US2986376A - Strap tensioning tool - Google Patents

Description

y 1961 K. A. FALCK-PEDERSEN 2,986,376

STRAP TENSIONING TOOL U WW, MW. @NWN m 06 1 w fi a a. T MM m e y M m .fiw w 4 n I K Q9 w Q QN w 5% m m S w m y 1961 K. A. FALCK-PEDERSEN 2,986,376

STRAP TENSIONING TOOL 4 Sheets-Sheet 2 Filed Sept. 24, 1956 INVENTOR. 'eZZ Fzlo/c-Pedersem y 1961 K. A. FALCK-PEDERSEN 2,986,376

STRAP TENSIONING TOOL 4 Sheets-Sheet 3 Filed Sept. 24, 1956 INVENTOR. /c-Pederaem Jgeu Clg zlc y 30, 1951 K. A. FALCK-PEDERSEN 2,986,376

STRAP TENSIONING TOOL 4 Sheets-Sheet 4 Filed Sept. 24, 1956 INVENTOR. @Falck-Peafizvtsen United States Fatent G STRAP TENSIONING TOOL Kjcll A. Falck-Pedersen, Park Forest, 111., assignor to Acme Steel Company, Chicago, 111., a corporation of Illinois Filed Sept. 24, 1956, Ser. No. 611,524

9 Claims. (Cl. 254-79) This invention relates to improvements in strap tensioning tools and its purpose is to provide an improved device or drawing a metal strap taut around a box or package preliminary to uniting the overlapping ends of the strap by forming an interlocking joint in any well known manner as, for example, by deforming a metal seal and portions of the strap ends surrounded by the seal. In the binding of packages, it has heretofore been the usual practice to use hand tools which enabled the operator to draw the strap taut with a relatively low tension, perhaps from 400 to 500 pounds per square inch, which has been satisfactory for most purposes. However, it has become desirable to set up higher degrees of tension in the binding straps in some operations and tensioning tools of the manually operated type and also of the power operated type have been provided for accomplishing that result.

When using strap stretching devices for developing a high tension in the strap wherein a rotary gripping wheel engages the strap to draw it taut, it has been found that the rotation of this wheel causes the strap to curl longitudinally in a direction tending to conform to the curvature of the wheel. This curvature of the strap tends to increase as the tension in the strap increases. This condition has the disadvantage that when the supply portion of the strap is cut off after a joint has been formed, the supply end of the strap is left with a longitudinal curl which makes it difficult to thread this end of the strap into a tool for another strapping operation.

The present invention involves the discovery that the above mentioned difiiculty may be overcome by providing opposite to the strap tensioning wheel a strap seat having a'curvature which is opposite to that of the tensioning wheel whereby the curling of the strap is prevented and the supply portion thereof is longitudinally straight when it is cut ofi.

This improvement may be applied to strap tensioning tools of two different types. In the first type of tool the ends of the strap overlap after being passed around the package and the rotary tensioning wheel causes one end portion of the strap to slide over the other end during the tensioning operation. In the second type of tool,

known as the pusher type, the free end of the strap is passed through the tubular seal which is to form a part of the joint and is reversely bent while the supply portion of the strap also passes through the seal after being looped around the package. In this second type of tool the free end of the strap is held by a part of the tool abutting against the end of the seal and the supply portion of the strap is then moved endwise by the rotary tensioning wheel in order to draw the strap taut. In the first type of tool where the two strap portions overlap, it is necessary to provide a strap seat having a high coeflicient of friction for engagement with the lower strap in order that this portion of the strap will be held against movement while the upper portion slides over it during the tensioning process. In the second type of tool, however, it is desirable to provide a strap seat having a smooth surface 2,986,376 Patented May 30, 1961 and a low coefficient of friction so that the strap may slide freely over the strap seat upon rotation of the tensioning wheel. In either form of tool, the present invention contemplates the use of a strap seat which is longitudinally curved in a direction opposite to the curvature of the periphery of the tensioning wheel. With either type of tool, it has been found that the use of a strap seat having a longitudinal curvature opposite to that of the tensioning wheel greatly reduces or substantially eliminates the longitudinal curvature which has heretofore been found to be present in the supply end portion of the strap.

