US3352213A

US3352213A - Expansible reciprocating piston

Info

Publication number: US3352213A
Application number: US433309A
Authority: US
Inventors: Raymond J Karol
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-02-17
Filing date: 1965-02-17
Publication date: 1967-11-14
Anticipated expiration: 1984-11-14

Description

Nov. 14, 1967 R. J. KAROL 3,352,213

EXPANSIBLE RECIPROCATING PISTON Filed Feb. 17, 1965 2 Sheets-Sheet 1 Fig.

Fig.2

INVENTOR.

RAYMOND J. KAROL Nov. 14, 1967 Filed Feb. 17, 1965 R. J. KAROL EXPANSIBLE RECIPROCATING PISTON 2 sheets sheet 2 Fig.6

INVENTOR. 45 RAYMOND J. KAI-POL United States Patent 3,352,213 EXPANSIBLE RECIPROCATING PISTON Raymond J. Karol, 13616 Lake Shore BlvtL, Cleveland, Ohio 44110 Filed Feb. 17, 1965, Ser. No. 433,309 5 Claims. (Cl. 92-204) My invention relates to reciprocating pistons and more particularly to expansible reciprocating pistons.

My invention may be embodied in pistons as originally manufactured or in pistons already in use. In the case of embodying my invention in pistons already in use, my invention comprises the steps of reshaping some of the used parts and then combining the reshaped parts with some new parts to make my new expansible piston.

An object of my invention is to convert a non expansible used piston over to that of an expansible piston.

Another object is the provision of an expansible piston with simple, easy, positive and accurate means to increase the diameter as desired or necessary.

Another object is to convert a used piston over to that of my expansible piston while still maintaining the same axial length of the piston as before, whereby the volumetric clearance in the cylinder remains at the original specification and the volumetric efli-ciency continues unchanged.

Another object is to effect such conversion, whereby the converted piston maintains the same dimensions and position relative to the original placement of the cylinder counterbore.

Other objects of my invention may be briefly classified as follows:

To extend indefinitely the useful life of an existing piston of any size or construction;

To replace a broken or damaged piston with one containing unlimited useful life;

To eliminate excessive clearance between piston and cylinder bore due to wearing on piston, cylinder wall, or both, causing a knock or slap through lateral motion;

To prevent lateral movement or wobbling motion of piston rod in packing box, thereby extending life of rod seals, while maintaining better sealing and preventing piston rod from becoming scored or gouged by contacting sides of packing box;

To overcome necessity of installing piston rings With greater radial thickness to prevent rings from leaving grooves and entering space between piston and cylinder wall, resulting in damage to piston and cylinder;

To eliminate piston rings with excessive radial thickness which accelerates wear through excessive tension on themselves and on the cylinder wall;

To continue using existing piston when cylinder is rebored by expanding piston to suit larger diameter of rebored cylinder;

To provide an adjustable plug piston with near-sealing qualities without sealing rings or piston packing which has proved practical and desirable due to low wearing rate in higher pressures;

To provide an adjustable piston to accommodate sealing rings or commercially obtained packing installed in the conventional manner;

To avoid piston replacement when worn to extent of not functioning properly;

To construct an expansible piston with a wide range of adjustment to compensate for wear of the piston and cylinder parts so as to obtain alignment of other machineparts and remove the possibility of damage or failure of associated parts due to excessive lateral movement or wobbling of the piston;

To construct an expansible piston with a wide range of adjustment obtainable while at the same time maintaining essentially the original volumetric clearance and efliciency;

To construct an expansible piston which at every expanded position will be held in solid axial compression "under tension with its outer wear member supported in a positive radial location;

To construct an expansible piston which can be adjusted before and after wear to accommodate commercially available piston rings and/ or packings;

To construct an expansible plug piston which can be used without piston rings or packings and obtain near sealing and superior performance in some applications;

To provide a construction of an expansible piston that can be applied easily to many existing piston constructions.

