US1964023A

US1964023A - Tube pulling device

Info

Publication number: US1964023A
Application number: US694544A
Authority: US
Inventors: Armstrong Robert
Original assignee: Individual
Current assignee: Individual
Priority date: 1933-10-21
Filing date: 1933-10-21
Publication date: 1934-06-26
Anticipated expiration: 1951-06-26

Description

June 25 193% R. ARMSTRONG TUBE PULLNG' DEVICE 1953 2 Sheets-Sheet Filed Oct. 21

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TUBE PULLING DEVI CE Filed Oct. 2l, 1933 2 Sheets-Sheet 2 1.5' 51/ w34 n) fj 'W j V 7J l J l 157 l /s-f/ u@ l 22 Z1 `F10 (40 4% 25 .56 Eg 5 67 5f 15 45 11 W7 hw f" K L] w l/ /l 22 hm 5 "Q0 C36 26 .///z

{NVENTOR ATTRN Patented June 26, 1934 TUBE PULLING DEVICE Robert Armstrong, Ridgefield, N. J.

Application Gctober 21, 1933, Serial No. 694,544

12 Claims.

My present invention relates generally to tools, and has particular reference to a tool or device for pulling tubes from a tube sheet.

It is a general object of my present invention to provide a tube pulling device of the character illustrated in my Patent No. 1,717,487, issued June 18, 1929, the present invention embodying a number of improvements which render the device more compact, more ecient, more fully automatic, and much simpler to operate.

Although I have illustrated and shall hereinafter describe a device which is primarily designed for the removal of tubes from a surface condenser, nevertheless it will be understood that l5 as to certain phases of my invention a specific application of this character is not essential.

A surface condenser is ktypical of the devices which employ a multiplicity of tubes and which .require a periodic tube replacement. Usually,

2o the tubes are arranged in a parallel group, supported at their ends by two tube sheets. When the tubes corrode or become otherwise worn out, a withdrawal of the tubes, to permit replacement thereof, becomes necessary.

In my earlier tube pulling device, I have providedv an engaging means insertable into a tube to be pulled, a means for thereupon causing engagement of the tube, and a piston-cylinder arrangement for thereupon permitting an expansible uid medium to be operatively interposed between the tube sheet and the engaging means for withdrawing the latter out with respect to the tube sheet; While such device is usually capable of operation by a single operator, per- ;5 mitting him'to initiate the withdrawal of tubes in rapid succession, it has frequently been found expedient to employ two workmen for this purpose, principally because the weight of the tool makes it preferable for one operator to control L0 the engaging means while a second operator controls the piston-cylinder operation.

By means of my present improved tube pulling device, a single workman may, with great facility and ease, control the entire operation of the de- .5 vice. This is due to the fact thatI have provided an improved arrangement lof parts whereby the tube pulling operation is almost entirely automatic. More particularly, an operator of the present tool is required to do nothing more than l `0 to insert the tube engaging means into the tube to be pulled, and thereupon to turn a valve or similar control member, The present device is adapted automatically to effect a tube engagement, to withdraw the tube, and finally to eifect 5 a tube disengagement. By withdrawal 'of tube",

(CL Ztl-88.2)

as this term is used herein and in the appended claims, I refer to a mere initiation of tube Withdrawal, since it is the initial dislocation and movement of the tube which has heretofore presented the greatest difculty. The tubes designed to be pulled by my device are approximately twenty-five feet in length, possibly more or less, and when an'initial withdrawal of the present character has been eiected, a workman following in the path of the operator of the pres- 65 ent device may withdraw the tubes completely with relative ease.

Briefly, my present device comprises a claw insertable into the tube to be pulled, and a single exteriorly controllable means for successively effecting an engagement of, the tube by the claw,

a withdrawal of the engaged tube, and a final .disengagement of the tube by the claw. The

term claw is intended to refer broadly to a plurality of teeth or biting elements, or their equivalents, as will be readily understood by those skilled in the art.

More particularly, my present invention involvesthe provision and arrangement of a main movable member which controls the withdrawal so of the claw; an auxiliary member mounted for relative movement with respect to the main member; a means operable by relative movement of said members for controlling the tube engaging operation of the claw; and a means for automatically producing, in proper succession, rst a relative movement of the members for effecting' tube engagement, then a movement ofthe main member for withdrawing the engaged tube, and finally a reverse relative movement of the members `for effecting disengagement of the lwithdrawn tube.

