US2616323A - Power actuated wrench - Google Patents

Description

Nov. 4, 1952 L. A. LEIFER POWER ACTUATED WRENCH 5 Sheets-Sneet 1 Filed Dec. 1'7, 1948 FIG. 1.

INVENTOZQ. Lorenz All/safer BY m z .i/Mi

ATTORNEYS.

Nov. 4, 1952 A. LEIFER POWER ACTUATED WRENCH 5 Sheets-Sneet 2 Filed Dec. 17, 19

uvmvrog Lorenz Alegfer BY MM 2 x/ad/z AT TORNEYS.

L. A. LEIFER POWER ACTUATED WRENCH Nov. 4, 1952 3 Sheets-Sheet 3 Filed Dec. 17, 1948 INVENTQR. v Lorenz ALezfez' afia $1M ATTORNEYS.

Patented Nov. 4, 1952 POWER ACTUATED WRENCH Lorenz Albert Leifer, Madison, Wis., assignor to Gisholt Machine Company, Madison, Wis., a corporation of Wisconsin Application December 17, 1948, Serial No. 65,842

14 Claims.

1 This invention relates to a power wrench suitable for operating a multiple jaw scroll chuck or the like.

An object of the invention is to provide a power actuated wrench for opera-ting a chuck or the like to effect initial rapid adjustment with light forces, and subsequent predetermined power actuation of the wrench.

Another object of the invention is to provide a power wrench for operating a chuck or the like in which the workpiece is rapidly centered in the chuck.

Another object of the invention is to provide a power wrench for operating a chuck or the like which rapidly centers the work in the chuck and then firmly grips the workpiece.

Another object is to provide a power wrench for operating a chuck or the like in which the applied torque may be selectively controlled so that distortion of a thin walled workpiece within the chuck does not occur.

A further object is to provide a power wrench for operating a chuck or the like which embodies a safety interlock to prevent turning of the spindle under power when the wrench is engaged with the chuck.

Another object is to provide a power Wrench in which the torque applied to the wrench may be selectively varied over a wide range.

Another object is to provide a power wrench having two steps of torque application, the first being an adjusting step and the second being a final torque force step, and in which the two steps are carried out in automatic correlation.

Another object is to provide a multiple step power wrench in which the torque force applied in each step may be independently adjusted.

Another object is to provide a multiple step power wrench in which the activating forces for the first step remain effective throughout the actuation of the subsequent steps to provide a final cumulative torque for the wrench.

Other objects and advantages of the invention will appear hereinafter.

The invention employs a worm gear drive for the wrench head and utilizes the worm as a rack in applying the final torque forces to the wrench head. The worm is rotated by a motor, preferably either electric or fluid pressure operated, which is capable of applying the necessary torque forces to the wrench head for adjustment of the chuck and for light chucking forces upon the workpiece, and which stalls when it reaches the limit of a chucking operation. The

worm is reciprocated by a motor, preferably either of the electric solenoid type or fluid pressure cylinder and piston type, to operate the same as a rack after stalling of the rotary motor to thereby apply the final torque forces to the wrench head and effect the desired final adjustment of the chuck to grip the workpiece.

The invention is illustrated in the accompanying drawing in which:

Figure 1 is a front elevational View of the power wrench of the invention;

Fig. 2 is a plan view of the wrench;

Fig. 3 is a transverse section taken on line 3-3 of Fig. 1 axially of the wrench shaft;

Fig. 4 is an enlarged sectional view taken on line 44 of Fig. 2 showing the control valve;

Fig. 5 is a sectional view taken on line 55 of Fig. 2 at right angles to Fig. 4 and showing the operating cam control;

Fig. 6 is a detail sectional View taken on line 5-6 of Fig. 2 showing the relief valves;

Fig. '7 is a schematic view of the hydraulic system of the invention; and

Fig. 8 is a schematic view of the power wrench of the invention in engagement with a socket in a lathe chuck with the jaws of the chuck gripping a workpiece, and with the power to the spindle motor interrupted by a micro-switch.