Other objects and a fuller understanding of the invention may be had by referring to the following description and claims in conjunction with the accompanying drawings, in which:

FIGURE 1 is a cross-sectional view of an expansible piston embodying the features of my invention, the view showing the relationship of the parts as originally installed and illustrating the situation Where my invention is embodied in a piston as originally manufactured;

FIGURE 2 is a cross-sectional view similar to that of FIGURE 1, the view showing the relationship of the parts after the piston has been adjusted to compensate for cylinder wear;

FIGURE 3 is a semicircular plan view of FIGURE 2, the right half showing the relationship of the parts with the clamping member removed;

FIGURE 4 is a semicircular plan View of an existing piston which may be converted over to an expansible piston embodying the features of my invention, the right half showing the relationship of the parts with the clamping member removed;

FIGURE 5 is a cross-sectional view of the piston in FIGURE 4, taken along the line 5-5 thereof;

FIGURE 6 is a fragmentary View of the piston only shown in FIGURE 5 with my invention embodied therein, the view showing my expansible piston as it will appear when originally installed;

FIGURE 7 is a view similar to FIGURE 6, the view showing the relationship of the parts after the piston has been used and after an adjustment has been made therein to compensate for cylinder wear;

FIGURE 8 is an enlarged fragmentary plan view of my expansible piston in FIGURE 6 with the clamping member removed, the view showing that portion of my piston which is comparable to the piston in FIGURE 4 through which the line 5-5 passes; and

FIGURES 9 and 10 are enlarged fragmentary cross sectional views of the right-hand side of FIGURES 5 and 6 respectively.

With reference to FIGURES 1 to 3 of the drawings, my invention is illustrated as representing the situation Where it is embodied in a piston as originally manufactured, as distinguished from the situation Where it is incorporated in a used piston, the latter being illustrated by the FIG- URES 4 to 10. In FIGURE 1, my expansible piston shows the relationship of the parts as they would appear when first being installed in a cylinder. Preferably, the parts of my expansible piston are manufactured to specific dimensions so that when the piston is mounted into a cylinder it makes a good slidable fit therewith without any adjustments. The adjustments come later after cylinder Wears, as shown in FIGURE 2.

Generally my expansible piston comprises a centrally disposed piston support body 10, a clamping member 11, an expansible Wear band 12 and an axially movable annu port body has first and second opposed

end portions

18 and 19 and an axially extending outer body surface 20 radially spaced inwardly from the cylinder wall or bore which is identified by the reference character 21. The first end portion 18 ofthe piston support body 10 has an abutment support flange 22'with an abutment support flange surface 23 extending in a direction radially from the axially extending outer body surface 20 and terminating within the limits of the cylinder wall 21.

The second end portion 19 of the piston support body 10 has the clamping member 11 detachably'connected thereto by the nut 15. As illustrated, the clamping member 11, upon being connected to the secondend portion 19 of the piston support body 10 comprises an abutment clamping flange having an abutment clamping flange surface26 extending in a direction radially from the axially extending outer body surface 20 and terminating within the limits of the cylinder wall 21. The abutment clamping flange surface 26 and the abutment support flange surface 23 oppose and face each other.

The expansible wear band 12 has an outer substantially cylindrical surface 27 for slidably engaging the cylinder wall or bore 21 and an inner surface cam means 28 radie ally spaced from and annularly disposed about the exially extending outer body surface 20*. of the piston support body 10. The exansible wear band 12 preferably comprises a split band (see FIGURE 3) whereby it may be expanded relative to the cylinder wall 21. The wear band 12 comprises first and second abutmeunt opposed

end surfaces

29 and 30 which are respectively clamped between the abutment support flange surface 23 and the abutment clamping flange surface 26.

The axially movable annular cam member 13 is disposed between the axially extending outer body surface 20 of the piston support body 10 and the inner. surface cam means 28. The nut 15, upon connecting the clamping member 11 to the second end portion 19 of the piston support body 10, axially forces or moves the cam member 13 relative to the inner surface cam means 28 toward the abutment support flange surface 23 and thereby expands the wear band 12 to make a good slidable fit with the cylinder wall 21. In tightening the nut 15, the first and. second abutment opposed

end surfaces

29 and 30 of the wear band 12 are clamped respectively between the abut ment support flange surface 23 and the abutment clamping flange surface 26. The first and second abutment opposed

end surfaces

29 and 30 of the wear band 12, upon being clamped, limit the axial extent to which the clamping member 11 may force the axially movable annular cam member 13 against the inner surface cam means 28 for arresting the expansion of the expansible wear band relative to the cylinder wall.

