US3052178A - Strap guide - Google Patents

Description

M. B. HALL STRAP GUIDE Sept. 4, 1962 4 SheetsSheet 1 Filed NOV. 29, 1960 p 1962 M. B. HALL 3,052,178

STRAP GUIDE Filed NOV. 29, 1960 4 Sheets-Sheet 2 INVENTOR.

WMiQdJMJA W@Q%wu Sept. 4, 1962 M. B. HALL 3,052,178

STRAP GUIDE 4 Sheets-Sheet 3 Filed Nov. 29, 1960 INVENTOR.

M. B. HALL STRAP GUIDE Sept. 4, 1962 4 Sheets-Sheet 4 Filed Nov. 29, 1960 3,052,178 STRAP GUIDE Marchand B. Hail, Olympia Fields, Ill, assignor to Acme Steel Company, Qhicago, Ill, a corporation of Illinois Filed Nov. 29, 1960, Ser. No. 72,499 12 Claims. (Cl. 100-25) (This invention relates to the art of strap guide tracks and particularly to one which enhances the use of a conventional type track wherein a length of strapping is guided around an object to be strapped prior to tensioning of the strap on the object and connecting together the ends of the strap length.

When strapping objects at the present time, it is common to secure the object or load by means of the straps to an underlying support pallet which provides a convenient means on which the object can be supported during subsequent handling, storage and shipment. On certain type pallets where the pallet consists of a platform supported by post type legs or longitudinal runners, little difficulty is encountered in properly encircling the straps around the pallet to secure it to the load or object which it supports. However, when a double faced pallet is used, viz., one which consists of two parallel faces or sheets spaced apart by means of spacers or legs, it is desirable that the straps extend in the space between the two faces of the pallet so that the upper face only is actually strapped to the object. The obvious way of threading the straps through this space is manually by passing the leading strap end from one side of the pallet to the other. This is a time consuming operation and does not lend itself to high enough production to keep abreast of the swiftness of the ordinary high speed assembly line.

It is, therefore, the principal object of this invention to provide an improved strap guide track having novel retractable means which can be extended into the space between the two faces of a double faced pallet where the means provides a guide for facilitating the passage of a strap length endwise through the space so that a strap can be quickly and easily encircled around an object supported on the pallet.

In order to accomplish this object, it is another object to provide a novel type retractable guide which can be first inserted into the space of the pallet when the strap is to be encircled on the object, and then retracted after encircling of the strap has been completed.

The form of the retractable means of this invention is a metal slat which is bowed into a transverse concavoconvex cross section to first provide rigidity for proper support of a strap and secondly provide a trough into which the strap can be properly guided. Also, for space conservation, the metal slat is retracted by rolling it up into a coil which can be unwound when the metal slat or guide is extended.

It is another object of the invention to provide a retractable guide as described which is powered by a suitable motor having an improved control means for arresting the movement of the guide at the ends of both its extended and retracted positions. The improved control means is advantageous for accurately predetermining both the extended and retracted positions.

In a copending application entitled Strap Guide of Alvin L. Winkler, Serial Number 27,556, filed May 29, 1960, now Patent No. 2,985,098, patented on May 23, 1961 there is described and shown a retractable metal slat strap guide of the same type as shown and described in this application. However, in that application the strap guide is bent around a pulley and raised vertically when retracted with the disadvantage that much space is used for the vertical support required. The invention of Bfiiifili Patented Sept. 4, 1962 ice this application is an improvement over the invention of that application, primarily because of its compactness which facilitates its use in the many places where space is a problem.

Other objects and advantages of the invention should become apparent upon reference to the accompanying drawings, in which FIG. 1 shows a partially cutaway and partial sectional side elevation of strapping apparatus embodying the invention;

FIG. 2 is a sectional view along the line 22 of FIG. 1 showing the relationship of the strap guide path between the faces of a pallet;

FIG. 3 shows a partial sectional and simplified side elevation view of the belt driving means for the retractable guide;

FIG. 4 shows an enlarged view of the lower right hand portion of FIG. 1;

FIG. 5 shows a top plan view of the strap guide unit of FIG. 4;

FIG. 6 shows a sectional view along the line 66 of FIG. 4;