The power wrench illustrated has a body i which may be made up of any number of parts suitable for containing the mechanism hereinafter described.

The wrench head 2, illustrated as a hexagonal member, is carried at the end of a rotary shaft 3 extending axially through a worm gear 4 with which it rotates in body I.

The worm gear 4 is driven by means of a worm 5 meshing therewith and mounted for rotation and for limited axial movement in body I.

Worm 5 is rotated by means of a suitable r0- tary motor 6 which has its shaft 7 coupled to one end of the worm by means of the spline coupling 8 to provide for axial movement of worm 5 relative to the motor.

Worm 5 is moved axially by means of a suitable reciprocating motor 9 at the end opposite motor 6. Axial movement of worm 5 serves to utilize the same action as a rack in turning worm gear 4 and wrench head 2.

Motors 6 and 9 may be either electric or fluid operated. They should have the characteristic of stalling at the final actuating position of maximum torque on the wrench head 2.

Motors 6 and 9 should be operated in correlation so that rotary motor .6 has a relatively high speed with a low torque for wrench head 2,

and motor 9 applies a limited predetermined generally high torque force to the head. The motors are operated in sequence whereby rotary motor 6 drives the wrench head 2 rapidly toward final position and until it stalls, and thereafter motor 9 moves the worm 5 as a rack and drives the wrench head 2 to final tightening position.

During the forward operation of motor 9 the motor 6 remains active in holding worm 5 against yielding in reverse rotation. In the event motor 9 reaches the end of its stroke before it reaches the stalling position determinedb'y the wrench torque desired, the motor 9 is merely reversed to move worm 5 in the opposite direction while motor 6 rotates the worm forwardly to take up the gain in tightness obtained by initial operation of motor 9'. "Th'e'nar'iother for ward stroke of motor 9 will generally accomplish the desired result. As many strokes of the motor m y. be. p d. 9 .5. ma b re ire to 6. 1 the final stalling position.- 7 V v When wrench head2 is to be operated in reverse to loosen a chuckorthe like, the motor 9 st p era n, a rev rs iir i n. o brea loose the tightness involved andma bereciprocated as many times as necessaryuntilmotor 6 takes hold and rotates worm 5 in the reverse direction, In this sense, both-motors 6 and 9 should be reversible. r I H The power wrenchillustrated herein is opere y, m s. uid.n s. u e M t r a reversible rotary vane type motor either with a relief valve in both lines or having maximum tbrque Output o he flu d fsv temu l whi h coincides with the desiredstalling torque to de- Referring to Fi g. 7 which inustratesa preferred fluid actuating circuit, employing a liquid, the sump l0 supplies liquid tOpumplI. Both sump l0 and pump II may be located outside the body 'of thewrench, and areconnected thereto by suitable piping or pressure hose conduits, the conduit [2 serving to transmit pressure fluid from pump I! to avalve [3 in wrenchbody I, and the conduit l4 serving to drain fluid from valve I3 to sump Ill. 7

'The main control valve l3 in wrench body I is of the spool type having a cylinder constituting the valvebodyfand an operating spool or plunger'lfi disposed to be reciprocated therein.

The valve plunger I6, is operated by means of a manual lever I! through suitable gearing l8 and a rack l9 on the stem of the spool. The lever ll has a centralneutral position in which it is bers 22. The drain conduit 14 connects with one,

end 22 of the cylinder and an axial passage 4 23 through the plunger It connects the two end chambers 22.

Two passages 24 and 25, respectively, extend from valve l3 to motor 6; and, depending upon the direction of operation of the motor, either passage may conduct power fluid to the motor from conduit, I2. through valve, l-3, while the other passage conducts the motor exhaust back through valve [3 to drain conduit l4.

Two passages 26 and 21, respectively, extend from valve [3 to opposite ends of the cylinder 23 of motor 9; and, depending upon the direction of operation of the motor, either passage may conduct power fluid to the motor from conduit I2through, valve I3, while the other passage conducts the motor exhaust back through valve l"3"to drain conduit I4.