Other features of my invention lies in the particular arrangement and construction of parts hereinafter more fully described, whereby I am enabled to provide a device which is extremely 5 simple and yinexpensive from a manufacturing standpoint, easy and eilicient from an operating standpoint, and capable of achieving its contem-4 plated functions in a uniquely reliable manner.

I achieve the foregoing objects, and such other objects as may hereinafter appear or be pointed out, in the manner illustratively exemplified in the accompanying drawings, wherein- Figure 1 is a perspective view of a tube pulling device embodying the lfeatures of the present in- .05 vention; f

Figure 2 is a cross-sectional plan view of the device showing the parts in the relationship they assume during the pulling of a tube;

Figure 3 is a cross-sectional' view taken sub- .no

stantially along the line 3-3 of Figure 2; and

Figures 4-7 are views on a reduced scale, and partly diagrammatic, similar to Figure 2 and illustrating the relative positions of the various parts during operation of the device.

In Figure 2, I have shown a typical tube sheet 10 and a single tube 11 in process of being withdrawn. It will be understood that many hundred tubesare arranged in parallel relationship with their ends mounted in the tube sheet 10, and that the description herein contained with respect to the single tube 11 is merely illustrative of the procedure that takes place with each tube.

In my earlier patent, I have illustrated a tube whose end is maintained in liquid-tight association with the tube sheet by means of packing. Many of the modern installations employ tubes which are rolled into association with the tube sheet, as illustrated in my Patent No. 1,883,453, issued October 18, 1932. The present device is adapted to be used with any type of tube, whether it is packed or rolled into position, it being merely necessary to see to it that the tube engaging teeth that are employed (i. e., the claw of the device) are of the particular type best suited to engage any particular tube.

'I'he present device comprises, broadly, an elongated portion 12, a forward tube engaging portion or claw shown in the form of teeth 13, anda piston-and-cylinder arrangement 1-4 at the opposite end. 'I'hese elements will be presently described in greater detail, but I will men- `tion at this point that the operation of my present device requires nothing more than that the claw be inserted into the tube end and that the piston-and-cylinder arrangement be then rendered operative.

I have shown an elongated, axially bored member 15 provided at its forward end with four radially disposed recesses or grooves 16, arranged at substantially 90 to each other, andv two 0pposite ones thereof being shown in Figure 2. Pivotally mounted in each recess is a rocker having a rear arm 17, and a forward arm constituting one of the teeth 13. Each rocker is mounted upon a pivot pin 18 extending transversely across the recess within which the rocker is disposed. The forward portion of each rocker extends outwardly beyond the forward end of the member 15.

The teeth 13, collectively constituting the claw of the device, are adapted to be radially reciprocated to cause them to engage or disengage with or through the inner surface of a tube into which they are inserted. The direct mechanism for controlling this reciprocation is a longitudinally reciprocable rod 19 arranged in the bore of the member 15, the forward portion being externally threaded, as at 20, and extending considerably beyond the teeth 13. Mounted upon the forward portion of the rod is the adjustable wedge member 21 whose positional relationship upon the rod 19 is controllable and variable by means of the nut member 22 engaging the threads 20. The rearwardly disposed surface of the, member 21 is substantially conical, or, more accurately, pyramidal, so that a rearward movement of the rod 19 will cause the engagement of this surface with the rear surfaces of the teeth 13 to move the latter radially outwardly.

Immediately behind the recesses 16, the bore in the member 15 enlarges, and the rod 19 also enlarges, to provide a conical or pyramidal surface of wedge portion 23 disposed oppositely with respect to the forward wedge that has just been described. Forward movement of the rod 19 thus causes the engagement of the surface 23 with the rear surfaces of the rocker arms 17 to pivot the rockers so as to move the teeth 13 radially surface permits the extent of claw engagement to be controlled. Assuming the reciprocating movement of the rod 19 is constant, the nearer the wedge surfaces are together the greater will be the radial reciprocation of the teeth 13.

In accordance with my invention, the reciprocation of the rod 19, relative to the member 15, for accomplishing radial reciprocation of the teeth 13 in the manner hereinbefore described, is controlled by the relative movement of two members which have been shown in the form of a main piston 24 and an auxiliary piston 29 arranged in the cylinder 25. The main piston 24 is mounted upon the rear end of a piston rod 26, the latter having a collar 30 and a threaded end 31, and the piston having a recess adapted to bear against the collar 30 and having a second recess adapted to receive a securing nut 32 or the like. At its forward end, the piston rod 26 is threaded into the rear enlarged end 33 of a rod 27, a set screw 34 serving to^hold the rods 26 and 27 in firm permanent relationship. The forward end of the rod 27 is in turn screwthreaded into the rear, internally threaded end 28 of the rod 19, and a lock nut 35 is advantageously employed in this connection.