FIG. 7 shows a sectional view along the line 77 of FIG. 4;

FIG, 8 shows a sectional FIG. 4;

FIG. 9 shows an enlarged top plan view of the power control means;

FIG. 10 shows an enlarged front view of the same power control means of FIG. 9;

FIG. 11 shows an enlarged end view of the power control means of FIG. 9;

FIG. 12 shows a still further enlarged sectional view of certain portions of the power control means for illustrative purposes;

FIG. 13 shows a sectional view along the line 13-13 of FIG. 1 and particularly shows the cross sectional shape of the form of strap guide to be used with the invention; and

FIG. 14 shows a simplified schematic wiring diagram of the electrical control circuit for controlling the power operation of the invention.

The particular embodiment of the invention as shown is mounted on a frame 1 which ordinarily rests on the floor where the invention is to be used. The frame 1 is provided with a conveyor 2 consisting of a plurality of spaced parallel positioned rollers 3 journaled to the frame I. These rollers 3 are freely journaled so that an object can be rolled across their upper surfaces with a minimum of effort. Secured to the rear of the rollers in a vertical direction from the frame 1 is an upright member 4 whose upper end is provided with a horizontal arm 5 extending in cantilever from it and directly over the region of the conveyor rollers 3. Secured by means of L-shaped clips 6 on either side of the upright member 4 and the horizontal member 5 is a flexible strap guide tube 7. The clips are held in place on the members 4- and 5 by means of screws 8 as best shown in FIG. 13. The guide tube '7 terminates at its upper end 9 slightly beyond the end of the horizontal member 5 while its lower end 10 terminates approximately slightly above the level of the rollers 3 and in the vicinity of their rear ends.

The guide tube "7 is preferably manufactured from flexible plastic or rubber and can be extruded into the cross sectional shape shown in FIG. 13. Although this plastic tube type guide is shown, there are many other ways of manufacturing guide tubes to perform the same general function and the particular structure shown forms no part of the invention per se, as hereinafter claimed.

Since plastic or rubber ordinarily is soft enough that it can create a snag problem with the leading end of a view along the line 8 -8 of 2) strap fed through a guide tube made from it, a backing strip 11 of stainless steel or other smooth metal is positioned through the tube for its entire length. Its ends 11a and 1112 are cur-led around the ends 9 and 10 of the tube in order to retain it positioned in the tube.

Extending parallel to the horizontal arm is another arm 12 Which is also supported in cantilever from the upright member 4-. it is supplied with a motor 13 having a feed wheel 14 mounted on its shaft. Directly below the feed wheel 14 is an idler wheel 15 mounted on another shaft. The idler wheel 15 is positioned. closely enough to the feed wheel 14 so that when strap 16 is positioned be-. tween the two Wheels 14 and 15 and the feed wheel 14 is rotated, the strap 16 is caused to move longitudinally between the wheels in a direction dependent upon the direction of rotation of the feed wheel 14. The idler wheel 15 is necessarily free wheeling in either direction. For convenience, the idler wheel 15 can be made retractable away from the feed wheel 14 to permit easy removal of the strap 16 when necessary but this forms no part of the invention.

The guide tube 7 is provided with an enlarged base 7a which is the portion held by the clips 6'. Attached to the base portion 7a are two flexible arms 7b and 70 which in their normal positions abut at their ends along a line of contact 7d. In these positions, the arms 7b and 70 form a circle having a longitudinal circular opening 7e extending entirely through the guide tube 7 from one end to the other. When the guide tube is used for guiding strap around an object, the strap 16 is passed entirely through the guide tube '7. When it is necessary to remove the strap from the guide tube 7 the strap is pulled way from the guide tube and the pulling force causes the strap 16 to cam against the arms 7 b and 7c and spread them apart to the positions as indicated in phantom lines in FIG. 6 where an opening large enough for the strap 16 to be removed is created. After the strap is removed, the natural resiliency of the arm 7b and 7c causes them to return to their initial positions. Since the arms 7b and 7c are flexible for their entire length, the strap 16 can be stripped from the tube 7 progressively from end to end.