In normal position of valve plunger I6 both passages 24 and 25 are ported to the fluid supply chamber 2!, and both passages 26 and 2lare ported to the exhaustchambers 22 atopp'osite ends'of the valve. In'this neutral position neither motor 6 nor motor 9 operates.

Forward operationof motor 6 is obtained by movement of 'control'leve'r I! to the F1 position which effects a downward movement of valve plunger 16 to a position where upper flange '20 passes the port for passage 25, thereby connecting the "paSsa'geQto upper fiira'in Chamber '22 and providing for forward rotation of motor .6. Upon stalling of motor "6, as previously described, the operator moves control leverfll "t'o position F2 which e'flec'ts a furtherdownward movement'o'f valve plunger [5 to a position where lower flange 2ll"pa'sse's' the port for passage 26, therebyconne'cting'the passage. to the central supply chamber which supplies power fluid to theupper "end of cylinder, 28 to drive piston 29fof motorf9 downwardly.

' Upon stalling of motor "9, where a liquid power fluid iswused, the liquid being pumped by pump l'l is allowed to bleed back into sump l0 through a branch line 30 and adjustable relief valve 3| emptying into drain line 32 which extends to the sump.

When it is desired to, move piston 29 upwardly fora fseco'nd tightenihg, stroke, lever' l 1 'is' merely moved to the F1 position, whereupon motor '6 will rotate to move worm 5 upwardly and to push piston 29 upwardly. Thereafter, movement of lever ll to the F2 position will effect a second downward stroke of piston 29 and the worm rack 5. 7 v

After completion of the tightening operation with the wrench head2, lever 11 should be returned toQneutral position so that the head may be released and disconnected from the chuck '33 which is operated byit.

When it is desired to release the workpiece 34 from chuck 33, wrench head 2- is brought into engagement with the chuck actuating member 35 andlever ll is moved to the reverse position R2. In this position for le'ver 'I l the 'valveplunger I6 is moved upwardly until the passage 27 is connected to fluid supply chamber 2| and both passages 24 and 26 are 'co'nnectedto the lower drain chamber22, whereby passagezl conducts power fluidto the lower end of cylinder 28 to forcejpi'sto'n '29 and fworm-"rack'5 upwardly, and passage 25 conducts Dower fluid to motor Bto apply torque of the chuck by motor 6, the piston 29 may be moved downwardly preparatory to another stroke. For this purpose lever I 1 should be moved to position R1, releasing the underside of piston 2-9 of supporting pressure, and motor 6 will then pull the piston down by the threading action of worm 5 in the teeth of worm gear 4. Then lever I1 is moved to position R2 to repeat the upward stroke of the piston 29. As many strokes of piston 29 may be employed as is necessary to release the chuck resistance to a value where motor 6 can open the chuck by rotating worm 5.

The stalling of motor 9 when the piston 29 reaches the upper limit of its stroke effects operation of an adjustable relief valve 36 in a branch line 31 between passage 21 and drain line 32 to provide for pressure relief.

For the operation described relief valve 36 should be set to open only under maximum high pressure conditions since it is desired to have an excess of operating force upon piston 29 to break the chuck 33 loose from its tight grip upon the workpiece 34.

The wrench may be employed for operating scroll chuck 33 to internally grip a hollow work piece, in which event the operation of lever I1 and the resulting directional operation of motors 6 and 9 for chucking and unchucking are just the opposite to the operations described above.

The relative adjustment for relief valves 3I and I 36 will depend upon the chucking operation. In

the construction shown, for external chucking, the relief valve 3| may be set to open at any value of fluid pressure for obtaining the desired chucking pressures upon the workpiece, and relief valve 36 is set to open at the highest possible fluid pressure available for the purpose. For internal chucking valve 3I should be set high and valve 36 should be set to determine the chucking pressure desired.