The auxiliary piston 29 is mounted upon a hollow piston rod 36 which is similarly provided with the collar 37 and the threaded end 38, the piston 29 having a recess which bears against the collar 37 and having a second recess adapted to receive av securing nut 39 or its equivalent. The forward end of the rod 36 is screw-threaded into the internally threaded, rear end of a member 40 which snugly accommodates the rear end 33 of the rod 27. Lock nuts 41 are preferably provided to hold the

parts

36 and 40 in predetermined desired relationship. The forward portion of the member 40 is screw-threaded, as 'at 42, into the rear end of the elongated hollow member 15.

The construction purposely provides for a relative movement of the pistons, one with respect' to the other, but this relative movement is limited in extent by the distance through which the rear end 33 of the rod 27 may move within the member 40. In other words, the showing of Figure 2 depicts the end 33 in abutment with the forward end of the rod 36; and the pistons are thus at their maximum separation. They may be brought into proximity or juxtaposition by an amount equal to the distance between the surface 43 of the member 40 and the surface 44 of the rear end 33 of the rod 27. This distance is capable of adjustment by means of the threaded 4tons, and hence of their respective piston rods, it

is preferable to provide the hollow piston rod 36 with the bearing portions 45 and to construct the corresponding portions of-the piston rod 26l with the two sets of circumferential grooves 46 and 47, this arrangement of parts being an obvious expedient, known per se, to prevent leakage of operating fluid between the inner piston rod 26 and the encircling piston rod 36.

Around the member 15 isan elongated sheath 48 screw-threaded at its rear end into engagement with the knurled sleeve 49,- the latter being in turn screw-threaded into engagement with the sleeve 50 which projects forwardly from the forward wall 5l ofthe cylinder 25. Preferably, the sleeve 50 is threaded, as at 52, into association with the wall 51; and I might mention at this point that the wall 51 is also associated with the packing 53 and a gland 54 through which the piston rod 36 extends. By adjusting the threaded engagement between the sleeves 49 and 50, and by employing the lock nut 55 to secure these sleeves in predetermined desired relationship, the effective length of the sheath 48 may be varied. The forward end of this sheath is adapted to bear against the tube sheet l0, thereby fulfilling a dual function, viz., to limit the extent of insertion of theteeth 13 into the tube, and to serve as a brace to permit an operating uid to withdraw the teeth 13 outwardly with respect to the tube sheet 10.

So far as the cylinder 25 is concerned, it is provided with a fluid opening 56 near its forward end and with a corresponding i'luid opening 57 near its rear end. A conduit 58 permanently connects the opening 56 with one side of a valve 59,A and a conduit 60 permanently connects the opening 57 with the opposite side of this valve. The valve includes an inlet opening 61 for a Working iiuid such as compressed air, steam, or the like, and an exhaust opening 62 which communicates with the atmosphere. The movable part of the valve, controllable by the handle 63, contains the arcuate port 64 and the opposite arcuate port 65. In the relationship shown in Figure 2,A a connection is thus established through the port 64 from the inlet 61 to the cylinder opening 56, thereby admitting working fluid or similar expansible medium to the left of the piston 29; and a connection is established, through the port 65. from the cylinder opening 57 to the exhaust 62.

In accordance with my present invention, and for purposes presently to be described, an adjustable by-pass 66 connects the conduit 58 to the uid inlet opening 67 arranged at the extreme left end of the cylinder; and a special outlet opening 68 is provided in the cylinder, communicating directly with the atmosphere, near the right hand end of the cylinder.

From the description thus far given, the manner of operation of the device will be clearly understood upon reference to Figures 4 to '7.

Normally, the pistons are at the extreme left end of the cylinder, i. e., with the auxiliary piston 29 practically abutting against the cylinder wall 5l. A leather buffer or the like 69 is preferably arranged at this end of the cylinder. The extreme left hand position of the main piston 24 positions this piston at a sufficient distance from the auxiliary piston 29 to permit the opening 56 to communicate with the space between the pistons. When the pistons are in their maximurn proximity, the left hand surface' of the main piston 24 abuts. against the leather buffer or the like '70 which is arranged between the pistons.