In practice, it is usually desirable to provide a strap seat having a curvature which is greater than that of the tensioning wheel to facilitate the manufacture thereof and to reduce the necessary thickness of the strap seat. It has been found that a satisfactory tool embodying the improvement of the present invention may be formed with a rough or serrated strap seat having a curvature which is twice that of the periphery of the tensioning wheel. Such a tool has worked satisfactorily with metal strapping having a thickness of .035, where the improvement was embodied in a tool of the first type in which a double thickness of the strap is positoned on the strap seat. With a tool of the pusher type a strap seat having a smooth surface of a 6 inch radius has been found to serve satisfactorily with a tensioning wheel having a radius of /a inch. These dimensions are given merely by way of example and other degrees of curvature may be successfully employed.

When the strap seat has a smooth strap engaging sur face it may have a greater radius of curvature than the curvature of a strap seat which is toothed or serrated for the reason that the serrated teeth penetrate the contacting strap and tend to increase any tendency of the strap to conform to the curvature of the tensioning wheel, whereas, when the strap seat is smooth there appears to be a greater resistance to the tendency of the strap to coform to the curvature of the wheel. There is a greater tendency for the longitudinal curling of the strap when the strap is relatively thin and it is, therefore, desirable to provide a strap seat having a greater degree of curva ture when the thin-strapping is employed. Other features and advantages of the invention will appear more fully hereinafter.

The nature of the invention will be understood from the following specification taken with the accompanying drawings in which two embodiments are illustrated.

In the drawings,

Figure 1 shows a top plan view of a strap tensioning tool of the type wherein two thicknesses of the strap extend beneath the tensioning wheel and one portion of the strap slides over the other during the tensioning operation;

Fig. 2 shows a side elevation of the tensioning tool illustrated in Fig. 1;

Fig. 3 shows an end elevation of the tensioning tool illustrated in Figs. 1 and 2;

Fig. 4 shows a sectional view taken on the line 4-4 of Fig. 2;

Fig. 5 is a somewhat diagrammatic illustration of the use of the tools shown in Figs. 1 and 2 during the binding of a box or package;

Fig. 6 shows a sectional view taken on the line 66 of Fig. 3, illustrating a top plan view of the strap seat;

Fig. 7 shows an enlarged top plan view of the strap seat illustrated in Figs. 3 and 6;

Fig. 8 shows an end elevation of the strap seat illustrated in Fig. 7, illustrating the curvature of the top surface of the seat;

Fig. 9 shows a partial side elevation and a partial 1ongitudinal vertical section through the tool illustrated in Fig. 2 when the operating lever has been moved to a position wherein the pawl is automatically released from the ratchet wheel;

Fig. 10 shows an enlargediside elevation of the lower portion of" the tool illustrated in Fig. 1, showing the engagement of the overlapping strap portions by the rotary tensioning wheel and the strap seat;

Fig. 11 is a partial side elevation and partial longitudinal vertical section, similar to that of Fig. 9, illustrating by dotted lines the position of the operating lever when it is in its lower operatin'g position. and illustrating by full lines the position of the lever when it is in an extreme position for the purpose of: elevating the gripping dog from its normal gripping position;

Fig. 12 shows an enlarged side elevation of the strap stretching head portion of a tensioning tool of the pusher type wherein a single thickness of strap extends between the tensioning wheel and the strap; seat;

I Fig, 13 shows a sectional view taken on the line-13- 13 of Fig. 12; and

Fig, 14 shows a vertical section taken on the line 1414 of Fig. 12.