The pitch of worm 5 may provide a locking angle between the worm teeth and the teeth of worm gear 4 so that substantially no back threading results when utilizing the worm as a rack. However, such a pitch for the worm may make the actuation of chuck 33 by motor 6 too slow.

It is possible to make the pitch of worm 5 somewhat steeper than a locking angle and to utilize the torque of motor 6 to prevent back threading when the worm becomes a rack, as described above. For this purpose motor 6 must be operated under either a stall or a predetermined slippage condition at a torque output value sufficient to prevent slippage and the resulting undesirable back threading of worm 5.

Motor 6 can be stalled below its maximum torque output through the action of an adjustable pressure relief valve 42 disposed in the main supply conduit I2 of the fluid system. Valve 42 communicates with sump I0 through a drain line. In the F1 position of manual lever I'I, fluid is supplied by conduit I2 only to passage 24 leading to motor 6. A predetermined setting of valve 42 will limit the fluid pressure in passages I2 and 24 to cause stalling of motor 6 at a desired torque output.

The torque output value for motor 6 in either direction during operation of motor 9 can be adjusted and predetermined by providing a pair of adjustable pressure relief check valves 38 and 39 associated with either end of cylinder 28 and the corresponding passage 26 or 21, as the case may be.

In the illustration of Fig. '7 relief valve 38 is in passage 26 and operates to admit fluid to cylinder 28 only upon a predetermined building up of pressure in passage 26, thereby maintaining the predetermined fluid pressure to establish the desired torque output for motor 6. Relief valve 39 is disposed in a passage 40 which by-passes valve 38 and extends from cylinder 28 to the passage 26. Valve 39 faces the opposite direction from valve 38 and acts as a check valve against passage of fluid from passage 26 into cylinder 28. In this way valve 38 alone serves to adjustably control the torque of motor 6 when motor 9 moves worm 5 downwardly as a rack.

When the operations are reversed, and it is desired to move the worm 5 upwardly as a rack, the torque of motor 6 is maintained by the adjustable relief valve 39 which controls the escape of fluid from the upper end of cylinder 28 and thereby the necessary pressure in passage 21 to raise piston 2-9. At this time valve 38 serves as a check valve.

If desired, a pressure gauge 4I may be provided in line I2 to indicate to the operator the several stages of motor operation. Also the pressure relief valve 42 disposed in line I2 controls maximum pressure in the system and provides for discharge of liquid to the sump from pump II when motor 6 is stalled.

The wrench is particularly adapted for operating scroll chucks of lathes as described above and as illustrated in Fig. 8. For this purpose the invention provides a safety interlock to prevent rotation of the lathe spindle and chuck during operation of the wrench, and provides for engagement and disengagement of the wrench head 2 with the actuating socket 35 for the chuck.

In the construction illustrated shaft 3 is splined for axial movement relative to worm gear 4 and is carried thereby. Worm gear 4 has end trunnions 43 rotatably mounted in suitable bearings 44 in body I.

Axial movement of shaft 3 is controlled by means of a piston 45 operating in a pressure cylinder 46 at the inner end of the shaft. Piston 45 is non-rotary and a coupling 41 between the piston and shaft 3 embodies a suitable bearing and at the same time secures the two against axial separation.

A spring 48 biases piston 45 in a direction to move shaft 3 inwardly to the inoperative position where wrench head 2 becomes disengaged from socket 35 and recedes into the outer trunnion of worm gear 4.

Fluid pressure applied to the side of piston 45 opposite spring 48 serves to move the piston against the spring and to force shaft 3 outwardly thereby causing wrench head 2 to enter socket 35. For this purpose, conduit passage 49 extends from conduit I2 to the end of cylinder 46 to supply power fluid to the latter.

A two-way valve 59 is connected in passage 49 for the purpose of alternately connecting cylinder 46 to fluid supply conduit I2 and to drain conduit 5| leading to sump I6.