FIGURE 1 shows the relationship of the parts of my expansible piston as they would appear when first installed in the cylinder. In practice, the parts are manufuactured to specific dimensions in relation to the diameter of the piston bore, so that when the piston is mounted within the cylinder bore it makes a good slidable fit therewith without any adjustments. By manufacturing the parts to specific dimensions, it is to be noted that the abutment clamping flange surface 26 constitutes a fixed surface driving means for positively driving the cam member 13 axially a fixed amount relative to the inner surface cam means 28 for expanding the expansible wear band 12. In assembly, due to the specific dimensions, there is a clearance indicated by the reference character 31 between the second opposed end portion 19 of the piston support body 10 and the clamping member 11. The clearance 31 provides positive assurance that the expansible wear band 12 is solidly clamped under tension between the abutment clamping flange surface 26 and the abutment support flange suruface 23 when the nut is turned down tight.

With the clearance 31, the assembly is held solidly together under tension so that there is no tendency for the assembly to become loose through continuous use. The piston of FIGURE 1 may be operated without the usual piston rings or packing, in which case the expansible wear band 12 constitutes an expansible plug piston with nearsealing qualities.

FIGURE 2 illustrates the situation where the cylinder bore has become worn through use to a larger diameter indicated by the reference character 34 and where my expansible piston ,has been adjusted to slidably fit the increased diameter. In my invention, the adjustment is preferably made by using one or more circular shims indicated by the reference character 35. The shims 35 increase the extent to which the clamping member 11 may positively force the axially movable annular cam member 13 against the inner surface cam means 28 of the expansi-.

ble wear band 12 for increasing the expansion thereof relative to the cylinder bor 34. In FIGUREI, the abutment clamping flange surface 26 comprises a fixed surface driving means for positively driving the cam member 13 axially a fixed amount relative to the inner surface cam means 28 for expanding the expansible wear band 12...

In FIGUREZ, the abutment clamping flange surface 26 and the shims 35 comprise an adjustably fixed surface driving means. In other words, the surface means is adjustably fixed by the shims 35.

In my invention, the expansible wear band 12 may be continuously used and adjustably expanded at intervals until the advanced end surface 36 of the axially movable annular cam member 13 hits or engages the abutment support flange surface 23, indicating that the expansible band is in need of replacement, at which time a new expansible wear band may be installed in its stead to fit the increased diameter of the cylinder bore.

As. pointed out before, the FIGURES 4 to 10 illustrate a situation where a used piston is converted over to my expansible piston. The FIGURES 4 and 5 show a used piston which may be so converted, although it is to be understood that my invention may be applied to used pistons of all types and construction and is not limited to the type illustrated. In FIGURES 4 and 5, the illustrated used piston comprises a piston supportbody 40 detachably connected to a piston rod 41 by a nut 42. The piston rod 41 is sealed by a suitable packing gland or box 43. As best seen in FIGURE 4, the piston support body 40 has a plurality of radially extending bosses 47, which in the trade are sometimes referred to as spokes. These bosses are positioned at annularly spaced intervals about the piston support body 40 and they each have an axially extending outer face or surface 44 which terminates into an annular abutment support flange 45 having an annular abutment support flange surface 46. The annular abut ment support flange 45 including the adjacent region constitutes a first end portion 38 (see FIGURE 9) of the piston support body 40 and functionally it is comparable to the first end portion 18 in FIGURES 1 and 2. The outer faces or surfaces 44 of the bosses 47 comprise segments of a cylindrical surface and functionally they are comparable to the axially extending outer body surface 20 of the piston support body in FIGURES 1 and 2. The upper portion of the bosses 47 constitute a second end portion 39 of the piston support body 40 and functionally it is comparable to the second end portion 19 in FIGURES 1- and 2.