As illustrated in Figs. 1 to 11, inclusive, of the drawings the invention is embodied in a strap stretching tool comprising a frame 15 having a base portion 15a adapted to rest upon a box or package or other object to be bound. This frame is provided with an integrally formed handle 15]) which is adapted to be engaged by one hand of the operator for thepurpose of holding the tool in its proper position on a box or package such as the box 16 shown in Fig. 5. The base 15a isprovided with two lateral projections or flanges 15c and 150' which are adapted to underlie the metal binding strap 17 whilethis strap is being drawn taut around the box or package. The strap 17 may be withdrawn from a coil 18 and it, is first extended around the box 16 with the free end 17a thereof. extending over the flange 15c and somewhat beyond that flange toward the right hand end of the tool as seen in. Fig. 5.. The supply portion 17c of the strap, after being extended around the box 1-1,,is carried over the'flange 15d and above the strap extremity 17a over the flange 150. The loop 1712 around the box 16 may then be contracted manually to a considerable extent preliminary to the operation of the tool fordrawing the strap taut around'the box.

The mechanism by which the strap'is drawn taut is actuated by a lever 20 which is provided atone end with a ball 20a adapted to be engaged by one hand of the operator and to be reciprocated in a vertical plane to actuate the strap tightening mechanism. This mechanism comprises a yoke 21 which is pivotally mounted uoonapin 22 extending through apertures in two lugs 15c and 15f formed integrally with the base plate 15:14 The pin 22 is secured in position by a small vertical pin 23 which is mounted in anapertureformed in the lu 152 so that it extends through a transverse hole formed in the pin 22. The yoke 21 has two parallel arms 21:! and 21b which extend transversely to the pivot pin 22, as shown particularly in Fig. 4; The arm 2111 has journaled therein the reduced portion 24a of a shaft 24 which extends loosely through an aperture 210 formed in the arm 21b. The operating lever 20 is provided at itslower endwith two spaced side plates 2% and 29c which extend between the arms 21a and 21b of the yoke and which are apertured for engagement by portions of the shaft 24. The side plate 21b is rotatably mounted upon the reduced portion 24a and the side plate 20c is rotatably mounted upon an enlarged portion 24b of the shaft. Between the parts 24a and 24 12, the shaft 24 is provided with a fluted portion 240 which has a spl ined engagement with a ratchet wheel 25 adapted to be operated by the reciprocation of the lever 20 for the purpose of efiecting the rotation of the shaft. The reduced'portion 24a'of the shaft terminates in a threaded 4 part 24d which is engaged by a washer 26' and a nut 27 for holding the shaft in position in its bearing.

The enlarged portion 24a of the shaft which extends loosely through the aperture 216 of the arm 21b is connected to a fluted portion 24 which has a splined engagement with the disk 30a of arcup-sliaped gripping wheel 30. The arm 21b of the yoke 21 is provided with a cylindrical portion 21d upon which a cylindrical bearing member 31' is secured with a press fita'nd the;cylindrical gripping; portion 30b of the grippingmember isrjournaled upon the bearing member 31. The shaft 24 terminates beyond the gripping member 30 in a threaded portion 24g upon which a washer 32 and'a nut'33 are secured to hold the gripping member in driving engagement with theshaft. The cylindrical portion 30b of the gripping wheel is provided with an annular series of diagonal teeth 300 which are adapted to engage the upper side of the strap '17 above the flange 15c of the frame.

This flange is provided with a recess 15g, shown particularly in Fig. 10, in which there is mounted a hard metal gripping plate 34 which forms the strap seat for the end portion of the strap 17 which has been passed around the box or package 16. This gripping plate is held in place in the recess 15g by a set screw 35 extending upwardly through the flange 15c and it is provided on its.

upper side with a transverse curvature surface 340! which is convex upwardly, as shown particularly in Fig. 8, so that its curvature is opposite to that of'the curvature of the serrated surface 30c of the gripping wheel 30. The surface 34a is serrated along lines parallel to the axis of rotation of the gripping wheel as shown in 3% and it is also provided with a series of parallel grooves 34c which extend parallel to the longitudinal axis of the strap seated thereon, thereby providing a plurality of series of teeth 34d which rows extend parallel to each other and parallel to the longitudinal axis of the strap. The teeth which are thus formed are inclined toward the right as viewed in Figs. 2, 5 and 10, so that they tend to dig into the underlying end portion 17a of the strap and to resist the movement of this end portion of the strap toward the left, as viewed in Fig. 5, during the tightening of the strap around the box. This tightening operation is effected by the rotation of the gripping wheel 30 in contact with the supply portion of the strap which is then moved endwise over the portion 17a toward theleft as viewed in Fig. 5.

