US2100564A - Method of producing a pulling stress and hydraulic pulling mechanism - Google Patents

Description

Nov. 30, 1937. s. MANDL ET AL 64 METHOD OF PRODUCING A PULLING STRESS AND HYDRAULIC PULLING MECHANISM Filed Margh 16, 1935 3 Sheets-Sheet 1 Nov. 30, 1937. s. MANDL ET AL METHOD OF PRODUCING A PULLING STRESS AND HYDRAULIC FULLING MECHANISM Filed March 16, 1955' 5 Sheets-Sheet 2 Ec Zzz/afd M Hausa?" Nov. 30, 1937. s. MANDL ET AL 2,100,564

METHOD OF PRODUCING A PULLING STRESS AND HYDRAULIC PULLING MECHANISM Filed March 16, 1955 3 Sheets-Sheet 3 JQz/en Z'orv ziegmund/wandl, Ewan 1P awe)".

Patented Nov. 30, 1937 PATENT OFFICE IiIETHOD 0F PRODUCING A PULLING STRESS AND HYDRAULIC PULLING MECHANISM Siegmund Mandi and Edward M. Pfauser, Milwaukee, Wis., assignors to Blackhawk Mfg. 00., Milwaukee, Wis., a corporation of Wisconsin Application March 16, 1935, Serial No. 11,514

24 Claims.

This invention relates to hydraulic pulling mechanisms, and more particularly is directed to. a pulling mechanism whereby hydraulic force is applied in controlled quantities to displace or deform metal frame members, specifically for bending and straightening such members.

Heretofore, the application of hydraulic pressure for such operations has been extremely difficult, due to the impracticability of position- 'ing the hydraulic pressure-applying unit in a location suchthat the full effective force developed by the unit can be utilized for the pulling operation. Bending and twisting stresses incident to the development of a hydraulic pressure in devices heretofore employed have been transmitted directly to the unit, tending to make its positioning both precarious and dangerous to the operator. 'Further, in operations of this type, spacial limitations prevent the proper use ofhydraulic jack units of the type now employed in garages, repair shops and similar establishments.

We have found that in order to securethe most advantageous application of hydraulic pressure it is distinctly desirable to dissociate the pressure applying or pulling mechanism from the source of pressure supply, or pump unit. This feature has been brought out in suitable detail in the copending application of Edward M. Pfauser, Serial No. 4,728, filed February 4, 1935, in which the provision of a metal straightening machine including a power unit of general utility for the application of hydraulic force to the straightening disclosed.

The present invention contemplates the provision of 'a pulling mechanism wherein the entire available hydraulic pressure may be utilized for the pulling operation, and no portion of this force need be dissipated in maintaining the mechanism in position, or in absorbing and overcoming the bending and twisting stresses developed at the pump unit. In furtherance of this concept, we provide'a pulling mechanism or bending of metal members is to our knowledge, heretofore been incorporated. in a mechanism employing a portable ram or power unit dissociated from the pressure supply or pump unit. In the present invention, the ram unit comprises a pressure cylinder and an axially reciprocating plunger mounted therein and movable in'response to fluid pressure manually de-- veloped and controlled by a pump unit disposed at a remote point, the pressure being transmitted to the power unit through a flexible'conduit that prevents the transmission of stresses from the pressure developing unit to the power applying unit. As disclosed fully in the Pfauser application aforesaid, the ram unit is operable in any desired angular position and is thus all-directional in use.

Further, the particular manner of connecting the power unit for operation provided by the present invention possesses certain distinct advantages not heretofore obtainable. The mechanism is capable of alining itself automatically into operative position, and permits the pulling force to be. exerted in a direction such that maximum pulling effect per unit of force applied is produced.

Another feature of our invention, which is of distinct advantage, is the provision of adjustable coupling means whereby the'machanism is capable of adjustment in accordance with the spacing between the two members between which relative movement is to be effected, in order to accommodate the mechanism to various spacing between such members. In addition, we preferably provide a link or chain connection of the mechanism to the members, so that the pulling effort is exerted through non-rigid means, and thus the direction of pull is preferably at all times along a line extending substantially normal to the plane of the member being pul1ed, which is distinctly advantageous in applying force for this purpose.