When iiuid under pressure is admitted into the conduit 58, it immediately enters the space between the pistons and causes an almostinstantaneous separation of the pistons, the extent of separation being limited, as hereinbefore described, by the abutment of the rear end 33 of the rod 27 against the forward end of the rod 36'. This relative movement of the pistons,.i. e., a separation of the pistons, effects a relative movement between the rod v19 and the member 15. More particularly, the rod 19 is moved rearwardly with respect to the member 15, thereby bringing the wedge 21 into operative engagement with the teeth 13 to force the latter radially outwardly.

If there were no arrangement for unbalancing the pressures on the outermost surfaces of the two pistons, no further piston movements would result, since the pressure forcing the main piston to the right would be exactly oounterbalanced by the pressure forcing the auxiliary piston toward the left. To effect an unbalance, and thereby permit further movement of the pistons, the by-pass 66 provides a slow-functioning means for admitting the iiuid to the left surface of the auxiliary piston 29. Since no such pressure is brought to bear against the outer or right hand surface of they main piston 24, a jointpiston movement is initiated which causes both pistons to` move `jointly toward .the rear end of the cylinder. The movement of the main piston 24 toward the right causes a corresponding movement of the piston rod 26 and the parts associated with it. The abutment cf the rear end 33 against the piston rod 36 causes a corresponding movement of all of the parts associated with the piston rod 36, notably the member 15 which carries the claw. Accordingly, the joint movement of the pistons causes a withdrawal of th'ejclaw (and hence of the engaged tube) with Y respect tothe tube sheet 10, it being recalled that ""the'sheath 48 serves `to brace the cylinder itself against the tube sheet 10. l

The opening 56 is purposely made of a width somewhat greater than the width of the piston 29,-so Vthat-'the Yiloyvcf fluid through the conduit 58 is never impeded, the fluid passing originally Iinto. the space betweenl the pistons, and, when unbalance has been effected, into the space behind the piston 29.

The joint movement of the pistons continues until the main piston 24 abuts against the leather buffer or the like 71 provided inthe rear wall of the cylinder. The outlet opening 68 is purposely positioned in a manner which permits the piston 24 to uncover it just as this extreme end of piston movement is reached. At this point of operation, the iiuid pressure between the pistons is permitted to exhaust through the opening 68; but since there is still a fluid pressure upon the left of the auxiliary piston 29, the latter is enabled to catch up with the piston 24, .thereby again bringing about an approach or juxtaposition of the pistons. During this appreach of the pistons, the rocker armsl'? are caused to ride up the wedge 23, thereby bringing about a retractive movement of the teeth 13 to.

release the tube.

To restore the parts to their normal position, 1

matically illustrated Figures 4-7. In Fig- 150 ure 4, the two pistons are shown in their normal relationship at the left end of the cylinder. In Figure 5, a relative separation of the pistons has been effected, thereby causing an engagement of the tube into which the claw has been inserted. In Figure 6, the pistons are shown at the end of the withdrawal operation, the tube still being engaged, and the outlet port 68 having just been uncovered. In Figure 7, the auxiliary piston has caught up with the main piston, thereby causing a lrelease of the engaged tube.

In actual operation, thev operator flrst supports the cylinder upon a cable 72, as indicated in Figure 1, this cable engaging with a supporting plate '73 which is secured to a strap '74 extending completely around the cylinder. The wedge member 21 is adjusted so that the outward radial movement of the teeth 13 will be just suii'icient to engage rmly with the tube to be withdrawn. This adjustment also compensates for varying diameters of tubes. With the teeth in retracted position (i. e., with the rod 19 positioned forwardly to its full extent) the forward operative end of the device (i. e., the claw) is inserted into the tube to be withdrawn. The extent of this insertion is adjusted 'by xing the length of the sheath 48 to the desired amount. Inasmuch as the tubes mounted in any one tube sheet are identical in character and size, an initial adjustment of the sheath 48 and of the wedge 21 will render the device usable without further adjustment in the withdrawal of all the tubes from that particular tube sheet.

The claw having been inserted to the proper extent, there is nothing left for the operator to do except to manipulate the control handle 63 so as to set it into the position of Figure 2. By doing this, he enables the operating fluid automatically to cause the piston movements hereinbefore described to take place in rapid and automatic succession. At the risk of repetition, it is pointed out that the operating iiuid causes rst a piston separation which effects tube engagement; then a joint piston movement which eiects withdrawal of the claw and the engaged tube with respect to the tube sheet; and iinally a reverse relative piston movement which eiects a disengagement of the tube by the claw. All of the foregoing takes place within a second or so, sometimes within even a shorter time.