Therotation of the gripping wheel 30 is effected through the shaft 24 by the ratchet wheel 25 which, in turn, is actuatedby the reciprocating lever 20 through a pawl 38 having anarm 38a adapted to be engaged by thefingersof the operator, and havinga tooth 38b adapted to engage the teeth 25:: of the ratchet wheel 25. The pawl 38 is-pivotally mounted upon a pin 39 which extends between theside plates 20!; andt20c of the lever 20. A coil-spring. 40 is mounted on the pin 39 withina slot 380 whichextends transversely. through the pawl 38. This spring. has one arm 40a which engages a shoulder 20d on the lever 20 and it has another arm. 40b which engages one wall of the slot 380 so that the spring acts normally to move the pawl 38 into a position where the tooth 38b engages a tooth 25a of the ratchet wheel as shown in-Figs. 2 and 12, In the normal operation of theme], the lever- 20 is reciprocated toward and-from thehandle-lSb with the result that the tooth 38b of the pawl engages the ratchet wheel teeth" to efiect the rotation of the ratchet wheel'upon movementof the lever lti toward'the handle 1% but; upon the reverse movement of the lever 20, the tooth 38b slides=over the teeth of the ratchet wheel as permitted by the compressionof the spring 40.

Between successive tensioningstrokes of the hand/lever 20, the ratchet wheel 25 and; the tensioning wheel 30 are both held in the positions to; whichtheyhavebeen adcanced by means of a detent 42, best shown'in Figs, 9-andl1, which is pivoted on apin 43 extending between the upstanding lugs 15:: and'15f in which the pin 22is mounted,v

The detent 42 has a tooth 42:: which is adapted to engage the teeth 25a of the ratchet wheel to hold the ratchet wheel and the tensioning wheel against reverse rotation, as shown in Fig. 9. During the forward stroke of the hand lever 20 toward the right, as viewed in Fig. 2, the detent 42 slides over the teeth of the ratchet wheel with which it is normally maintained in contact by means of a coil spring 44 mounted on the pin 43 in a slot 42b which is formed in the detent. One arm 44a of the spring 44 engages the wall of this slot and the other arm engages an aperture h formed in the base plate 15a so that, during a reverse stroke of the lever 20, the detent tooth 42a engages a tooth of the ratchet wheel 25 to hold the ratchet wheel and the tensioning wheel 30 in the positions to which they have been moved during the time that the hand lever is being returned for another working stroke.

The feed wheel 30 is normally maintained in contact with the strap 17 being operated upon by means of a coil spring 45 which extends between the lug 15) of the base 15:: and an arm 21e which is formed on the yoke 21 to extend radially from the axis of the shaft 24, as shown in Fig. 2. The lug 15f and the arm 212 are provided with projections 46 which hold the spring 45 in position. This spring acts normally to pivot the yoke 21 about the pin 22 toward the right, as viewed in Figs. 2 and 11, so that the yoke is normally moved to the position where'the peripheral surface 30b of the tensioning wheel will engage the upper surface of the supply portion 170 of the strap, as shown particularly in Fig. 10. This normal feeding position of the tensioning wheel 30 is adapted to be regulated by an adjusting screw 48 to perform properly upon metal straps of various thicknesses.

For the purpose of elevating the tensioning wheel 30 away from the strap and from the strap seat 34, which is desirable when the tensioning tool is adapted to be removed from a box or package which has just been strapped, means are provided for swinging the yoke 21 upwardly about the pivot pin 22 until it occupies the elevated position shown in Fig. 11. For this purpose, the pawl 38 is provided adjacent to the tooth 38b with a cam surface 38d. The normal retracted position of the hand lever 20 is shown by dotted lines in Fig. 11 but, when the lever is swung beyond this position to that shown by full lines in Fig. ll, the cam surface 38d engages a flat cam face 15g which is formed on the handle 15b, so that the tooth 38b of the pawl then coacts with a tooth of the ratchet wheel 25 to raise the yoke 21 upwardly to the position shown in Fig. 11 with the heel of the cam 38d resting on the flat cam surface 15g.