In order to provide meansforrapid and simplified connection of the pulling mechanism in operative position, we provide, in the present invention, a novel type of chain-pull plate, one of the plates being preferably secured to the base or fixed end of the power unit, while the second plate, of similar design, is secured to the projecting end of the power plunger. Thus, upon extension of the plunger due to the application of hydraulic pressure to the power unit, the plates are moved away from each other, providing a commensurate pulling force between the members about which the chains have been s cured i We have found that in straightening of metal members frequent sighting or measurement of the deflection of the members is desirable, in order to secure accurate bending or straightening thereof. By the provision of a graduated plunger in the power unit, we are able to secure a positive indication of the deflection of the member being bent or straightened, and can thus determine to a quite accurate degree the exact amount of pressure which is applicable for predetermined displacement of the metal. This allows the operator to judge the deflection of the member without the necessity of auxiliary sighting apparatus, and prevents overstressing of the metal, or bending of the member to an extent, greater than that desired.

The present invention is of relatively simple mechanical design, employing a small number of parts, and is capable of rapid connection into and disconnection from its operating position, whereby its use in garages, repair shops and similar establishments is of .distinct practical advantage.

Other objects and advantages secured by the present invention will be described in detail in connection with the following specification,

, which, taken in connection with the accompanying drawings, will disclose to those skilled in the art the particular construction and operation of a preferred form of our invention.

In the drawings:

Figure 1 is a perspective view of the pulling ly on line 5--5 of Figure 4, showing in detail the construction of the pull plates;

Figure 6 is a perspective view showing a somewhat modified pulling mechanism embodying the present invention;

Figure 7 is a top plan view of one of the chainpull plates shown in Figure 6; and

Figure 8 is a sectional view taken on line 8-8 of Figure 7.

Referring now in detail to the drawings, in Figure 1 we have disclosed the application of our hydraulic pulling mechanism to the straightening of a front axle assembly of an automotive vehicle.

The front axle is indicated at 5, and is provided with rearwardly extending radius rods 6 forming a substantially V-shaped structure. The

axle 5, in this embodiment of the invention is shown as being bent outwardly, and the mechanism which we have provided is for the purpose of pulling the axle 5 inwardly toward the joined ends of the radius rods 8.

The pulling unit, as shown more particularly in Figure 2, comprises a hydraulic ram unit 1 having a base portion 8 and an axially extensible plunger 9, the ram unit being of the type described in detail in the above-identified copending application of Edward M. Pfauser.

.The base 8 of the ram I is provided with a threaded recess adapted to receive a coupling member l0 threaded thereinto, and having bearing engagement within a pressure plate l2 secured thereto. A pair of yoke rods l3 are secured at one. end in suitable opposed openings in the plate l2, and are prevented from axial displacement out of these openings by means of nuts l4 threaded onto the ends of the rods.

The plunger 9 of the ram unit has a threaded head portion l5 extending into a suitable pull plate l6 having opposed openings receiving the rods l3, the pull plate l6 being adapted for sliding movement longitudinally of -the rods.

The rods l3 are extended outwardly of the pull plate I6 for any desired distance, and adjacent their outer projecting ends are provided with a second pull plate ll, of the same general form as the pull plate 16, which is mounted for movement on the rods I 3 by means of opposed openings formed therein, the plate I! being prevented from displacement outwardly of the rods by means of a pair of nut members l8 threaded onto the projecting ends of the rods.

The ram unit I comprises a ram cylinder flexible fluid pressure transmitting conduit 28 coupled as at 22 to the base 8 of the ram unit. This coupling provides communication between the hose 2!! and the interior of the ram cylinder. The flexible conduit 20 at its opposite end, is coupled to the outlet port 23 of a pump unit 24,

the pump unit 24 being of the type disclosed in detafl in the above-mentioned copending application of Edward M. Pfauser.