At the rear of the frame 1 is mounted another frame 17 which consists of two vertically spaced base plates 17a and 17a which are secured to the lower edges of two large side plates 18 and 19 which extend upwardly above the base plates 17a and 17a. These two side plates 18 and 19 support all of the mechanism related to the retractable strap guide and can be referred to as the retractable strap guide unit.

Journaled on spaced bearings 21? and 21 in the side plates 18 and 19 is a drum shaft 22 on which is secured, by means of a set screw 23, a drum 24. Around this drum is ordinarily wrapped the retractable strap guide 25. This strap guide 25 is, in its extended position, in the form of a large slathaving a concave-convex cross sectional shape. The slat or guide is preferably made of thin steel strip formed with the requisite transverse curvature, but can probably be manufactured s'atisfac torily from plastic or other flexible material. The inner end of the guide 25 is bifurcated to have two spaced ears 25a and 25b connected to two loops 26 which are fitted over opposite ends of a pin 27 secured through an aperture 28 in the drum 24. By proper guiding of the guide 25 as the drum 24 is rotated, the guide 25 is Wound, layer upon layer, onto the drum 24, and the pin 27 maintains the guide connected to the drum 24.

As viewed in FIGS. 1, 4 and 5, the guide 25 ordinarily projects beyond the drum 24 with its free end 29 adjacent to the end of the guide tube 7. When a pallet 46 supporting -a load 46a is properly positioned on the conveyor 2 at the strapping station adjacent to the guide tube 7, in order to guide the strap 16 in the space 48 between the two parallel faces 46b and 460 of the pallet 46, the guide 25 is unwrapped from the drum 24 by rotating the drum in -a clockwise direction so that the end 29 of the guide is projected into the space 48 which is in the end of the shaft which is there threaded.

path of the strap 16 leading from the lower end 10 of the guide tube 7. With the strap guide positioned in this manner, the strap 16 as it isfed forward in the direction of the arrow 49, is guided through the opening 48 of the pallet so that its leading end 16a emerges beyond the opposite side of the pallet. After this threading operation through the pallet is completed, the two ends of the strap 16a and 1617 are tensioned to withdraw the strap 16 out of the guide tube 7 and tightly around the sides of the package 46a supported on the pallet. Conventional strapping tools can then be used to tension the strap tightly, secure the ends 16:1 and 16b together and sever the secured strap loop on the package from the supply end 16b which can still be connected to a source of strap supply.

In order to properly guide the strap guide 25 as it is either extended or retracted, its marginal edges are guided in four grooved edge rolls 3d, 31, 32 and 33 which are each journaled on a bracket 34 secured to the side plates 18 and 19. These guide rolls 30 to 33 guide the strap guide 25 in a horizontal direction, but could just as well be conditioned to guide the strap guide in an angular direction if such a condition would be required, as in a situation where the conveyor may be sloped.

There are two other guide rolls 35 and 36 which are each journaled in a bracket 37 and these guide rolls 35 and 36 are positioned to contact the edges of the strap guide 25 in a portion of the periphery of the drum where the layers of the strap guide 25 build up as it is wrapped onto the drum 24. The purpose of these guides is to keep the wrapped convolutions of the strap guide in alignment with each other. In addition to the guide means just mentioned for the strap guide, it is necessary to provide a driving means to cause the strap guide 25 to be either extended or retracted. The means for accom-. plishing this is a flexible belt 38 wrapped around the coiled strap guide 25, as especially viewed in FIG. 3. The belt 33 is wrapped around about three-fourths of the circumference of the wrapped strap guide and is directed around four belt pulleys 39, 4t), 41 and 42, to maintain the belt in a closed loop path. All four of these pulleys are suitably journaled on four shafts 43, 4d, 45 and 46 mounted between the side plates 18 and 19. Each of the shafts 43 to 46 are provided with spacer sleeves 47 on both sides of their respective pulleys so as to maintain the pulleys centrally located 'on the shafts.