Valve 50 is controlled in correlation to the op eration of the wrench, by means of a rotary cam 52 which is operated by lever I1, and which presses against a spring biased valve plunger 53.

Plunger 53 is maintained normally during inaction of the wrench, by spring 54 in a position blocking passage of fluid through conduit 49 and connecting cylinder 46 to drain conduit 5|.

During operation of the wrench, as when lever I1 is moved to any one of the positions F1, F2, R1, and R2, cam 52 moves valve plunger 53 against spring 54 and to a position disconnecting drain 7 cdnduit 5| irom conduit 4'9- and opening the 'lat- 'ter to supply pressure fluid from-conduit 12 to cylinder 46.

The normalposition for valve plunger 53 tends to .lock'cam 52 against turning and thereby to maintain lever I! in neutral :position.

The interlock between the wrench and the lathespindle'55 is provided by a cut-out switch '56 in the control circuit for the.spindle=motor"51.

The switch 56 is normally closed by reason :of

The invention providesa power-:wrench which capable of rapid operation for high ratio-scroll chucks, and which can besadjustedzto providezior a wide range of substantially predetermined chucking forces. Either light gauge stock'or-solid bar stock may be chucked ibythe use aof. the

wrench.

Variousembodimehtsof the. invention may be employed withinrthe scope of-the accompanying claims. 7 V The invention is claimed as follows:

LEA power actuated Wrench comprising a wrench head supported-forrotation, a worm; gear drive for said head disposed to rotate *thesame,

a rotarymotor'connected-to saiddrive to rotate .the driveworm thereof at ,high'speed underlow torque forces on the wrenchhead and having a stall zpoint when a substantially {predetermined 'to'rque forceis reached, a reciprocating-motor disposed to move said drive worm longitudinally as a; gear rack to apply additionaltorqueeiorces -torsai'd wrench head, iandsmeans ;to-;actuate-- sa id reciprocating motor uponstalling of; said rotary motor.

'2.A power actuated wrench *comprising a wrench; head supported; for rotation; a-worm: gear drive for said head disposed to rotatethesame, :al'rot'orymotor connected to said-driveto rotate the drive worm thereoiathighxspeed under 'low torque'forceson thewrench'head; and hav- 0 --ing: a.stall point'when a substantiallypredetermined torque force is reached,ereciprocating motor disposed to movesaid drive-wormalongitudinally'as a gear rack to apply additional torque forces to said'wrench head, means to actuatesaid reciprocating motor upon stalling of-said: rotary motor, and means disposed'to operate-said-rotary motor and to effect a: continuance of torqueby said motor after stalling andduring thetpower operation of said reciprocating' motor; tdprevent threading action of saiddrive :wor-zn whereby: the

worm simulates a'gearrackin action. 7

3. A power actuated wrench :comprising a wrench head supported for rotation; a worm gear drive for' said"headvdisposed' to rotate the same, a rotary motor connectedztocsaicl. drive", to: rotate the drive worm thereof at high speed underlow torque forces on the'wrenchhead'and having a stailpoint when a substantially predetermined torque force is reached, aEreciprocating-motor disposed to move said drive worm--longitudinallyzas ax-gear rack to. apply additional torque forces to said wrench: head: means to: actuate said; reciprocating niotor uponsstallingeof said -rotary-"-motor,

dandmeans-:disposeda temperate isaidirotary: motor:

f8 and to e'fiect a continuance ;of torque by said motor after stalling and during thepower operation of said reciprocating motor to prevent threading action of'said drive worm whereby the worm simulates agear rack in action, said means beingadditionally eiTective to provide a threading action for the drive worm upon the nonpower stroke of said reciprocating motor whereby several successive rack motions may be employed to applyhigh torqueto said wrenchhead.