When the lever 20 reaches the extreme position shown by full lines in Fig. 11, the detent 42 is moved out of engagement with the ratchet wheel by the action of two arms 42b which are formed on the sides of the detent 42 and which are angularly disposed with respect to the arm of the detent, so that their extremities engage shoulders 20e which are formed on the side plates 20b and 200 of the hand lever 20 at the ends of the arcuate surface 207. In the normal operation of the lever 20, the arms 42b ride over the arcuate surface 20 without effecting the operation of the tooth 42a of the detent in engaging the teeth 25a of the ratchet wheel but, when the lever 20 has been moved to the extreme position shown by full lines in Fig. 11, so that the yoke 21 is elevated, the shoulders 20e operate to elevate the arms 42b and thereby raise the detent 42 away from the ratchet teeth.

In order to move the tooth 38b of the pawl out of engagement with the ratchet teeth, merely by the movement of the hand lever 20, without manually operating the pawl 38, means are provided for automatically disengaging the pawl from the ratchet wheel when the lever 20 is swinging in a counterclockwise direction toward the extreme position shown in Fig. 9. For this purpose, the hand lever 20 is provided adjacent to the slot 20 with a socket 20g in which there is mounted a spherical ball 49 actuated by a coil spring 50. In the normal reciprocating movements of the lever 20, the ball 49 rides upon a cam aesaara surface 3'8e which is formed on the pawl 38 and the tooth 38b moves into and out of engagement with the ratchet teeth as the tensioning of the strap proceeds. However, when the lever 20 is moved to the extreme position shown in Fig. 9, a surface 38 on the pawl engages the upper surface of the detent 42 and the pawl is turned about its pivot 39 until the ball 49 passes out of engagement with the cam surface 38:: and into engagement with a recess 38 which is formed in the pawl between the cam surfaces 38d and 382. The ball 49 then interlocks with the shoulder at the end of the recess 38g so that the pawl is held with its tooth 38b out of engagement with the teeth of the ratchet wheel. This is accomplished while the operator maintains his grasp on the lever 20 and this lever may then be returned toward the position shown by dotted lines in Fig. 11 or by full lines in Fig. 2, with the tooth 38b of the pawl out of engagement with the ratchet wheel. As the lever 20 approaches the end of this clockwise movement the cam surface 38e engages the flat face 15g of the handle 15b with the result that thepawl is turned so that the ball 49 again engages the cam surface 38e, whereupon the pawl is again moved by its spring 40 into engagement with the ratchet teeth with the lever 20 in a new position. Thus, the operator is enabled to vary the position of engagement of the tooth of the pawl with the ratchet wheel by a one-hand operation of the lever 20 without any manual manipulation of the pawl 38.

In Figs. 12, 13 and 14 of the drawings there is shown a second form of the invention in which the gripping plate or strap seat is embodied in a strap tensioning tool of the pusher type wherein a single thickness of strap lies between the strap seat and the tensioning wheel during the tensioning operation. In the embodiment illustrated in the drawings, the tensioning wheel is intended to be power operated but the improvement of the present invention maybe employed in a tensioning tool of the pusher type which is manually actuated. As shown in Figs. 12, 13 and 14, the invention is embodied in a tool having a stretching head illustrated generally at and comprising a frame 56 having a forwardly projecting flange 56a on which there is mounted a strap seat or gripping plate 57 which is secured in a recess in the flange 560 by means of a setscrew 58. A metal strap 59 extended around a box or package 60 to be bound has its free end 59a extended through a tubular metal seal 61 and reversely bent as shown at 5%. The strap 59 extends freely around the box or package 60 and the supply portion 59c thereof extends from the seal 61 over the flange 56a and thence over the gripping plate or strap seat 57, as shown particularly in Fig. 12.