Surrounding the outer segmental cylindricalsurfaces 44 of the bosses 47 is a non-expansible circular band 48 provided with

piston rings

49 and 50. As illustrated, the circular band 48 is held in position by a clamping member 54 which is detachably connected to the bosses 47 of the piston support body 40 byaseries of nuts and bolts 55 or any other suitable means. The clamping member 54 comprises an abutment clamping flange having an abutment clamping flange surface 57 extending in a direction radially from the axially extending outer segmental surfaces 44 and terminating within the limits of the cylinder bore. The abutment clamping flange surface 57 opposes the abutment support flange surface 46. As illustrated, the circular band 48 is provided with first and second abutment opposed end surfaces 53 and 56 which are respectively clamped between the abutment support flange surface 46 and the abutment clamping flange surface 57. There is a small clearance 61 between the upper surface of the bosses 47 of the piston support body and the abutment clamping flange surface 57 so that the circular band is solidly clamped in position under tension, whereby the parts will not become loose in operation.

In practice, the piston ring 50 is positioned to partially overlap the edge of the counterbore 51 at the end of the piston stroke so that when the cylinder wears, it will wear all the way up to the counterbore 51, otherwise the wear would leave an inside circular shoulder next adjacent to the counterbore. The

rings

49 and 50 are illustrated as having been worn thin, being a condition found in practice in which case there is a possibility that they might leave the piston grooves and enter the space between the piston and the cylinder wall 52. As will be seen later, my expansible piston will prevent such a condition. In FIGURE 5, the clearance between the piston and cylinder wall 52 is shown all on the right-hand side as would be the case where the cylinder is mounted in a horizontal position.

In converting the used piston of FIGURES 4 and 5 over to that of my invention, attention is directed to FIGURES 6 to 10. All the existing parts are retained. The circular band 48, however, is reshaped by machining or othei'wise providing on the inside surface thereof a plurality of inside notches or key ways 58 opposite the radially extending bosses 47 (see FIGURE 8). The circular band 48 is also cut into to make it a split band for rendering it expansible or it may be a new band with the same construction. The notches each terminate into an inner surface cam means 59, Mounted in each of the notches is an axially movable cam element 60 (this is new) which engages the inner surface cam means 59. The abutment clamping flange surface 57 of the clamping member 54, upon the tightening of the nuts 55, drives the cam elements 60 axially against the inner surface cam means 59 for expanding the expansible band 48 into slidable engagement with the worn cylinder bore 52 (see FIGURE 6). Functionally, the arrangement of the parts in FIG- URE 6 which now comprise the converted piston is substaantilly the same as that illustrated and described with reference to FIGURES 1 to 3. The relationship of the parts is such that when the converted piston is mounted within the cylinder bore 52 it makes a good slidable fit therewith without any adjustments, as shown in FIGURE 6. The description with respect to FIGURES l to 3 apply equally well to the construction and operation of the converted piston in FIGURES 6 to 10.

The abutment clamping flange surface 57 constitutes a fixed surface driving means for positively driving the cam elements 60 axially a fixed amount relative to the inner surface cam means 59 for expanding the expansible band 48. As the nut and bolts 55 are tightened, the abutment clamping flange surface 57 upon engaging the abutment end surface 53 of the expansible band 48 is arrested against further axial movement. Thus, the band 48 limits the extent to which it may be expanded. In construction, the parts are so dimensional that the expansible band 48 makes a good sliding engagement with the cylinder bore at the point that the abutment clamping flange surface 57 is arrested.

