual valve assembly 49 in a manner to be described.

The adjustable control member 45 consists of a threaded rod mounted, for limited reciprocating movement, in the forward housing 33 in axial alignment with the control valve 165. The rearward end of the rod is bored to telescopically receive the valve stem 167 and is connected to the valve stem by means of a pin 201 which passes through a transverse longitudinal slot 203 in the valve stem. This provides a lost motion coupling between the control valve 165 and the control member 45. The forward end of the rod consists of a stem portion of reduced diameter which extends through an opening in the forward housing 33 and includes a slot for manually rotating the rod. A threaded stop collar 205 is fixed at the forward end of the rod and a threaded collar 207 is fixedly mounted adjacent the rearward end of the rod. These collars are engaged by the anti rotation member of the ball screw and nut assembly to reciprocate the control member 45 and control valve 165 in a manner to be described.

Referring now to FIGURE 6, the tool handle 35, which is integral with the rear housing 31, includes a lower chamber 211 which receives air from a supply source through the fitting 47. A stepped bore is provided above the chamber 211 to accommodate the manual valve assembly 49. A passageway 215 extends upwardly from the chamber 211, passing transversely through the stepped bore, and communicates with the annual chamber of the control valve assembly 43. Two passageways 217 and 219 extend upwardly from the stepped bore, on either side of the passageway 215, and communicate, respectively, with the end chambers 183 and 179 of the control valve assembly. A valve bushing 221 is fitted within the stepped bore, spanning the axially spaced

passageways

215, 217 and 219, and is provided with an external annular groove 223 to complete the passageway 215. The bushing 221 is further provided with ports 225 and 227 which communicate the passageways 217 and 219, respectively, with the interior of the bushing. A port 229, positioned axially between the ports 225 and 227, communicates the annular groove 223 with the interior of the bushing.

A cylindrical valve 231 is mounted for reciprocating movement within the bushing 221 and has a forwardly extending stem of reduced diameter. The stem defines a shoulder which is urged against a stop by a spring 237 to define the normal, forward position of the valve 231. The valve 231 is provided with an annular groove 239 of sufficient length to span either the ports 225 and 229, when the valve is in its forward position, or the ports 227 and 229, when the valve is in its rearward position. The valve 231 is further provided with a longitudinal bore 241 extending into the stem and communicating with atmosphere. A fingerpiece 245 is fixed to the forward end of the valve stem for manually operating the valve.

The tool operates in the following manner: In FIG- URES 4 and 6, the tool is shown in the rest condition, which is the condition at the end of an operating cycle. The jaws 117 are camrned into their outermost positions so that a rivet may be received into the head 50. The ejector 143 is held forward by the spring 145. The control valve is in its neutral position and the control member 45 is in its forward position. The manual valve 231 is held in its forward position by the spring237. When the tool is connected to an air supply, air under pressure is provided in the annual chamber 155 of the control valve assembly 43 since this chamber is in continuous communication with the handle chamber 211. The annular chamber 155 is sealed by the control valve 165. Air under pressure, pilot air, is also directed through port 229, annular groove 239, port 225 and passageway 217 to the control valve end chamber 183. The control a valve 165 is prevented from moving rearwardly by the control member 45.

A blind rivet may be inserted in the head 50 ofthe tool or may be inserted into a workpiece W. The tool is then held against the workpiece so that the anvil 53 bears against the head 13 of the rivet to hold the head against the workpiece. The rivet stem is received in the ejector 143 and moves the ejector rearwardly against the force of the spring 145.

The fingerpiece 245 is then depressed to move the valve 231 to its rearward position. filot air is directed through port 229, annular groove 239, port 227 and passageway 219 to the end chamber 179 of the control valve assembly. This air movesthe control valve 165 to its forward position, this movement being permitted through the lost motion coupling with the control member 45. Air in the forward end chamber 183 is exhausted through passageway 217, then through port 225 and the forward end of the manual valve assembly to atmosphere. Chambers 155 and 157 of the control valve assembly are now in communication with each other through the valve groove 171, and air under pressure entering from chamber 155 is directed via chamber 157 to one intake chamber of the air motor 37 to drive the motor in one direction to accomplish the pull stroke of the tool. Since the air motor is reversible, there will be some re-compression of air on the side of the motor which is not the driving side. This air is exhausted from the other intake chamber of the motor to the interior of the tool housing, first through the annular chamber 153 and thence through chamber 151, which chambers are now in communication with each other through the valve groove 169.