The flange 56a has a tapered extremity 56b which is of substantial width and which is adapted to engage the lateral walls of the tubular seal 61 between the free end portion 59a of the strap and the supply portion 59c thereof. Also, a detent 63 is pivoted at 64 on the frame. 56 and its extremity 63a thereof is adapted to engage the top wall of the seal above the supply portion 590 of the strap in the same vertical plane as the extremity of the flange 56a of the frame. Thus, when a pull is exerted on the strap 59 by tension exerted on the supply portion 59c thereof, the strap is drawn taut around the box or pack age '60 and the free end 59a of the strap is held in position by the engagement of the seal 61 with the flange 56a and the detent 63.

The strap 59 is drawn taut around the box or package 60 in the manner just referred to by means of a rotary tensioning wheel 65 which is fixed on a shaft 66 and which is provided with a serrated gripping surface 65a adapted to engage the upper side of the supply portion 590 of the strap at a point opposite to the gripping plate or strap seat 57. This strap seat has a smooth upper surface 57a which is curved longitudinally of the supply portion 590 of the strap in a direction opposite to the curvature of the peripheral surface of the tensioning wheel 65 I so, that there is: obtained; theadvantag'e described. above,

whereby the strap is: drawn taut and; is, moved over the smooth surface of. the gripping plate 57" without-:- settingpermit the disengagement of the tensioning wheel with the supply portion 59c of the strap. The shaft has: formed integrally therewith agear, 71 arranged to mesh.

with adriving pinion 72mounted-upon a'shaft 73 adapted to be driven by a suitable power operated mechanism, not shown, which is not apart of the present invention.

In the embodiments of the invention'which have been described above, means have been shown for effecting the tensioning of a metal strap by means of a te-nsioningtool in which the strap is gripped between a rotary tensioning wheel and a. stationary gripping plate or strap seat which has its strap engaging surface curved in a plane containing the longitudinal axis of the strap and extending at right angles to the axis of rotation'of the tensioning Wheel, so that the strap may be drawn taut by the rotation of the tensioning wheel without causing any substantial longitudinal curvature to be imparted to the strap as it passes. between the tensioning wheel and the gripping plate. The gripping plate should have no transverse curvature on the strap-engaging surface thereof since that would-tend to bring about alongitudinal stretching of the center portionof the strap with a resultant longitudinal curving and channel. shaping of the strap which would interfere with the proper manipulation thereof in subsequent operations inthe formation of astrap joint. In eachform of apparatus described above the curvedsurface of the gripping plate or strap seat may be a segment of a cylindrical surface with its axis in the same plane as theaxis of the tensioning wheel. Sub stantially the same relative-arrangement of the opposed curved surfaces is preferable where the surface of the gripping plate is not a segment of a cylinder.

Although two embodiments. of the-invention have been shown and described by way of illustration, it will be understood that it may be constructed in various other embodiments without departing from the scope of the appended claims.

I claim:

1. The combination in a strap tensioning tool for drawing a strap taut about an object to be bound, of a frame adapted to reston said object, a strap seat carried by said frame for supporting. said strap and having a strap engaging surface which is. substantially straight laterally of the strap and is. curved longitudinally ofthe strap, and means including a rotary-tensioning wheel for engaging said strap opposite said seat and effecting the longitudinal movement thereof.

2. The combination in a strap tensioning tool for drawing a strap taut about an object to be bound, of a frame adapted to rest on said object, a strap seat carried by said frame for supporting said strap and having a strap engaging surface which is substantially straight laterally of the strap and is curved. longitudinally of the strap, and means including a rotary tensioning wheel for engaging said strap opposite said seat and effecting the longitudinal movement thereof; the curvature of the periphery of said wheel being opposite to the curvature of said strap seat.

3. The combination in a strap tensioningtool for drawing a-strap' taut about an object to be bound, of a frame adapted torest'on said object, a-strapseat carried by said frame for supporting: said strapa-nd having. a. strap engaging surface; which issubstantially straight laterally of the strap and is curved longitudinally of the strap,, and meansiincludingza rotary tensioningzwheel for engaging; said'strapopposite saidseat andeffecting the longitudinal movement thereof, the curvature of the periphery ofsaidwheel being opposite to the curvature of said; strap seat, 4 said longitudinally curved surface of said strap'seat being serrated transversely.