The pump member comprises a pump cylinder or reservoir containing the fluid to be placed under pressure, and a rocking beam 25 adapted to be rocked about pivot 26 by means of an actuating lever 2'! to produce reciprocation of the pressure plunger within the head end 28 of the pump unit, thereby drawing fluid from the reservoir of the pump unit and transmitting it under pressure to the conduit 20 through the outlet port- 23. The pump unit 24 is provided with a laterally projecting foot portion 29 at its forward end, adapted to be engaged by the foot of an operator, and a clamping member 30 at its rearward end having an upwardly disposed foot portion 32 adapted to be engaged by the opposite foot of the operator, whereby the pump unitmay be mam adapted to receive fluid under pressure from a tained in flxed position on thefloor during reciprocation of the operating handle 21.

The present invention is not concerned primarily with the details of the pump construction, and reference may be made to the above-mentioned copending application for a fuller explanation of the operation thereof.

The ram unit I, as shown in Figure 1, is disposed within the triangular structure formed by the axle 5 and the radius rods 6, and the plate I6 is provided with opposed chain latching portions adapted to receive the opposite ends 34 and 35 of a chain member which, at its intermediate portion, is wrapped around the juncture36 of the radius rods. The ends 34 and 35 of the chain may be adjustably'secured in fixed locked position upon the plate I6, whereby actuation of the plunger 9 due to 'fluid pressure within the ram cylinder results in movement of the plate l6 outwardly along the rods l3, thereby placing tension upon the chain between its fixed clamped ends 34 and 35 and theportions 36 thereof.

Similarly, the plate member I! is. provided with chain gripping portions 31, receiving the ends 38 and 39 of a second chain member 40, wrapped It is apparent, therefore, that upon reclprocation of the actuating handle 21 ofthe pump unit the left, as shown by' the arrow in' Figure 2. This results in the plates l6 and I1 having relative movement towardeach other when pressure is applied "to theiram' -unit, which results in shortening the distance between the portions 36 and 42 of thechains', and producing a pulling tension uponthe axle 5 tending toibend'and/f straighten the same;

The plunger 9' is preferably provided with' graduated indicationsfas shown in Figure 2, and the operator, standing at the pump unit 24, can

actuate th e pump-21 and thus control the amount of pressure transmitted to the unit 1. At the" same time, by noting theggraduations on the plunger 9, anypredetermined defiection of the;

axle or other membefj5fcanbe produced. Thus, if the operator has ascertained'that'a sponding movement of the plunger 9, indicated by the graduations thereor'i, whereby the deflection of the" member 5 may beaccurately con-" trolled. Further, itfis'to be notedthat the de- -velopment of pressure at the pump unit 24, which produces stresses at the pump unit, will not act to transmit these stressesto the ram unit 1, inasmuch as the flexibleconduit is interposed therebetween. [This conduit 20 is pre'ferably' formed of a suitable metal reenforced cable provided with a rubber or other resilient body por-' tion.

Referring now to the structure shown in' Figure 3, the ram unit 1 of this embodiment of the invention has its base 8 provided with a suitable coupling member to which a chain pull plate 48 is directly secured. At its opposite end, the ram plunger 9 is threaded into a depending socket portion 50 of a second chain pull plate 52 shown in detail in Figures 4 and 5. The two plates 48 and 52 are substantially ident cal in design, and correspond to plates l6 and H of the embodiment shown in Figure 1.

Considering now Figures 4 and 5 in detail, the

pull plate 52 is provided with a plurality of radially extending tongue portions. one pair of tongue portions 53 being provided with openings 54 adapted to provide guiding means for chain members, such as the chain members 55 and 55 of Figure 3, therethrough.

Extending at right angles to' the opposed tongues 53 are a pair of d ametrically opposed lug members 51, which members are provided. at

their ends, with inturned spaced edges 58 defining slots 59 extending radially inwardly toward the center of the plate. Suitable web portions 60 are formed centrally of the members 51, and extend to the defining edges of the slot 59, forming recessed slotted sockets adapted to "secure chain links therein. As shown in Figure 3, a link member is adapted to slide laterally into the slot 59, and the adjacent link members then have abutting engagement against the web portions 60 for limiting movement of the chain member with respect to the plate.