During the pull stroke, the nut 42 is drawn rearwardly by the rotating screw 41 and withdraws with it the adapter sleeve 39 and the head sleeve 51. As the head sleeve begins its rearward movement, the jaws 117 are cammed toward each other by the cam surface 115 so that the jaws engage the rivet stem, the notches 121 of the jaws receiving and engaging the head 25 when a head type rivet is being set. With either type of rivet, the stem is gripped by the jaws and the tool then withdraws the stem to cause the expander mandrel 17 to expand or upset the rivet 11 against the blind face of the workpiece. The stem will then rupture, at the constriction 21 if such is provided, and the separated portion of the stem is retained in the jaws. The other portion of the stem remains in, and plugs, the rivet. If the valve 231 is held in its rearward position, the nut 42 will move rearwardly to engage the collar 297 on the control member 45. The control member is then moved rearwardly by the nut 42 and carries with it the control valve 165. When the control valve again reaches its neutral position, the annular chamber 155 is again sealed to stop the motor, and the control member 45 is in its rearward position. FIGURE shows the head assembly at the end of the pull stroke, for example, with a head type rivet in the tool.

The fingerpiece 245 is then released whereby the valve 231 is again urged to its forward position (FIGURE 6) by the spring 237. Pilot air is now directed through port 229, annular groove 23?, port 225, and passageway 217 to the forward end chamber 183 of the control valve assembly. This air moves the control valve 165 to its rearward position wherein the annular chambers 155 and 153 are now in communication with each other through the valve groove 169, and air under pressure entering from chamber .155 is directed via chamber 153 to the other intake chamber of the air motor for reverse drive. This movement of the control valve is again permitted through the lost motion coupling with the control member 45. Air in the chamber 17? is exhausted through passageway 219, port 227, and bore 241 of the manual valve 231. Re-compressed air in the motor is exhausted from the first named intake chamber of the air motor to the interior of the tool housing sequentially through annular chambers 157 and 159, which are now in communication with each other through the valve groove 171.

The return stroke now occurs as the nut 42 is moved forward by the rotating screw 41. Before the nut 42 reaches its forwardmost position, the forward. cam faces of the jaws 117 engage the cam surfaces 127 of the anvil to cam the jaws away from each other and release the severed portion of the stem. The ejector 143 then ejects the severed portion from the tool.

The forward movement of the nut continues until it engages the stop collar 205 of the control member 45. This moves the control member to its forward position, the control member again carrying the control valve to its neutral position wherein the annular chamber is again sealed to stop the motor. This completes the cycle and the tool is again in the condition shown in FIGURE 4.

It will be apparent that, at any time during the pull stroke, the fingerpiece 245 may be released and pilot air will be directed to the end chamber 183 to shift the control valve to its rearward position to commence the return stroke. The shifting of the control valve will shift the control member 45 to its rearward position. Hence, the operator, as soon as the rivet mandrel is ruptured, may release the fingerpiece and need not wait for the complete pull stroke. The length of the pull stroke is readily changed by turning the control member 45 to shift the position of the collar 207.

A feature of the invention is the provision of a tool having removable and interchangeable heads 50 whereby the tool may be used to set a variety of sizes of rivets. A further important feature of the tool is that each of the heads is adapted for setting both serrated and head type rivets.

Another important feature of the invention is the provision for absorbing all of the pulling forces within the tool mechanism. These reaction forces are borne by the ball screw and nut assembly so that none of these forces are transmitted either to the tool housing or to the driving motor assembly. This results in a considerabie advantage since the housing and the motor assembly need not be designed to withstand these forces.

A further feature of the invention isthe provision of a semi-automatic valve actuating meansfor effecting the pull stroke when the manual valve is actuated and'for effecting the return stroke when the valve is released to its original position. With this valve arrangement, the operator has time to remove the tool from the workpiece before permitting the return stroke which ejects the separated portion of the rivet stem. This greatly reduces the possibility of jamming the tool as a result of ejecting the stem before the tool is moved away from the workpiece. Also, the return stroke may be effected at any time by releasing the manual valve. It is not necessary that the tool complete its predetermined pull stroke.