.4. A power actuated wrench comprising a wrench head supported ,for rotation, a Worm gear drive for said head disposed to rotate :the same, a reversible'rotary fluid operated-motor connected .to the drive-to rotate the same worm for said worm gear drive at high speed under low torque forces on the wrench head and having a stall point when a substantially predetermined torque :force is reached, a 'double acting reciprocating piston motor connected :to said drive worm to -move the same longitudinally as a gearrack to apply additional torque forces to said wrench head, means to initiate actuation of said reciproeating motor to advance saidworm upon stalling of said rotary motor, and means to supply power fluid to said motors to operate the same in correlation.

5. A power actuated wrench comprising a wrench head supported for rotation, a wormgear drive for said head disposed to rotate the-same, a reversible rotary fluid operated motor connected to the drive worm for saidworm gear drive-to rotate the same at highspeed under low torque forces on the wrench head and having a stall point when a substantially;predeterminedtorque 'force is reached, a double acting reciprocating piston motor connected to said drive worm to move the same longitudinally as a gear rack to :apply additional torque forces to said wrench head, means to initiate actuation of said reciproeating motor toadvance said worm upon stalling of-"saidrotary motor, and means tosupply power fluidto said motors tooperate'the same incorrelation, said last named -means including a .manually operated control valve adapted to selectively distribute power'fluid either to said rotary'motor alone to operate the same in-either direction orto both said motorssimultaneously to operate the same in a mutually correlated direction for applying high torque-to said wrench head.

6. A power actuated wrench comprising a wrench head supported for rotation, a worm gear :dliVB for said; head disposed'to rotatethe same, .a

, point when 1 a substantially predetermined torque =force-is reached, a doubleactingreciprocating hydraulic cylinder andpistonmotor connected to saiddriveworm to move the same longitudinally as-agear rack to apply additional torque'forces tosaid wrench head upon stalling of said rotary 'and a master control valveconnectedbetween *sai-d puinpand said motors andhaving -an'operable valve membermovable to selected positions for delivering power-liquid from-saidpump toeitherside of the rotary motor and to either end 'ZOf the reciprocating :motorand for; returning liquid from said motors to said reservointhe {delivery ports in said'valve' being disposed inrewlation to;said-movabla valve member to effect op- 9 eration of said rotary motor in one direction when said member is moved in one direction from neutral and in the opposite direction when said member is moved in the opposite direction from neutral and to effect cooperative movement of said reciprocating motor while maintaining torque on said rotary motor when said member is moved a second increment in the selected direction from neutral.

7. A power actuated wrench comprising a Wrench head supported for rotation, a worm gear drive for said head disposed to rotate the same, a reversible rotary hydraulic motor connected to the drive worm for said worm gear drive to rotate the same at high speed under low torque forces on the wrench head and having a stall point when a substantially predetermined torque force is reached, a double acting reciprocating hydraulic cylinder and piston motor connected to said drive worm to move the same longitudinally as a gear rack to apply additional torque forces to said wrench head upon stalling of said rotary motor, a closed circuit hydraulic power system for said motors comprisin a liquid reservoir, a pump drawing liquid from said reservoir, and a master control valve connected between said pump and said motors and having an operable valve member movable to selected positions away from a neutral closed position for delivering power liquid from said pump to either side of the rotary motor and to either end of the reciprocating motor and for returning liquid from said motors to said reservoir, the delivery ports in said valve being disposed in relation to said movable valve member to effect operation of said rotary motor in one direction when said member is moved in one direction from neutral and in the opposite direction when said member is moved in the opposite direction from neutral and to effect cooperative movement of said reciprocating motor while maintaining torque on said rotary motor when said member is moved a second increment in the selected direction from neutral, and an adjustable relief valve connected between said control valve and each end of said reciprocating motor draining power liquid to the reservoir, whereby the maximum power actuation of said reciprocating motor may be adjusted to provide a substantially predetermined torque actuation of said wrench head when utilizing the drive worm as a gear rack.