The plate 52 is internally threaded within the V 9.5m" chain 40, whereby the plate jl1;tends-to-move to cylindrical opening 53.

socket projection 50 to receive the threaded end 15 of the ram plunger 9, and above this portion is an annular recess 62 forming a slight clearance for threading of the ram plunger 9 into and out of the plate. Above the recess 62 the plate .52 is provided with a central cylindrical bore 63 extending to the outer surface of the other side of the plate, and providing a socket for receiving a drift pin 64 or the like, employed for punching or pressing out wrist pins, bearings andthe like. A suitable threaded radially extending opening 65 is provided between two of the extending leg portions of the plate 52, and extends into the The opening 65 is adapted to receive a suitable set screw 66 which is threaded thereinto to have bearing engagement against the surface of a pin such" as the pin 64, to secure .and hold-ithe pin in'fixed position withrespect to the plate, preventing its displacement from the plate when the plate is. reversed in posi-lv tio'n.

In the production of pulling .force between two i members, such as the members 12 and =15 "of-' Figure 3, which maybe-spaced members adapted f'to be pulled together, or"may comprise a fixed e c't o of two inches of the center of 'the'axle 5 an-'r'espect to its formerpositionis desirablejhe ma actuate the pump unit 24 to" producea corresupporting member and a second member which is to be bent or straightened, or pulled toward the tween the members 12 and 13, and the plates 48 and 52 are secured to the base 8 of the unit and to the plunger 9 thereof; respectively. The chains 55 and56 arev then secured inthe position shown, the chain 55 being wrapped about, the member 13, having .its ends guided for movement in the 1 openings 54 of the plate 48, and then extending along the ram unit on opposite sides thereof and being locked in .fixed position within the slots 59 of the plate 52. The chain .56, on the other hand, has its intermediate portion wrapped around the member 12, and the ends thereof are extended i-hriough the guide openings 54 oil the plate 52, and are locked in fixed position in the slots 59 of the plate 48. Upon the application of pressure to the interior of the ram cylinder, the plunger 9 is moved axially outwardly of the cylinder, tend-' "ing to move the plates 48 and 52 apart. Since the overlapping ends of the opposite chains are secured to these plates, this produces a tension stress upon each of the chains, tending either to draw members 12 and 13 toward each other, or to draw either one of these members towards the other, if the other member is a fixed support.

It will be noted that there is no structure which prevents the independent movement of the ram unit 1 when connected in thismanner, and it is therefore apparent that upon the initial application of pressure to the unit, the unit will assume a position such that its axis lies in a line corresponding to the direction of pull between the members 12 and 13, whereby a straight line tension pull is exerted between these members. This is of material advantage in providing for maximum exertion of pulling force by the unit in accordance with the pressure applied thereto.

Inasmuch as the slots 59 of the-two pull plates are adapted to receive any of the links of the chain members, these chain, members may be readily adjusted to the desired lengths necessary for proper spacing of the ram unit 1 betweenthe thereby elongating the ram unit 1, if the spacing .of the members 12 and 131s such as to require such extension. However, ordinarily the lengths of the chains can be varied sumcientlyto provide for operation of theramunit within any desirew spacing of members to be bent or straightened.

Referring now in rnore detail to' the'structure shown in Figures 6, '7 and- 8; the ram unit"! is pm: vided, at its base 8, with a chain" pull plate-'18,

which is shown in more detailinFigures 7 and 8. The chain pull plate 18 has a projecting cylindrical portion 12, internally threaded as at 13 provided with oppositely extending arm portions 14 and I5, which arm portions have guide openings 18 extending therethrough, the openings 18 being for the purpose of providing guiding passages for the chain members which secure the ram in pulling position. Projecting upwardly in a direction opposite to the cylindrical portion 12. of the pull plate 18 is aiboss 11, which boss defines an opening 18 out of the plane of arms I4 and I5 and extending in a direction normal to the axis of the openings 18.

In the operation of the mechanism shown in Figure 6, one of the pull plates 18 is secured to the base 8 of the ram unit I by means of a coupling member or the like, while the other pull plate T8 is secured to the threaded head of the axially movable plunger 8 carried by the ram unit. A chain member 19 has the intermediate portion thereof extending through the opening.