The FIGURE 7 illustrates the situation where the cylinder bore has become worn, through use of my converted expansible piston, to a larger diameter now indicated by the reference character 62. The FIGURE 7 also shows the situation Where my converted expansible piston has been adjusted to slidably fit the increased diameter. As illustrated before with respect to FIGURE 2, the adjustment is preferably made by using one or more shims 63 disposed between the cam elements 60 and the abutment clamping flange surface 57 of the clamping member 54. In FIGURE 7, the abutment clamping flange surface 57 and the shims 63 comprise an adjustably fixed surface driving means the same as that performed by the abutment clamping flange surface 26 and the shims 35 in FIGURE 2. The shims 63 increase the extent to which the clamping member 54 may positively force the axially movable cam elements 60 against the inner surface cam means 59 of the expansible band 48 for increasing the expansion thereof relative to the cylinder bore. Since the expansible band 48 may be readily adjusted to make a good slidable fit with the cylinder bore, the piston rings need not be excessively thick in a radial direction as would be the case where there is considerable clearance between the piston and the cylinder bore. Thus, the possibility of the piston rings leaving their grooves is eliminated with my invention. In addition, it is to be noted that at every expanded position of the expansible band, as affected by the insertion of additional shims, the band is held in solid axial compression. This construction thus gives positive assurance that the original volumetric clearance and efliciency is maintained, because the axial effective length of my converted piston is the same as that which existed before the conversion was made. Furthermore, all the other objects which I have listed herein are fully achieved by my expansible piston construction.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to Without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. An expansible piston disposed for connection to a piston rod and for reciprocal movements within a cylinder bore, said piston comprising a centrally disposed piston support body disposed for connection to said piston rod, said piston support body having first and second opposed end portions and an axially extending outer body surface radially spaced inwardly from said cylinder bore, said first end portion of said piston support body having abutment support flange surface means extending radially from said outer body surface of said piston support body and terminating within the limits of said cylinder bore, said second end portion of said piston support body having clamping means including clamping member means, connecting means for detachably connecting said clamping member means to said second end portion of said piston support body, said clamping member means including abutment clamping flange surface means radially extending from said outer body surface of said piston support body and terminating within the limits of said cylinder bore, said clamping member means having a laterally extending surface spaced from and disposed in face-toface relation to said second end portion of said piston support body to provide a clearance space therebetween, said abutment clamping flange surface means and said abutment support flange surface means opposing and facing each other, expansible band means having an outer substantially cylindrical surface for slidably engaging said cylinder bore and comprising a first band portion, a second band portion, and an intermediate band portion between said first and second band portions, said intermediate band portion having inner surface cam means radially spaced from and annularly disposed about said outer body surface of said piston support body, said first and second band portions respectively of said band means having first and second abutment opposed end surfaces respectively clamped between said abutment support flange surface means and said abutment clamping flange surface means, said inner surface cam means having first and second terminating ends axially spaced respectively from said abutment support flange surface means and said abutment clamping flange surface means and axially movable cam means disposed between said outer body surface of said piston support body and said inner surface cam means for expanding said band means relative to said cylinder bore, said abutment clamping flange surface means comprising fixed surface driving means engaging said cam means and forcibly driving said cam means against said innersurface cam means of said band means, said connection means upon connecting said clamping member means to said second end portion of said piston support body moving said laterally extending surface toward said second end portion of said piston support body and also axially moving said cam means relative to said inner surface cam means toward said abutment support flange surface means and thereby expanding said band means, said first and second abutment opposed end surfaces of said band means upon being clamped between said abutment support flange surface means and said abutment clamping flange surface means arresting the aixal movement of said laterally extending surface before it engages said second end portion of said piston support body to thereby maintain said clearance space, whereby said expandable band means is solidly clamped between said abutment support flange surface means and said abutment clamping flange surface means, said first and second abutment opposed end surfaces of said band means upon being clamped between said abutment support flange surface means and said abutment clamping flange surface means also limiting the axial extent to which said clamping member means may force said cam means against said inner surface cam means of said band means for arresting the expansion of said band means relative to said cylinder bore.

2. The structure as claimed in claim 1, wherein said fixed surface driving means includes shim means.

3. The structure as claimed in claim 1, wherein said axially movable cam means comprises a circular hollow body and said expansible band means including said first, second and intermediate band portions and said inner surface cam means comprise an integral one piece member.

4. An expansible piston disposed for connection to a piston rod and for reciprocal movements Within a cylinder bore, said piston comprising a centrally disposed piston support body disposed for connection to said piston rod, said support piston body having first and second opposed end portions and an axially extending outer body surface radially spaced inwardly from said cylinder bore, said first end portion of said piston support body having abutment support flange surface means extending radially from said outer body surface of said piston support body and terminating within the limits of said cylinder bore,