What is claimed is:

l. A pulling tool comprising a housing; a reversible air motor mounted in said housing; a lead screw rotatably driven by said motor; a follower nut driven by said screw; meansin said housing for preventing rotation of said nut; a thrust bearing secured to the forward end. of said lead screw; a head, extending from said housing, comprising an elongated anvil and a sleeve surrounding said anvil; said sleeve being removably secured to said nut and said anvil being removably secured to said thrust bearing; said anvil having an elongated bore and a plurality of longitudinal slots; a plurality of jaws carried by said head in said anvil slots; a tapered cam surface at the forward end of said sleeve; spring means in said sleeve for biasing said jaws forwardly into engagement with said tapered cam surface to move said jaws toward each other into gripping engagement with a member received in said anvil bore; cam surfaces at the forward ends of said anvil slots for urging said jaws away from each other; a reciprocable control valve in said housing for selectively directing air to said motor to drive it in either direction of rotation; said valve having a neutral positionwherein air is sealed off from the motor; a manual valve for directing air to shift said control valve from said neutral. position; a reciprocable control member connected to said control valve through a lost motion coupling; and said control member disposed to be engaged by said nut to shift said control valve to said neutral position.

2. A pulling tool comprising a housing; a reversible air motor mounted in said housing; a screw rotatably driven by said motor; a follower nut driven by said screw; means in said housing for preventing rotation of said nut; a head, extending from said housing, comprising an elongated anvil and a sleeve surrounding said anvil; said anvil having a longitudinal bore and a plurality of longitudinal slots; said sleeve being removably secured to said nut and said anvil being removably and rotatably secured to said screw; a plurality of jaws carried by said head in said anvil slots; said sleeve having a tapered cam surface at its forward end; means in said sleeve for biasing said jaws forwardly into engagement with said tapered cam surface to cam said jaws inwardly into gripping engagement with a member received in said anvil bore; said anvil slots having cam surfaces at their forward ends for camming said jaws away from each other; a reciprocable control valve in said housing for selectively directing air to said motor to drive it in either direction of rotation; manual valve means for actuating said control valve; a reciprocable control member associated with said control valve and disposed for engagement by said nut; said manual valve means actuating said control valve to drive said motor; and said control member actuating said control valve to stop said motor.

3. A pulling tool comprising a housing; a reversible motor mounted in said housing; a screw rotatably driven by said motor; a follower nut driven by said screw; means in said housing for preventing rotation of said nut; a head extending from the forward end of said housing comprising an elongated anvil and a sleeve surrounding said anvil; said anvil having a longitudinal bore and a plurality of longitudinal slots; said sleeve being removably secured to said nut and said anvil being removably secured to said screw; a plurality of jaws carried by said sleeve disposed in said anvil slots; means associated with said sleeve for urging said jaws toward each other into gripping engagement with a member received in said anvil bore; said anvil having means at its forward end for urging said jaws away from each other out of engagement with said member; control means for selectively actuating said motor in either direction of rotation; said motor, in one direction of rotation, moving said sleeve rearwardly with respect to said anvil to engage said jaws with said member and to pull said member with respect to said anvil; and said motor, in the other direction of rotation, moving said sleeve forwardly with respect to said anvil torelease said member from said jaws.

4. A pulling tool comprising a housing; a reversible motor mounted in said housing; an assembly comprising lead screw and nut elements, one of said elements being rotatably driven by said motor and the other of said elements being driven axially by said one element; a head extending from the forward end of said housing comprising an elongated anvil and a sleeve surrounding said anvil; said anvil having a longitudinal bore and a plurality of longitudinal slots; said sleeve being removably secured to one of said elements and said anvil being removably secured to the other of said elements; a plurality of jaws carried by said sleeve disposed in said anvil slots; means associated with said sleeve for urging said jaws .toward each other into gripping engagement with a member received in said anvil bore; said anvil having means .at its forward end for urging said jaws away from each other out of engagement with said member; control means for selectively actuating said motor in either direction of rotation; said motor, in one direction of rotation, moving said sleeve rearwardly with respect to said anvil to engage said jaws with said member and to pull said member with respect to said anvil; and said motor, in the other direction of rotation, moving said sleeve forwardly with respect to said anvil to release said member from said jaws.