The operator then withdraws the tool from the tube that has been pulled; throws the valve into the reverse position to eect a return of the pistons to initial relationship; and proceeds at once to repeat the entire procedure with the next tube that is to be pulled.

It will be understood that the broader phases of my invention are independent of the speciiic structural details herein described and illustrated in connection with one embodiment. For example, while I have shown a by-pass 66 for accomplishing an unbalancing of fluid pressure on opposite sides of the pistons, this same general effect might be produced in other ways. One convenient manner of doing this is to provide a small bore through the piston 29, whereby the operating fluid, when interposed between the pistons, has an opportunity slowly but comulatively to pass through this bore to the opposite or left hand side of the piston 29. The reason why the by-pass 66 is preferable is that it is accurately controllable by means of the needle valve handle 75. By adjustments of this handle, the speed with which the tube withdrawing operation follows upon the tube engaging step may be accurately controlled and adjusted.

The type of iiuid controlling valve may also be modied to comply with different requirements,al though the construction illustrated has proven to be satisfactory. While I have shown the exhaust outlet 62 provided in a projection 76 which rests in a block 77 carried by the strap 74, any other convenient location of the exhaust opening may be provided for. In the illustrated embodiment, While the deails have not been illustrated, the exhaust opening 62 registers with a bore provided in the block 77 so that the exhausting fluid is directed downwardly through the block 77 and toward the iioor when the device is used. Similarly, the exhaust opening 68 may be provided, if desired, in the bottom Wall of the cylinder so that the outward passage of fluid through this opening will be directed toward the iioor when the device is used.

While I have shown a group of four teeth 13 as constituting the claw of the device, a smaller or greater number of teeth may be employed, if desired, and it will be understood that the teeth may be constructed in any convenient or desired manner, depending upon the particular nature of the tube engagement that is sought to be accomplished thereby.

In general, it will be obvious that changes in the details herein described and illustrated for the purpose of explaining the nature of my invention may be made by those skilled in the art, Without departing from the spirit and scope of the invention as expressed in the appended claims. It is, therefore, intended that these details be interpreted as illustrative, and not in a hunting sense.

Having thus described my invention, and i1- lustrated its use, what I claim as new and desire to secure by Letters Patent is- 1. In a device for pulling a tube from a tube sheet, a claw insertable into the tube, and a single exteriorly controllable means for automatically eiTecting in succession, a tube engagement, a withdrawal of the engaged tube, and a disengagement of the tube while the tube is in withdrawn position.

2. In a device for pulling a tube from a tube sheet, a claw insertable into the tube, means for operatively interposing an expansible medium between the tube sheet and the claw for drawing the latter out with respect to the tube sheet, and automatic means for initially causing engagement of the claw with the -tube and for subsequently causing disengagement of the withdrawn tube while the latter is in withdrawn position.

3. In a device for pulling a tube from a tube sheet, a claw insertable into the tube, va main movable member controlling the withdrawal of said claw with respect to the tube sheet, an auxiliary member mounted for relative movement with respect to said main member, means operable by relative movement of said members for controlling the tube engaging operation of said claw, and means for automatically producing, in succession, a relative movement of said members for eilecting engagement of the tube by said claw, a movement of the main member for withdrawing the engaged tube from the tube sheet, and a reverse relative movement of said members for causing disengagement of the with- ;lrawn tube while the latter is in withdrawn posi- 4. In a device for pulling a tube from a tube sheet, a claw'insertable into the tube, a cylinder,

a main piston in said cylinder for controlling the withdrawal of the claw with respect to the tube sheet, an auxiliary piston mounted in the cylinder for relative movement with respect to the main piston, means operable by relative movement of said pistons for controlling the tube engaging operation of said claw, means for effecting a tube engagement by said claw, and means for enabling a uid automatically to cause rst a main piston movement Vto effect tube withdrawal and then a relative piston movement to effect tube disengagement while the tube is in withdrawn position.