Although the pulleys li, 41 and 4-2 are all idlers, the pulley 39 is driven. Its shaft 43 is journaled in bearings 47 and 4S. Adjacent each bearing is a spacer sleeve 49 which abuts both the inner race of a bearing 47 or 48 and the inner race of a more centrally positioned bearing 59 or 51, these bearings 59 and 51 being on immediately opposite sides of the pulley 39. At one end of the shaft 43 it is provided with a spring 52 mounted between the bearing 4% and a double nut 53 which is secured on the The spring 52 reacts between the inner race of the bearing 48 and the nut 53 to urge the shaft 43 in a direction toward the right, as viewed in FIG. 7. On the other end of the shaft 43 is secured a pulley 54 and between it and the inner race of bearing 47 are two spacer sleeves 55 and 56. The effect of urging the shaft 43 to the right is to draw all of the sleeves in the inner races of the bearings toward each other and thereby clamp the inner races of bearings 54) and 51 across the pulley 39. This clamping action creates a frictional drive condition between the shaft 43 and the pulley 39 so that, upon rotation of the pulley 54, the pulley 39 is rotated. The purpose of this frictional drive is to provide a safety overload feature which permits slippage of the pulley 39 or its driving shaft 43 in case of jamming.

From this driving arrangement shown it should be evident that rotation of the pulley 39 in a clockwise direction causes the strap guide 25 to be retracted and wound about the drum 24, while rotation of the pulley 3% in the opposite direction causes the strap guide 25 to be extended as the strap guide is unwound from the pulley 24.

The means for driving the pulley 54 which drives the pulley 39 is by means of another belt 57 which is driven from the pulley 58 of a motor 59. This motor 59 is mounted between the top edges of the side plates 18 and 19 and is preferably an electric motor, although other types can be used.

Although it is not essential, it is desirable to have a control system for the motor which permits predetermined actuation of it so that the retractable guide is either extended or retracted a deliberate amount each time it is actuated without requiring that the operator guess when to energize and tie-energize the motor.

The control system for the motor is particularly shown in FIGS. 6, 9, 10, 11 and 12. The end of shaft 22 which passes through bearing 20 is threaded and projects quite far beyond the side plate 18 in which the bearing 20 is mounted. This threaded end 22a of the shaft 22 is first provided with two threaded nuts 60 and 61 which can be locked together in a fixed position on the shaft 22 by means of two lock washers 62. The nut 61 is provided internally with the inner end of a helical spring 63 which is welded or soldered to it. The spring 63 acts as the threads of the nut 61 and engages the threads on the end 22a of the shaft 22. The nut 60 is internally threaded to directly engage the threads of the shaft end 2211. With the spring 63 securely bonded to the nut 61 as described, rotation of the nut 61 on the threads of the shaft end 22a causes rotation of the spring 63 with it. Beyond the free end 63a of the spring 63 is mounted an inverted U-shaped bracket 64 by means of an internally threaded circular nut 65. The circular nut 65 has an enlarged center portion having annular end walls 65a. guided against the inside walls of the bracket 64 and it also has reduced diameter ends 65b and 650 which project into round openings 66 and 67 in the side walls of the bracket 64. Through apertures in the side walls of the bracket 64 is also mounted a screw 68 which is held in place by means of a nut 69 at its end. The effect of tightening of the nut 69 on the screw 68 is to draw the two side walls of the bracket 64 together and thereby clamp the circular nut 65 fixed relative to the bracket 64. When rotation of the circular nut 65 is required for adjustment, the nut 65 is loosened so that the pressure of the side plates of the bracket 64 is relieved against the ends of the circular nut 65, at which time the circular nut is free to be rotated relative to the bracket 64. During this rotational movement, it is urged one way or another on the shaft 22 because of its threaded engagement with it. The purpose of this adjustment of the circular nut 65 is hereinafter described.

Adjacent to the extreme end of the shaft end 22a are two more nuts 70 and 71. The nut 71 is similar to 60 and is internally threaded to directly engage the threads of the shaft 22 and it is a locking nut for nut 70. The nut 70 is similar to nut 61 and is provided with a helical spring 72 which is soldered r welded to it in the same manner. The spring 72 acts as the internal thread for the nut 70 on the threads of the shaft 22. Rotation of the nut 70 causes rotation of the spring 72 and causes the spring to move one way or the other longitudinally on the shaft, depending upon which direction the nut 70 is rotated.

On the outer surfaces of the side walls of the bracket 64 are mounted two switches 73 and 74. These switches have actuating arms 73a and 7 4a which extend transversely over the shaft 22. These switches 73 and 74 are secured by means of screws 75 to the side walls of the bracket 64. The bracket 64 is provided with a pin 76 which has its inner end secured to the side plate 18 while its outer end is secured through the side walls of the bracket 64. This pin maintains the bracket 64 in a fixed angular relationship to the shaft 22.