5. A pulling tool comprising a housing; a reversible motor mounted in said housing; an element driven reciprocably by said motor; an axially fixed element; a head extending from the forward end of said housing comprising an elongated anvil and a sleeve surrounding said anvil; said anvil having a longitudinal bore and a plurality of longitudinal slots; said sleeve being removably secured to one of said elements and said anvil being removably secured to the other of said elements; a plurality of jaws carried by said sleeve disposed in said anvil slots; means associated with said sleeve for urging said jaws toward each other into gripping engagement with a member received in said anvil bore; said anvil having means at its forward end for urging said jaws away from each other out of engagement with said member; control means for selectively actuating said motor in either direction; said motor, in one direction, moving said sleeve rearwardly with respect to said anvil to engage said jaws with said member and to pull said member with respect to said anvil; and said motor, in the other direction, moving said sleeve forwardly with respect to said anvil to release said member from said jaws.

6. In a pulling tool the combination comprising a housing; a reversible motor mounted in said housing; a screw rotatably driven by said motor; a follower nut driven by said screw; means in said housing for preventing rotation of said nut; a head extending from the forward end of said housing comprising an elongated anvil and a sleeve surrounding said anvil; said anvil having a longitudinal bore and a plurality of longitudinal slots; said sleeve being removably secured to said nut and said anvil being removably secured to said screw; a plurality of jaws carried by said sleeve in said anvil slots for gripping a member received in said anvil bore; means for operating said motor in one direction of rotation to move said sleeve rearwardly with respect to said anvil and with respect to said housing to pull said member with respect to said anvil; and the reaction forces due to said pulling etfort being absorbed within the screw and follower nut mechanism of the tool apart from said tool housing.

7. In a pulling tool: a housing; a reversible air motor; a lead screw rotatably driven by said motor; a follower nut driven axially by said lead screw and connected to a pulling member; a valve bore in said housing having individual ports communicating with two intake chambers of said motor and with a source of air under pressure; an axially shiftable spool valve disposed in said bore for selectively closing said source port and communicating said source port with said motor intake ports; said valve defining, with said valve bore, end chambers at either end thereof; a shiftable control member connected to said spool valve by means of a lost motion coupling; said control member being disposed to be engaged by said nut to shift said member; manual valve means for directing air selectively to said end chambers to shift said spool valve in either direction from a neutral position to drive said motor; said shifting of said spool valve occurring without accompanying shifting of said control member due to said lost motion coupling; and said control mem her being shifted by said nut, with accompanying shifting of said spool valve, to return said spool valve to its neutral position to stop the drive of said motor.

8. In a pulling tool having a reversible air motor, a screw rotatably driven by said motor, and a follower nutdriven axially by said screw and connected to a pulling member: the combination comprising an axially shiftable control valve for selectively directing air to said motor to drive the same in either direction; said valve having a neutral position wherein air is sealed off from the motor; a shiftable control member connected to said control valve by means of a lost motion coupling; means on said control member disposed to be engaged by said nut to shift said member; a manually operable valve for directing air to shift said control valve from said neutral position in either direction to drive said motor; said shifting of said control valve occurring without accompanying shifting of said control member due to said lost motion coupling; and said control memher being shifted by said nut, with accompanying shifting of said control valve, to return said control valve to its neutral position to stop the drive of the motor.

9. In a pulling tool having a reversible air motor, a screw rotatably driven by said motor, and a follower nut driven axially by said screw and connected to a pulling member: the combination comprising a valve assembly including a valve bore and an axially shiftable control valve; means defining individual ports communicating said valve bore with two intake chambers of said motor and with a source of air under pressure; said control valve and said valve bore defining chambers at either end of said control valve; said control valve having a neutral position in said bore wherein said source port is sealed and having means for communicating said source port with said motor intake ports when shifted from said neutral position; a shiftable control member connected to said control valve by means of a lost motion coupling; adjustable means on said control member disposed to be engaged by said nut; a manually operable valve communicating said end chambers with a source of air under pressure; said manual valve being operable to selectively direct air to said end chambers to shift said control valve from said neutral position to drive said motor in either direction; said shifting of said control valve occurring without accompanying shifting of said control member due to said lost motion coupling; and said control member being shifted by said nut, with accompanying shifting of said control valve, to return said control valve to its neutral position to stop the drive of the motor.