18 of the pull plate 18 carried by the plunger, as shown at 88, and the two-extending ends of the chain member 19 pass throughthe guide openings 16 of the pull plate connected to the base of the ram unit,one end of the chain being provided with a hook member 82 adapted to engage in and secure any suitable link of the opposite end 83 of the chain [9, whereby the chain may be adjustably hooked about any suitable member'to be bent or straightened, suchas the member 84. By the provision of the hook 82, it is apparent that the chain 18 may be carried by the ram unit, as the ram'unit is moved into various positions, and all that is required to connect it to the member to be operated upon is to hook the hook 82 in the desired link of the end 83 of the chain 18, whereby the ram unit is adjustably secured in proper position with respect to the member 84.

Similarly, a corresponding chain member 85 has the intermediate portion 86 thereof passing through the opening 18 in the pull plate 18 carso that it may be hooked about a support in the same manner in which the. chain I9 is secured, if desired. By merely unhooking the hooks 82 and 98, the ram unit, together with the .chains, maybe placed in any desired positionQthe chains being engaged in the bosses l1 and threaded through the openlngs'l6 so that a minimum of time is required for connecting the unit in position.- .1 5;

'The operation of the. mechanism showrliin Figurer6 is similar to that describeddmconnection,

withFigure 3, the application 5! pressure through the conduit 28 to the ram unit 1 causingextension of the plunger 9, which. in turn produces a tension pull upon the chain 19, andacorrespond ing thrust against the base of the ram unit, producing a tension pull upon-the chain 85. Asa result, the plates 18 tend-tomove away from each other, and thus tend to draw; the secured ends 82, 83 of the chain 19 andgthe ends 81, 88 of r the chain 'toward each other, thereby producing a pulling stress upon the members 84 and-89, which pulling stress can be regulated asdesired by the operator, by means of theindications produced by the graduations on the annular surface of the plunger 8, and the pressure-being applied to the unit through the conduit 20.

It is therefore believed apparent that we have provided a ram pulling mechanism capable of producing a bending or straightening of any desired metal members with the maximum amount of force per unit of pressure applied to the and in which the pulling force islexerted in a line substantially in the directionof desired pull.

The unit is capable of rapid adjustment and connectionbetween variously spaced, members, facilitating its use for a large number of operations,

could be employed for pushing the membersj'i2 and I3 apart, if such operation were desired. i,

While we have'disclosed the ram unit as particularly applied for pulling mechanism, therefore, we do not intend to be limited to theexact operation and connection of the members asshown and described, but only, in so far as vdefined by the scope and spirit of the appended claims. I

Weclaim: r. v

1. In a mechanism of the class described com: prising a power unit including an axially movable plunger, separate means carriedbytsaid plunger and at the opposite end of said unit for receiving separate chain members,-each of said means in, cluding means for guiding themovement .of,;the chain member, secured to .the.-ot l 1er,o f,said means, and a flexible conduit connectedtolsaidjunitlfor supplying liquid under pressurathereto'to. move, said plunger outwardlypf said jufniti,

2. In a -mechanism,of'the,class'described, a power unit, chain-pull plates at opposite ends of said .unit chain-fmembers having their inter:

mediate portion's'looped about. spaced metal members and having. the extending ends thereof secured to said plates, and means for applying hydraulic pressure to said unit for moving said plates away from each' other to produce a tension stress upon said chain lmembers between said spaced metal members.

3. In a mechanism of theclass described, a portable ram unit, pull plates at opposite ends thereof having laterally spaced latching portions, separate flexible tension members each secured to the latching portions oi the pull-plate at one end of said unit and extending alongside and then outwardly beyond theiopposite end of said a bers, and means for expanding said unit axially to move the secured ends of said tension members away from each other whereby a tension stress is produced between said metal members.