8. A power actuated wrench comprising a wrench head supported for rotation, a worm gear drive for said head disposed to rotate the same, a reversible rotary hydraulic motor connected to the drive worm for said worm gear drive to rotate the same at high speed under low torque forces on the wrench head and having a stall point when a substantially predetermined torque force is reached, a double acting reciprocating hydraulic cylinder and piston motor connected to said drive worm to move the same longitudinally as a gear rack to apply additional torque forces to said wrench head uponstalling of said rotary motor, a closed circuit hydraulic power system for said motors comprising a liquid reservoir, a pump drawing liquid from said reservoir, and a master control valve connected between said pump and said motors and having an operable valve member movable to selected positions away from a neutral closed position for delivering power liquid from said pump to either side of the rotary motor and to either end of the reciprocating motor and for returning liquid from said motors to said reservoir, the delivery ports in said valve being disposed in relation to said movable valve member to effect operation of said rotary motor in one direction when said member is moved in one direction from neutral and in the opposite direction when said member is moved in the opposite direction from neutral and to effect cooperative movement of said reciprocating motor while maintaining torque on said rotary motor when said member is moved a second increment in the selected direction from neutral and the conducting line between said valve and one end of the cylinder of said reciprocating motor being divided into two parallel branch lines connected separately to said cylinder end, and an adjustable resistance-check valve in each of said lines disposed in opposite directions whereby the resistance valve in one line passes liquid into the end of the cylinder while the valve in the other line checks the passage of liquid into the end of the cylinder, and the resistance valve last referred to passes liquid discharge from said cylinder end whil the valve in the other line checks such discharge, said resistance valves being set to provide a predetermined pressure of liquid being distributed to said rotary motor during actuation of said reciprocating motor whereby the torque of the rotary motor will be maintained during such actuation.

9. A power actuated wrench comprising a wrench head supported for rotation, a worm gear drive for said head disposed to rotate the same, a reversible rotary hydraulic motor connected to the drive worm for said worm gear drive to rotate the same at high speed under low torque forces on the wrench head and having a stall point when a substantially predetermined torque force is reached, a double acting reciprocating hydraulic cylinder and'piston motor connected to said drive worm to move the same longitudinally as a gear rack to apply additional torque forces to said Wrench head upon stalling of said rotary motor, a closed circuit hydraulic power system for said motors comprising a liquid reservoir, a pump drawing liquid from said reservoir, and a master control valve connected between said pump and said motors and having an operable valve member movable to selected positions away from a neutral closed position for delivering power liquid from said pump to either side of the rotary motor and to either end of the reciprocating motor and for returning liquid from said motors to said reservoir, the delivery ports in said valve being disposed in relation to said movable valve member to effect operation of said rotary motor in one direction when said member is moved in one direction from neutral and in the opposite direction when said member is moved in the opposite direction from neutral and to effect cooperative movement of said reciprocating motor while maintaining torque on said rotary motor when said member is moved a second increment in the selected direction from neutral, an adjustable relief valve connected between said control valve and each end of said reciprocating motor draining power liquid to the reservoir, whereby the maximum power actuation of said reciprocating motor may be adjusted to provide a substantially predetermined torque actuation of into two line passes liquid into the end of the cylinder while the valve in the otherline checks the passage of liquid intothe end of the cylinder, and the resistance valve last referred to passes liquid discharge from said cylinder end while the Valve in the other line checks suchldischarge, said resistance valves being set to provide a predetermined pressure of liquid being distributed to said rotary motor during actuation of said reciprocating motor whereby the torque of the rotary motor will be maintained during such actuation.

10. A power actuated wrench comprising a wrench head supported for rotation, a worm gear drive for said head disposed to rotate the same, a rotary motor connected to the drive worm for said worm gear drive to rotate the same at high speed under low torque forces on-the wrench head and having a stall point when a substantially predetermined torque force is reached, a reciprocating motor connected to said drive worm to move the same longitudinally as a gear rack to apply additional torque forces to said wrench head, and means to actuate said reciprocating motor upon stalling of said rotary motor, means disposed to support said wrench head for limited axial movement between a retracted inoperative position and an extended operative position, and means operated in correlation to the operation of said motors and interlocked therewith and dis posed to provide for the automatic extension of said wrench head to operative position at all times during actuation of said motors and for the automatic retraction of said wrench head to inoperative position at all times when said motors are inoperative.