5. In a device for pulling a tube from a tube sheet, a claw insertable into the tube, a cylinder, a main piston in said cylinder for controlling the Withdrawal of the claw wlth'respect to the tube sheet, an auxiliary piston mounted in the cylinder for relative movement with respect to the main piston, means operable by relative movement of said pistons for controlling the' tube engaging operation of said claw, and means for enabling a fluid automatically to cause rst a relative piston movement to eiect tube engagement, then a main piston movement to effect tube withdrawal, and finally a reverse relative piston movementrto effect tube disengagement while the tube is in withdrawn position.

6. In a device for pulling a tube from a tube sheet, a claw insertable into the tube, a cylinder, a main piston in said cylinder for controlling the withdrawal of the claw lwith respect to the tube sheet, an auxiliary piston mounted in the cylinder for relative movement with respect to the main piston, means operable by relative movement of said pistons for controlling the tube engaging operation of said claw, means for interposing a fluid between the pistons to cause a relative piston movement to effect tube engagement, and means for unbalancing the pressures on the outermost piston faces to cause a main piston movement, thereby effecting withdrawal of the engaged tube.

'7. In a device for pulling a tube from a tube sheet, a claw insertable into the tube, a cylinder, a main piston in said cylinder for controlling the withdrawal of the claw with respect to the tube sheet,A an auxiliary piston mounted in the cylinder for relative movement with respect to the main piston, means operable by relative movement of said pistons for controlling the tube engaging operation of said claw, means for interposing a uid between the pistons to cause a relative piston movement to elect tube engagement, and slower-functioning means for introducing said uid also to the outer face of one of the pistons to cause a main piston movement, thereby effecting withdrawal 01 the engaged tube.

8. In a device for pulling a tube from a tube sheet, a claw insertable into the tube, a cylinder, a main piston in said cylinder for controlling the withdrawal of the claw with respect to the tube sheet, an auxiliary piston mounted in the cylinder for relative movement with respect to the main piston. means operable by relative movement of said pistons for controlling the tube engaging operation of said claw, means for interposing a fluid bei veen the pistons to cause a relative piston movement to effect tube engagement. and a by-pass for introducing said uid also to the outer face of one of the pistons to cause a main piston movement, thereby effecting withdrawal of the engaged tube.

9. In a device for pulling a tube from a tube sheet, a claw insertable into the tube, a cylinder, a main piston in said cylinder for controlling the withdrawal of the claw with respect to the tube sheet, an auxiliary piston mounted in the cylinder for relative movement with respect to the` main piston, means operable by relative movement of said pistons for controlling the tube engaging operation of said claw, means for interposing a fluid between the pistons to cause a relative piston movement to effect tube engagement, and means for unbalancing the pressures on the outermost piston faces to cause a main piston movement, thereby eiecting withdrawal of the engaged tube, and a regulator for the last-named means to control the speed of eiectiveness of said unbalancing means.

10. In a device for pulling a tube from a tube sheet, a claw insertable into the tube, a cylinder, a main piston in said cylinder for controlling the withdrawal of the claw with respect to the tube sheet, an auxiliary piston mounted in the cylinder for relative movement with respect to the main piston, means movable with the main piston for engaging the auxiliary piston after a predetermined relative piston movement, means operable by relative piston movement for controlling the tube engaging operation of said claw, and means for enabling a uid automatically to cause first a relative piston movement to effect tube engagement, then a joint piston movement to effect tube withdrawal, and nally a reverse relative piston movement to effect tube disengagement while the tube is in withdrawn position.

11. In a device for pulling a tube from a tube sheet, a claw insertible into the tube, a cylinder, a pair of pistons in the cylinder, means operable by separation and juxtaposition of the pistons for causing, respectively, tube engagement and disengagement by said claw, means operable by joint movement of the pistons for controlling the withdrawal of the claw with respect to the tube sheet, and means for enabling a fluid automatically to cause first a separation of pistons near one end of the cylinder, then a joint piston move ment toward the other end of the cylinder, and finally a juxtaposition of pistons at said other end of the cylinder.

12. In a device for pulling a tube from a tube sheet, a claw insertable into the tube, a cylinder having a uid inlet near one end, a main piston and an auxiliary piston in the cylinder normally arranged with the auxiliary piston at one end of the cylinder and with the inlet between the pistons, means movable with the main piston for engaging the auxiliary piston after a predetermined piston separation, a fluid outlet positioned so as to be uncovered only after a predetermined joint piston movement, means operable by separation and juxtaposition of the pistons for, respectively, effecting engagement and disengagement of the tube by said claw, and means operable by joint piston movement for effecting withdrawal of the claw relative to the tube sheet.