4. The combination in a strap tensioning tool for drawing a strap taut, about an object to be bound, of a frame adapted to rest on said object, a strap seat carried by saidv frame for supporting said strap and having a strap engaging surface which is substantially straight laterally of the strap and is curved longitudinally of the strap,- and means including a rotary tensioning wheel for engaging said'strap opposite said seat and effecting the longitudinal movement thereof, the curvature of the periphery of said wheel being opposite to the curvature of said strap seat, said longitudinally curved surface of said strap seat being transversely serrated and being provided with spaced longitudinal grooves.

5. The combination in a strap tensioning tool for drawing a strap taut about an object to be bound, of a frame adapted to rest on said object, a strap seat carried by said frame for supporting said strap and having a strap engaging surface which is substantially straight laterally of the strap and is curved longitudinally of the strap, and means including a rotary tensioning wheel for engaging said strap opposite said seat and effecting the longitudinal movement thereof, the curvature of the periphery of said wheel being opposite to the curvature of said strap seat, the centers of curvature of said strap seat and of said tensioning wheel being in the same plane.

6. The combination in a strap tensioning tool for drawing a strap taut about an object to be bound, of a frame adapted to rest on said object, a strap seat carried by said frame for supporting said strap and having a strap engaging surface which is substantially straight laterally of the strap and is curved longitudinally of the strap, and means including a rotary tensioning Wheel for engaging said strap opposite said seat and effecting the longitudinal movement thereof, the curvature of said strap seat being opposite to and greater in radius than the curvature of the peripheral surface of said wheel.

7. The combination in a strap tensioning tool for drawing a strap taut about an object to be bound, of a frame adapted to rest on said object, a strap seat carried by said frame for supporting the supply portion of. a strap looped around said object, means carried by said frame for abutting against a tubular strap seal to which the free end of said strap is attached and through which said supply portionis threaded, and meansincluding a rotary tensioning Wheel engaging, said supply portion for moving said supply portion over said strap seat and thereby drawing said strap taut about said object, said seat having a smooth strap engaging surface which is substantially straight laterally of the strap and is curved longitudinally of and away from said strap from the place of contact with said strap.

8. The combination in a strap tensioning tool-for draw ing a strap taut about an.object to be bound, of a frame adapted to rest on said object, a strap seat carried by said frame for supporting the supply portion of a strap looped around said object, means carried by said frame for abutting against a tubular strap seal to which the free end ofsaid strap is attached and through which said supply portion is threaded, and means including a rotary tensioning wheel engaging said supply portion for moving said supply portion over said strap seat andthereby drawing said strap taut about said object, said seat having a smooth strap engaging surface which is substantially straight laterally of the strap and is curved longitudinally of and away from said strap from the place of contact with said strap, the centers of'curvature of said smooth strap'engaging surface-and of the periphery'ofsaid wheel-being in the-same -planet 9. The combination in a strap tensioning tool for drawing a strap taut about an object to be bound, of a frame adapted to rest on said object, a strap seat carried by said frame for supporting the supply portion of a strap looped around said object, means carried by said frame for abutting against a tubular strap seal to which the free end of said strap is attached and through which said supply portion is threaded, and means including a rotary tensioning wheel engaging said supply portion for moving said supply portion over said strap seat and thereby drawing said strap taut about said object, said seat having a smooth strap engaging surface which is substantially straight laterally of the strap and is curved longitudinally of and away from said strap from the place of contact with said strap, the radius of curvature of said smooth surface being greater than the radius of curvature of the periphery of said wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,988,534 Abbott Jan. 22, 1935 2,569,623 Wognum Oct. 2, 1951 2,621,893 Childress Dec. 16, 1952 2,622,844 Abbott Dec. 23, 1952 2,638,314 MoFerren et a1 May 12, 1953

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