10. For use with a pulling tool having a reversible motor, a screw rotatably driven by said motor, a thrust bearing mounted at the forward end of said screw, and a follower nut driven axially by said screw: a head comprising an elongated anvil and a sleeve surrounding said anvil; said anvil having a longitudinal bore and a plurality of longitudinal slots; means at the rearward end of said anvil for detachably connecting the same to said thrust bearing in axial alignment with said screw; means at the rearward end of said sleeve for detachably connecting the same to said nut; said sleeve having a tapered cam surface adjacent its forward end; a plurality of jaws carried by said head, confined in said anvil slots within said sleeve; spring means in said sleeve for biasing said jaws forwardly into engagement with said tapered cam surface to cam said jaws toward each other to engage a member received in said anvil bore; said anvil slots having cam surfaces at the forward ends thereof for camming said jaws away from each other; an ejector disposed for longitudinal movement witin said anvil bore; spring means carried by said sleeve for biasing said ejector in a forward direction to engage a member received in said anvil bore; said jaws being cammed toward each other to engage said member when said sleeve is moved rearwardly with respect to said anvil; and said jaws being cammed away from each other to release said member when said sleeve is moved forwardly to engage said jaws with said anvil cam surfaces.

11. For use with a pulling tool having a reversible motor and a member driven reciprocably by said motor: a head comprising an elongated anvil and a sleeve surrounding said anvil; said anvil having a longitudinal bore and a plurality of longitudinal slots; means at the rearward end of said anvil for detachably connecting the same to said tool; means at the rearward end of said sleeve for detachably connecting the same to said motor driven member; said sleeve having a cam surface adjacent its forward end; a plurality of jaws carried by said head, confined in said anvil slots within said sleeve; means in said sleeve for biasing said jaws forwardly into engagement with said cam surface to cam said jaws toward each other to engage a member received in said anvil bore; said anvil slots having cam surfaces at the forward ends thereof for camming said jaws away from each other; an ejector disposed for longitudinal movement within said anvil bore; means carried by said sleeve for biasing said ejector member in a forward direction to engage a member received in said anvil bore; said jaws being cammed toward each other to engage said member when said sleeve is moved rearwardly with respect to said anvil; and said jaws being cammed away from each other to release said member when said sleeve is moved forwardly to engage said jaws with said anvil cam surfaces.

12. For use with a pulling tool having a reversible motor and a member driven reciprocably by said motor: a head comprising an elongated anvil and a sleeve sur rounding said anvil; said anvil having a longitudinal bore and a plurality of longitudinal slots; means at the rearward end of said anvil for detachably connecting the same to said tool; means at the rearward end of said sleeve for detachably connecting the same to said motor driven member; said sleeve having cam means adjacent its forward end; a plurality of jaws carried by said head, confined in said anvil slots within said sleeve; means in said sleeve for biasing said jaws forwardly into engagement with said cam means to cam said jaws toward each other to engage a member received in said anvil bore; said anvil slots having cam surfaces at the forward end thereof for camming said jaws away from each other; said jaws being cammed toward each other to engage said member when said sleeve is moved rearwardly with respect to said anvil; and said jaws being cammed away from each other to release said member when said sleeve is moved forwardly to engage said jaws with said anvil cam surfaces.

13. For use with a pulling tool having a reversible motor, an element driven reciprocably by said motor, and an axially fixed element: a head comprising an elongated anvil and a sleeve surrounding said anvil; said anvil having a longitudinal bore and a plurality of longitudinal slots; means at the rearward end of said anvil for detachably connecting the same to one of said elements; means at the rearward end of said sleeve for detachably connecting the same to the other of said elements; said sleeve having cam means adjacent its forward end; a plurality of jaws carried by said head, confined in said anvil slots within said sleeve; means in said sleeve for biasing said jaws forwardly into engagement with said cam means to cam said jaws toward each other to engage a member received in said anvil bore; said anvil slots having cam surfaces at the forward end thereof for camming said jaws away from each other; said jaws being cammed toward each other to engage said member when said sleeve is moved rearwardly with respect to said anvil; and said jaws being cammed away from each other to release said member when said sleeve is moved forwardly, with respect to said anvil, to engage said jaws with said anvil cam surfaces.

References Cited in the file of this patent UNITED STATES PATENTS 2,353,451 Fischer July 11, 1944 2,423,957 Amtsberg July 15, 1947 2,525,626 Stouffer et a1. Oct. 10, 1950 2,583,733 Fischer et al. Ian. 29, 1952 2,794,567 Stau et a1. June 4, 1957