With the switch actuating arm- s 73a and 74a positioned laterally across the shaft 22 in the path of the springs 63 and 72, as the bracket 64 is moved along the shaft 22 in one direction or another, the arms 73a and 74a. are actuated alternately by contact with the ends 63a and 72a of the two springs.

In actual operation, the switches are used to arrest the operation of the driving motor 59 upon both retraction and extension of the strap guide 25. In FIG. 9, it may be assumed that the positions of the switch arms 73a and 74a are as they would be when the strap guide is extended into the space 48 between the pallet faces 46b and 46c. In this case the arm 74a is pivoted upwardly onto the spring end 72a. In this position of the arm 74a, the contacts of switch 74 are open. At this same time, the arm 73a is off of the spring end 63a and resting upon the threads of the shaft 22. In this position of the arm 73a, the contacts of the switch 73 are closed. When it is desired to retract the strap guide 25, another switch in series with switch 73 is closed and this energizes the motor 59 to cause rotation of the coil of strap guide 25 in a direction to cause it to be further wrapped onto the drum 24. As the drum 24 is rotated in this manner, its shaft 22 is likewise rotated and this shafts threaded engagement with the circular nut 65 causes the bracket 64 to be moved toward the left as viewed in FIG. 9. Movement of the bracket 64 to the left causes the switches 73 and 74 to likewise be moved to the left relative to the shaft 22 so that the switch arm 74a falls off of the end 72a of the spring and onto the threaded portions of the shaft 22 to close the contacts of the switch 74. Shortly thereafter, when the bracket 64 has moved far enough, the switch arm 73a contacts the end 63a of the spring 63 to cause the arm 73a to be raised to open the contacts of the switch 73. Closing of the contacts of switch 7 4 prepares the circuit for again causing the strap guide to be extended, While opening of the contacts of switch 73 breaks the circuit with the electric motor 59 and thereby arrests the operation to arrest the retraction of the strap guide 25. In this manner, by having the springs 63 and 72 properly spaced, it is possible to accurately determine the limits of movement during extension and retraction of the strap guide 25.

The fit of the pin 76 through the walls of the bracket 64 is loose enough that the bracket 64 is free to move over it as the shaft 22 is rotated to cause such movement.

FIG. 12 indicates schematically the reason for the adjustment of the circular nut 65 relative to the bracket 64. If the initial angular position of where the start of the internal thread of the circular nut is not proper, it is possible that the switch arm 74a will possibly first contact the end 72a of the spring 72 at a position indicated by phantom lines in that view. In that position it is possible that insufiicient movement of the switch arm 74a will not have occurred to completely actuate the switch. If this is true, the nut 69 is loosened and the circular nut 65 is adjusted until arm 74a is upon the spring end 72a as shown in solid outline in FIG. 12.

By referring to FIG. 14, the entire electrical operation of the controls involving switches 73 and 74 can be described. In FIG. 14, a suitable supply voltage is applied between wires 77 and 78. Upon closing of a master switch 79 connected to these wires 77 and 78, the voltage is carried between conductors 80 and '81. At this time, none of the electrical components are energized. However, switch 73 is closed because its switch arm 73a is off of the end 63a of the spring 63 and switch 74 is open because its arm 74a is on the spring end 72a. Also, as previously described, the guide 25 is extended at this time. In order to cause reversal or retraction of the guide 25, the reverse switch 82 is closed manually. This applies voltage from conductors 80 and 81 across a relay solenoid 83 by way of closed switch 73. This energizes solenoid 83 to cause the solenoid contact switches 83a and 83b to be closed. Closing of contact switch 83b maintains solenoid 83 energized after the reverse switch 82 is spring returned after release by the operator. Contact switch 83a energizes the electric motor 59 through conductors 84 and 85 so that the motor 59 rotates in a direction corresponding to that required for retraction of the guide. As the guide 25 is retracted, the bracket 64 is moved to the left, as viewed in FIG. 9, because of rotation of the shaft 22 during this time. The movement of the bracket 64 correspondingly moves the switches 73 and 74 to the left with it. At a predetermined time, determined by the spacing between the spring ends 63a and 72a, the switch arm 73a rides up on to the spring end 63a to cause switch 73 to be opened. During the initial movement of the bracket 64, however, switch 74a is closed as the spring arm 74a falls off of the spring end 72a. Opening of switch 73 de-energizes relay solenoid 83 to allow the spring return of its contact switches 83a and 83b to open. Opening of switch contact 8311 sets up the circuit for the next cycle of operation while opening of switch contact 83a tie-energizes the motor 59 and arrests its motion. When the motion of the motor 59 has come to rest, the guide 25 will have also been arrested in its movement so that it is completely retracted.