4. In a mechanism of the class described for producing a tension stress between two spaced members, a portable ram unit capable of being placed between-said members, chains connected to each end of said unit and extending outwardly of the opposite ends of said unit for connection to said members, and means at said opposite ends of said unit for guiding the extending portions of said chains whereby uponaxial extension of said ram unit said chains automatically aline' said unit in the direction of the tension stress between said spaced members.

5. In combination, a power unit comprising a ram cylinder and a ram plunger movable axially outwardly of said cylinder, chain plates on said plunger and said cylinder, chains carried by each of said plates and passing through the other of said plates ,for connection to a pair of spaced members, and means for transmitting hydraulic pressure to said cylinder to expand said power unit axially whereby said' chains exert a pulling stress between said spaced members.

6. A chain-pull plate for a pulling mechanism of the class described having a central threaded guiding means in the recess, a pair of opposite disposed guide means spaced from said recess, and a pair of chain-engaging lug portions disposed on opposite sides of said recess and extending normally to'said guide means. i

'7. A chain-pullplate for a pulling mechanism of the class described comprising a plate member of generally cruciform shape, a threaded recess formed centrally in said plate member for attaching said member to a power unit, a pair of chain-engaging lug means formed in one pair of oppositely projecting'arms of said member, the other pair of oppositely projecting arms having guide'means formed therein capable of slidably receiving chain members.

8. A chain-pull plate for a pulling mechanism of the class described comprisinga central portion having an internally threaded recess therein, four arm portions projecting radially outwardly of said centralportion,chain-engaging lug meansin two'of said arm portions, and chain other two of saidarm portions. F

9. In a mechanism of the class described, a power unit, a pump unit for developing a hydraulic pressure, flexible fluid transmission means between said units, said power unit comprising a base portion having a plate secured thereto, a chainconnected to said plate and looped about a metal member, a plunger in said power unit, a plate secured to the projecting end of said plunger, and a chain connected to said plate and looped about a second metal member,

said plunger moving outwardly of said base portion upon transmission of pressure to said power unit for producing a tension stress upon said,

chains between said-metal members.

10. In a pulling mechanism of the class described, a power applying unit comprising a ram cylinder and an axially movable plunger, a chainpull plate carried by said cylinder, a chain-pull plate carried by said plunger, means for securing chains to said plates, said chains being looped about a pair of spaced metal members, and means ata point remote from said unit for developing a hydraulic pressure including means for transmitting said pressure to said power unit independently of stresses incident to development of said pressure whereby said plunger is moved outwardly of said ram cylinder to produce a tension stress on said chains between said members.

11. In a pulling mechanism of the class described, a ram unit comprising ;a ram cylinder and an axially movable plunger therein, chain-' pull plates carried by' said cylinder and said 12. The method of. pulling two spaced members toward each other which comprises connecting chains to each of said members, movably supporting the end of each chain with the adjacent portion of the other chain in overlapped position between said members, and spreadingthe supported ends of said chains apartto exert a straight line pulling stress between saidspaced members to reduce the spacing between said members. v

13; Themethod of producing a pulling stress between two spaced members which comprises securing tension means to said members, extending the ends of said means into the space between said members in overlapping relation, connecting the extending portions of said means to opposite ends of a power unit so that the tension means from one of said spaced members extends alongside said power unit and is connected tothe far end thereof, the other tension means extending from the other spaced member alongside said power unit and being connected with the opposite end of the latter, and hydraulically expanding said unit to separate said ends and pull the portions of said tension means engaging said members toward each other.

14. The method of producing a pulling stress between two spaced members which comprises wrapping chains about said members, extending the ends of said chains into the space between said members, connecting the extending portions mote from'said members, transmitting said pressure to said unit independently of stresses developed at said remote point, and hydraulically expanding said. unit by said pressure to pull the portions of said chains engaging said members toward each-,other.