said second end portion of said piston support body hav- 7 ing clamping means including clamping member means, connection means for detachably connecting said clamping member means to said second end portion of said piston support body, said clamping member means including abutment clamping flange surface means radially extending from said outer body surface of said piston support body and terminating within the limits of said cylinder bore, said clamping member means having a laterally extending surfacespaced from and disposed in face-to-face relation to said second end portion of said piston support body to providea clearance space therebetween, said abutment clamping flange surface means and said abutment support flange surface means opposing and facing each other, expansible band means having an outer substantially cylindrical surface for slidably enment opposed end surfaces respectively clamped between said abutment support flange surface means and said abutmentclamping flange surface means, said inner surface cam means having first and second terminating ends axially spaced respectively from said abutment support flange surface means and said abutment clamping flange surface means and axially movable cam means disposed between said outer body surface of said piston support body and said inner surface cam means for expanding said band means relative to said cylinder bore, said axially movable cam means including a plurality axially movable cam element means disposed for axial engagement respectively against said plurality of inner surface cam means, said abutment clamping flange surface means comprising fixed surface driving means engaging said plurality of cam element means and forcibly driving said plurality of cam element means against said plurality of inner surface cam means of said band means, said connection means upon connecting said clamping member means to said second end portion of said piston support-body moving said laterally extending surface toward said second end portion of said piston support body and also axially moving said plurality of cam element means relative to said plurality of inner surface cam means toward said abutment support flange surface means and thereby expanding said band means, said first and second abutment opposed, end surfaces of said band means upon being clamped between said abutment support flange surface means and said abutment clamping flange surface means arresting the axial movement of said laterally extending surface before it engages said second end portion of said piston support body to thereby maintain said clearance space, whereby said expandable band means is solidly clamped between said abutment support flange surface means and said abutment clamping flange surface means, said first and second abutment opposed end surfaces of said band means upon being clamped between said abutment support flange surface means and said abutment clamping flange surface means also limiting the axial extent to which said clamping member means may force said plurality of cam element means against said plurality of inner surface cam means of said band means for arresting the expansion of said band means relative to said cylinder bore.

5. The structure as claimed in claim 4, wherein said fixed surface driving means includes shim means.

References Cited UNITED STATES PATENTS 114,427 5/1871 Estes 92207 751,252 2/1904 Boop 92207 912,460 2/1909 Frisk 92207 1,054,345 2/1913 Frank 92207 1,140,948 5/1915 Carroll 92207 1,264,789 4/1918 Haswell 92207 FOREIGN PATENTS 417,466 10/1934 Great Britain.

MARTIN P. SCHWADRON, Primary Examiner.