When it is again desired to extend the guide, a forward switch 86 is closed manually to energize a relay solenoid 87 through the closed switch 74. Energization of the solenoid 87 causes its switch contacts 87a and 87b to be closed. 87b is a holding contact for solenoid 87 to maintain it energized after the actuating button for the forward switch 86 is spring returned upon manual release. Closing of switch contact 87a energizes the motor 59 through conductors 88 and 85. Since the motor 59 is a reversing type motor wherein its direction of rotation is determined by whether it is energized through conductors 84 or 88, energizing this motor 59' through the conducter 88 causes it to be rotated in a direction to cause the guide 25 to be extended. When the shaft 22 rotates sufliciently, the bracket 64 will have moved sufliciently to the right that the switch arm 73a will have moved ofl of the spring end 6311 to close switch 73 and the switch arm 74a will have moved onto the spring end 72a so that the switch 74 is again opened. The parts are then all in the positions as shown in FIGS. 9 and in readiness for the cycle to be repeated.

Although a control system has been provided for predetermining the extension and retraction of the strap guide automatically, it should be apparent that the operator could control the motor 59 by having the forward and reverse switches 86 and 82 in series with the conductors 88 and 84 respectively so that reversal of the motor and its stoppage and starting can be controlled directly by manual means. This is not too desirable, however, since much greater skill is required of the operator than is thought reasonable. Nevertheless, the main essence of the invention, viz., a roll up type retractable strap guide is not altered whether the operation is by automatic control means or entirely by manual means. In fact, it is also considered possible, although not as practical, to provide merely a hand crank on the drum shaft 22 which could accomplish the same purpose as the motor.

Although only a single embodiment of the invention has been shown and described, it should be understood that the invention can be made in many different ways without departing from the true scope of the invention, as defined by the appended claims.

I claim:

1. The combination in strapping apparatus, of support means for supporting a pallet of a type having a horizontal opening extending through it, a retractable sheet metal strap guide, and means for both retracting and extending the retractable stra guide through the horizontal opening of the pallet where it can guide a strap fed endwise through the opening, said strap guide being of concavo-convex cross section to impart rigidity to it so that it is self-supporting in cantilever and its concave side facing upward as a trough for guiding a strap fed endwise over it when the guide is in its extended position, the sheet metal from which the strap guide is made being flexible enough to allow the guide to be 'bent to follow a nonrectilinear path as the guide is extended and retracted, the sheet metal of the guide also being resilient enough to cause the guide to retain its concavo-convex cross section along its straight path portions, said means for re tracting and extending the retractable strap guide comprising a hub around which the strap guide is wrapped.

2. The combination in strapping apparatus, of support means for supporting a pallet of a type having a horizontal opening extending through it, a retractable sheet metal strap guide, and actuating means for retracting and extending the retractable strap guide through the horizontal opening of the pallet where it can guide a strap fed endwise through the opening, said strap guide being of concavo-convex cross section to impart rigidity to it so that it is self-supporting in cantilever and flexible enough to allow it to be bent into a coil, with the concave-convex cross section flattened and resilient enough to return to its original concavo-convex cross section when unwound from a coil shape, said actuating means for retracting and extending the retractable strap guide comprising coiling means around which the strap guide is wrapped into a coil.