15. In combination, a power unit comprising a ram cylinder and an axially movable ram plunger therein, a plate secured to the base of said cylinder, a pair of rod members carried by said plate and extending along opposite sides of said cylinder past the opposite end thereof, a second plate secured across the extending ends of said rods, a third plate slidably mounted on said rods intermediate the cylinder and the ends of said rods and secured. to said plunger, chain means wrapped around a metal member and connected to said second plate, chain means wrapped around a second metal member and secured to said third plate, said power unit being placed between said' metal members, and means for hydraulically moving said plunger outwardly of said 16. In combination, a power unit comprising a ram cylinder and an axially movable ramplungertherein, a plate secured to the base of said cyl-' inder, a pair of'rod members carried by said plate and extending along opposite sides of said cylinder past the opposite end thereof, a second plate secured across the extending ends of said rods, a; third plate slidably mounted on said rods intermediate the cylinder and the ends of said rods and secured to said plunger, chain means wrapped around a metal member and adjustably connected to said second plate, chain means wrapped around a second metal member and adjustably secured to said third plate, said power unit being placed between said metal members, means remote from said unit for developing a hy-' chains carried by each of said pull plates and guided for movement through the opposite pull plate, and means at theextending ends of said chains for securing them to metal members spaced away from opposite ends of said unit.

18. A chain pull plate comprising a central portion having an internally. threaded recess therein, a pair of oppositely extending arm portions having guide openings therethrough, and

7 an intermediate axially projecting boss portion members, applying a separating force to the opposite said recess having an opening extending therethrough normal to the axes of said guide openings and intermediate said arm portions. v

19. The method of pulling two spaced members toward each other'which comprises connecting flexible tension members toeach of said spaced members, overlapping the ends'of said flexible spaced apart ends of the overlapped portions of said flexible members in alignment with the latter-so'as to force the overlapped ends of said tension: members apart to exert a pulling stress be tween said spaced members, and supporting the force applying means on said flexible tension members at points spaced around the ends- 20. In a pulling mechanism of the class described, a ram unit having an axially movable plunger, a plate membersecured to the base of said unit, a second plate member carried-by said movable plunger, there being openings formed in, said second plate member, tension transmitting means carried by said second plate member and extending alongside said ram unit and adjacent said first plate member, and tension means connected with said first plate member and extending alongside said unit in a direction opposite to said first mentioned tension means outwardly of the unit through the openings in said second mentioned plate member.

21. In a mechanism of the class described, a power unit, pull plates at opposite ends of said unit, flexible tension members having their outer end portions connected with spacedmetal members and having their inner ends extending in overlapped'relation and secured, respectively, to

the furthermost pull plate, and means for applying hydraulic pressure to said unit for moving said plates away from each other to produce a tension stress upon said flexible members between said spaced metal members for pulling the latter toward each other.

22. A pull mechanism for producing a tension stress between two spaced memberscomprising a first device for developing a hydraulic pressure directly under thecontrol of the operator; 9. second device mechanically disassociated from said first device-and operable in any desired angular position for producing a straight line force, means coupling said members in overlapped relation to opposite ends of said second device;

and a third device comprising a flexiblepressure transmitting member connecting said other two I devices and transmitting pressure from said first device to said second device independently of stresses produced by development of sure at said'flrst device.

23. I'he-method of pulling two spaced members toward each other which comprises engaging each of said members by a flexible tension member, overlapping the tree portion of said tension members','connecting said overlapped portion tothe opposite ends of expansible means,- supporting said means in position between said a spaced members in the line of stresstherebetween on portions of said tension members inter- I mediate said spacing members and the points of connection of said tension members to said means while PI'OVidiIlEfl-GB movement of said Hi intermediate portions of said tension members with respect to said means, and expanding said means to pull the engaged portions of said tension members toward each other.

' 24.'In' an assembly for pulling two spaced members toward each other including a ram unit comprising a cylinder and an axially extensible piston carried thereby and having pull plates secured to the'base of said cylinder and to the outer end of said piston, the method of producing a tension stress between said members which comprises engaging each or said members by flexible tension means, connecting each tension means to opposite sides of the pull 'plate disposed remote from the member with whicli'the tension means is engaged with the in-- termediate portions of said tension means in overlapped position along the sides of said unit, guiding said intermediate portions of said tension means for movement relative to said unit' on the ends of said unit adjacent the member with which each of said tension means is en-- gaged to thereby support said unit on said ten*- sion means in line with the direction of stress.

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