11. A power actuated wrench comprising a wrench head supported for rotation, a worm gear drive for said head disposed to rotate the same, a reversible rotary fluid operated motor connected to the drive worm for said worm gear drive to rotate the same at high speed under low torque forces on the wrench head and having a stall point when a substantially predetermined torque force is reached, a double acting reciprocating piston motor connected to said drive worm to move the same longitudinally as a gear rack to apply additional torque forces to said wrench head, means to initiate actuation of said reciprocating motor to advance said worm upon stalling of said rotary motor, means to supply power fluid to said motors to operate the same in correlation, a shaft carrying said wrench head, means disposed to support said wrench head shaft for limited axial movement between a retracted inoperative position for the head and an extended operative position, a piston coupled to the inner end of said shaft by means of a rotary bearing providing for relative rotation between the shaft and piston, a cylinder in. which said piston operates, a spring biasing said piston in a direction to retract said shaft and, wrench head to inoperative position for the latter, and a fluid passage from said power fluid supply to said cylinder to move said piston against said spring and extend said shaft and wrench head to operative position when power fluid is supplied to said motors.

12. A power actuated wrench comprising a wrench head supported. for rotation, a worm gear drive for said headv disposed to rotate the same, a reversible rotary fluid. operated motor connect ed to the drive wormv for said worm gear drive to-rotate thesamezat high-speed under lowtorque forces on the wrench head and having a stall .point whena substantiallypredetermined torque force is reached, a .doubleacting reciprocating piston motor connected to said drive worm to move the same longitudinally as a gear rackto apply additional torque forces to said wrench head upon stalling of said rotary motor, means to supply power fluid to said motors to operate the same in correlation, said means including a manually operated control valve adapted to selectively distribute power fluid either to said rotary. motor alone to operate the same in either direction or to both said motors simultaneously to operate the same in a mutually correlated direction for applying high torque to said wrench head, ashaft carrying said wrench head, means disposedv to support said wrench head shaft for limited axial movement between a retracted inoperative position for the head and an extended Operative position, a piston coupled to the inner end of said shaft by means of a rotary bearing providing for, relative rotationbetween the shaft and piston, a cylinder, in which said piston operates, a spring biasing said piston in a direction to retract said shaft and wrench head to inoperative position for the latter, a fluid passage from said power fluid supply to said cylinder to move said piston against said spring and extend said shaft and wrench head to operative position when power fluid is supplied to said motors, valve means in said last named passage for alternatively connecting said cylinder to said power fluid supply and to drain, and means disposed to be operated in correlation to said first named valve to operate said last named valve means.

13. In combination with a lathe having an electric motor driven spindle and a scroll type chuck carried by the spindle, a power actuated wrench disposed adjacent. said chuck to operate the same to successively grip and release workpieces for lathe operation and having a rotary wrench head adaptedto be extended into a socket in the perimeter of the chuck for adjusting the latter when the chuck is not rotating and to be retracted from said socket to permit rotation of the chuck after adjustment of the latter, an electrical supply circuit for said motor having a main switch, therein, a normally closed cut-out switch in said circuit, and means disposed to open said cut-out switch upon extension of said wrench headinto operative engagement with said chuck socket.

14;. The power actuated wrench of claim 1 in which the rotary motor is hydraulic and means are provided to adjust the fluid supply for driving the same to adjust the stall point for the motor.

LORENZ ALBERT LEIFER.

REFERENCES CITED The following references are of record in th file of thisv patent:

UNITED STATES PATENTS Number Name Date l, 823, i26 Ferris Sept. 15, 1931 1,831,225 Bogart Nov. 10, 1931 2,180,488 Van Hamersveld Nov. 21, 1939; 2,384,399 Reynolds Sept. 4, 1945 2,501,542 Sheldon Mar. 21, 1,950

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