3. The combination in strapping apparatus, of support means for supporting a pallet of a type having a horizontal opening extending through it, a retractable strap guide, and actuating means for retracting and extending the strap guide through the horizontal opening of the pallet where it can guide a strap fed endwise through the opening, said strap guide being of concave-convex cross section to impart rigidity to it so that it is self-supporting in cantilever and flexible enough to allow it to be bent into a coil with the concavoconvex cross section flattened and resilient enough to return it to its original concavoconvex cross section when unwound from a coil shape, said actuating means for retracting and extending the retractable strap guide including coiling means around which the strap guide is wrapped into a coil.

4. The combination in strapping apparatus according to claim 2 characterized by, and drive means for driving said coiling means for causing said retractable strap guide to be selectively coiled or uncoiled around said coiling means.

5. The combination in strapping apparatus according to claim 3 characterized by, and drive means for driving said coiling means for causing said retractable stra guide to be selectively coiled or uncoiled around said coiling means.

6. The combination in strapping apparatus, of support means for supporting a pallet of a type having a horizontal opening extending through it, a retractable strap guide, and actuating means for retracting and extending the strap guide through the horizontal opening of the pallet where it can guide a strap fed endwise through the opening, said strap guide being of concave-convex cross section to impart rigidity to it so that it is self-supporting in cantilever and flexible enough to allow it to be bent into a coil with the concavo-convex cross section flattened and resilient enough to return it to its original concavo-convex cross section when unwound from a coil shape, hub means around which the retractable strap guide can he wound into a coil, and drive means engaging the strap guide to drive it in one direction or the other in order to alternatively unwind it from and onto the hub means for extending and retracting it.

7. The combination in strapping apparatus according to claim 6 characterized by, said drive means having a driving belt engaging the stra guide in a region where it is wound into a coil, said belt driven by a prime mover.

8. The combination in strapping apparatus according to claim 6 characterized by, said hub means having stop means thereon for controlling the amount of extension and retraction of the retractable strap guide.

9. The combination in strapping apparatus according to claim 6 characterized by, said drive means including an electric motor as a prime mover for it, said hub means being mounted on a shaft which is rotated with said hub means as the retractable strap guide is extended and retracted, said shaft being threaded to threadedly engage a switch carrier which is moved longitudinally along said shaft as the shaft rotates, stop means being provided on said shaft for actuating switches mounted on said switch carrier, said switches being in an electrical circuit with said motor so that their actuation controls the actuation of the motor to thereby control the extension and retraction strokes of the retractable strap guide.

10 The combination in strapping apparatus according to claim 6 characterized by, said drive means including an electric motor as a prime mover for it, said hub means being mounted on a shaft which is rotated with said hub means as the retractable strap guide is extended and retracted, said shaft being threaded to threadedly engage a switch carrier which is moved longitudinally along said shaft as the shaft rotates, stop means being provided on said shaft for actuating switches mounted on said switch carrier, said switches being in an electrical circuit with said motor so that their actuation controls the actuation of the motor to thereby control the extension and retraction strokes of the retractable strap guide, said stop means being the ends of spaced apart helical springs wound onto said threaded shaft.

11. The combination in strapping apparatus according to claim 6 characterized by, said drive means having a driving belt engaging the strap guide in a region where it is wound into a coil and said belt being driven by an elec- 10 tric motor, said hub means having electrical switch means connected thereto for controlling the actuation of said electric motor and thereby control the amount of extension and retraction of the retractable strap guide.

12. The combination in strapping apparatus according to claim 6 characterized by, said drive means including an electric motor as a prime mover for it, said hub means being mounted on a shaft which is rotated with said hub means as the retractable strap guide is extended and retracted, said shaft being threaded to threadedly engage a switch carrier which is moved longitudinally along said shaft as the shaft rotates, stop means being provided on said shaft for actuating switches mounted on said switch carrier, said switches being in an electrical circuit with said motor so that their actuation controls the actuation of the motor to thereby control the extension and retraction strokes of the retractable strap guide, said stop means being the ends of spaced apart helical springs wound onto said threaded shaft, said helical springs being threadedly adjustable along said shaft in order to adjust the end positions of the retractable strap guide when it is extended and retracted.

References flirted in the file of this patent UNITED STATES PATENTS 2,236,136 Gorman Mar. 25, 1941 2,725,436 Crocker Nov. 29, 1955 2,780,986 Ritenour Feb. 12, 1957 2,831,422 Black et al Apr. 22, 1958

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