G. N. BAUM, Assistant Examiner.

Claims

1. AN EXPANSIBLE PISTON DISPOSED FOR CONNECTION TO A PISTON ROD FOR RECIPROCAL MOVEMENTS WITHIN A CYLINDER BORE, SAID PISTON COMPRISING A CENTRALLY DISPOSED PISTON SUPPORT BODY DISPOSED FOR CONNECTION TO SAID PISTON ROD, SAID PISTON SUPPORT BODY HAVING FIRST AND SECOND OPPOSED END PORTIONS AND AN AXIALLY EXTENDING OUTER BODY SURFACE RADIALLY SPACED INWARDLY FROM SAID CYLINDER BORE, SAID FIRST END PORTION OF SAID PISTON SUPPORT BODY HAVING ABUTMENT SUPPORT FLANGE SURFACE MEANS EXTENDING RADIALLY FROM SAID OUTER BODY SURFACE OF SAID PISTON SUPPORT BODY AND TERMINATING WITHIN THE LIMITS OF SAID CYLINDER BORE, SAID SECOND END PORTION OF SAID PISTON SUPPORT BODY HAVING CLAMPING MEANS INCLUDING CLAMPING MEMBER MEANS, CONNECTING MEANS FOR DETACHABLY CONNECTING SAID CLAMPING MEMBER MEANS TO SAID SECOND END PORTION OF SAID PISTON SUPPORT BODY, SAID CLAMPING MEMBER MEANS INCLUDING ABUTMENT CLAMPING FLANGE SURFACE MEANS RADIALLY EXENDING FROM SAID OUTER BODY SURFACE OF SAID PISTON SUPPORT BODY AND TERMINATING WITHIN THE LIMITS OF SAID CYLINDER BORE, SAID CLAMPING MEMBER MEANS HAVING A LATERALLY EXTENDING SURFACE SPACED FROM AND DISPOSED IN FACE-TOFACE RELATION TO SAID SECOND END PORTION OF SAID PISTON SUPPORT BODY TO PROVIDE A CLEARANCE SPACE THEREBETWEEN, SAID ABUTMENT CLAMPING FLANGE SURFACE MEANS AND SAID ABUTMENT SUPPORT FLANGE SURFACE MEANS OPPOSING AND FACING EACH OTHER, EXPANSIBLE BAND MEANS HAVING AN OUTER SUBSTANTIALLY CYLINDRICAL SURFACE FOR SLIDABLY ENGAGING SAID CYLINDER BORE AND COMPRISING A FIRST BAND PORTION, A SECOND BAND PORTION, AND AN INTERMEDIATE BAND PORTION BETWEEN SAID FIRST AND SECOND BAND PORTIONS, SAID INTERMEDIATE BAND PORTION HAVING INNER SURFACE CAM MEANS RADIALLY SPACED FROM AND ANNULARLY DISPOSED ABOUT SAID OUTER BODY SURFACE OF SAID PISTON SUPPORT BODY, SAID FIRST AND SECOND BAND PORTIONS RESPECTIVELY OF SAID BAND MEANS HAVING FIRST AND SECOND ABUTMENT OPPOSED END SURFACES RESPECTIVELY CLAMPED BETWEEN SAID ABUTMENT SUPPORT FLANGE SURFACE MEANS AND SAID ABUTMENT CLAMPING FLANGE SURFACE MEANS, SAID INNER SURFACE CAM MEANS HAVING FIRST AND SECOND TERMINATING ENDS AXIALLY SPACED RESPECTIVELY FROM SAID ABUTMENT SUPPORT FLANGE SURFACE MEANS AND SAID ABUTMENT CLAMPING FLANGE SURFACE MEANS AND AXIALLY MOVABLE CAM MEANS DISPOSED BETWEEN SAID OUTER BODY SURFACE OF SAID PISTON SUPPORT BODY AND SAID INNER SURFACE CAM MEANS FOR EXPANDING SAID BAND MEANS RELATIVE TO SAID CYLINDER BORE, SAID ABUTMENT CLAMPING FLANGE SURFACE MEANS COMPRISING FIXED SURFACE DRIVING MEANS ENGAGING SAID CAM MEANS AND FORCIBLY DRIVING SAID CAM MEANS AGAINST SAID INNER SURFACE CAM MEANS OF SAID BAND MEANS, SAID CONNECTION MEANS UPON CONNECTING SAID CLAMPING MEMBER MEANS TO SAID SECOND END PORTION OF SAID PISTON SUPPORT BODY MOVING SAID LATERALLY EXTENDING SURFACE TOWARD SAID SECOND END PORTION OF SAID PISTON SUPPORT BODY AND ALSO AXIALLY MOVING SAID CAM MEANS RELATIVE TO SAID INNER SURFACE CAM MEANS TOWARD SAID ABUTMENT SUPPORT FLANGE SURFACE MEANS AND THEREBY EXPANDING SAID BAND MEANS, SAID FIRST AND SECOND ABUTMENT OPPOSED END SURFACES OF SAND BAND MEANS UPON BEING CLAMPED BETWEEN SAID ABUTMENT SUPPORT FLANGE SURFACE MEANS AND SAID ABUTMENT CLAMPING FLANGE SURFACE MEANS ARRESTING THE AXIAL MOVEMENT OF SAID LATERALLY EXTENDING SURFACE BEFORE IT ENGAGES SAID SECOND END PORTION OF SAID PISTON SUPPORT BODY TO THEREBY MAINTAIN SAID CLEARENCE SPACE, WHEREBY SAID EXPANDABLE BAND MEANS IS SOLIDLY CLAMPED BETWEEN SAID ABUTMENT SUPPORT FLANGE SURFACE MEANS AND SAID ABUTMENT CLAMPING FLANGE SURFACE OF SAID BAND MEANS UPON ABUTMENT OPPOSED END SURFACE MEANS, SAID FIRST AND SECOND BEING CLAMPED BETWEEN SAID ABUTMENT SUPPORT FLANGE SURFACE MEANS AND SAID ABUTMENT CLAMPING FLANGE SURFACE MEANS ALSO LIMITING THE AXIAL EXTENT TO WHICH SAID CLAMPING MEMBER MEANS MAY FORCE SAID CAM MEANS AGAINST SAID INNER SURFACE CAM MEANS OF SAID BAND MEANS FOR ARRESTING THE EXPANSION OF SAID BAND MEANS RELATIVE TO SAID CYLINDER BORE.