US2814327A - Serpentine tube bending machine with axially shiftable upper and lower clamping and bending die sections - Google Patents

Description

Nov. 26, 1957 H. H. CHARLTON SERPENTINE TUBE BENDING MACHINE WITH AXIALLY SHIFTABLE UPPER AND LOWER CLAMPING AND BENDING DIE SECTIONS 9 Sheets-Sheet 1 Filed Feb. 21, 1955 1a CLAMP UNCLAMP AND a FEED INITIAL POSITION TURN TUBE AND CLAMP N O m R H W V. B,

ATTORNEY Nov. 26, 1957 H. H. CHARLTON 2,814,327

SERPENTINE TUBE BENDING MACHINE WITH AXIALLY SHIFTABLE UPPER AND LOWER CLAMPING AND BENDING DIE SECTIONS 9 Sheets-Sheet 2 Filed Feb. 21, 1955 INVENTOR. v HARRY H.CHARLTON ATTORNEY Nov. 26, 1957 H. H. CHARLTON 2,814,327

SERPENTINE TUBE BENDING MACHINE WITH AXIALLY SHIFTABLE UPPER AND LOWER CLAMPING AND BENDING DIE SECTIONS Filed Feb. 21. 1955 9 Sheets-Sheet 5 INVENTOR. HARRY H.CHARLTON ATTOR NEY f BY 25, 1957 H. H. CHARLTON 2,81 27 SERPENTINE TUBE BENDING MACHINE WITH AXIALLY SHIFTABLE UPPER AND LOWER CLAMPING AND BENDING DIE SECTIONS 9 Sheets-Sheet 4 Filed Feb. 21. 1955 INVEN TOR. HARRY H. CHARLTON ATTORNEY 1957 H. H. CHARLTON 2,81 27 SERPENTINE TUBE BENDING MACHINE WITH AXIALLY SHIFTABLE UPPER AND LOWER CLAMPING AND BENDING DIE sscnous Filed Feb. 21. 1955 9 Sheets-Sheet 5 INVENTOR. HARRY H. CHARLTON BY v m MW ATTORNEY Nov. 26, 1957 H. H. CHARLTON SERPENTINE TUBE BENDING MACHINE WITH AXIALLY SHIFTABLE UPPER AND LOWER CLAMPING AND BENDING DIE SECTIONS 9 Sheehs-Sheer 6 Filed Feb 21, 1955 BENDING TABLE 3' J9 INVENTOR. HARRY H. ('JHARLTON BY W $4 ATTORNEY BLE Nov. 26, 1957 H. H. CHARLTON SERPENTINE TUBE BENDING MACHINE WITH AXIALLY SHIFTA UPPER AND LOWER CLAMPING AND BENDING DIE SECTIONS 9 Sheets-Sheet 7 Filed Feb. 21, 1955 JNVENTOR. HARRY H.CHARLTON mp6, 26W

ATTORNEY Nov. 26, 1957 H. H. CHARLTON 2,814,327

SERPENTINE TUBE BENDING MACHINE WITH AXIALLY SHIFTABLE UPPER AND LOWER CLAMPING AND.

BENDING DIE SECTIONS Filed Feb. 21, 1955 9 Sheets-Sheet s I4 '12 t I5 (66 '7! "5% l6 v67 68 69 v73 I I I9 r I" 2b 65 I 37 36 HUMAN IIUI- I f I r FIG. 24

FIG. 25

IN VEN TOR.

ATTO RNEY Nov. 26, 1957 H. H. CHARLTON 2,814,327

SERPENTINE TUBE BENDING MACHINE WITH AXIALLY SHIFTABLE UPPER AND LOWER CLAMPING AND BENDING DIE" SECTIONS Filed Feb. '21, 1955 9 Sheets-Sheet 9 2a Id 341 male? 2a 22 2 b 4 i: Q '36 Y Z (v I INVENTOR. 26 y HARRY H. CHARLTON ATTORNEY AXIALLY SHIFTABLE UPPER AND LOWER CLAMPING AND BENDING DIE SECTIONS Harry H. Charlton, Louisville, Ky., assignor to Reynolds Metals Company, Louisville, Ky a a corporation of Delaware Application February 21, 1955, Serial No. 489,622

9 Claims. (Cl. 153l-40) The present invention relates to an apparatus for bendingtubing or the like into sinuous form and more particularly relates to an apparatus and control mechanism therefor.

It is an object to provide a bending apparatus which automatically performs the bending operaton and feeds a length of material for the next bending operation,

A further objectis the provision of a bending apparatus which employs a rotatable clamping die for forming a bend, with provision for releasing the clamping action at the end of-the bending movement.

A further object is the provision of a bending apparatus embodying a simple mechanism for operating and controlling the clamping, unclamping, and bending movements.

Another object isthe provision of a bending apparatus of improved simple construction for transmitting rotary and translation movements to the bending die.

Still another object is the provision of a fluid control apparatus wherein the control of the bending apparatus and feeding mechanism therefor is carried out automatically in the proper. sequenee.

Another object is the provision of a bending apparatus employing a novel damping mechanism to prevent. whip of the material at the endsof the operating strokes.

The invention will be described indetail in thefollowing specification taken in connection with the accompanying drawing illustrating a preferred embodiment of the invention by way of example, and wherein:

Figures 1 to 5- are diagrammatic views showing the bending operations;

Figure 6 is a plan view of the bending apparatus with parts broken away;

Figure 7 is a. section taken on line VIIVII of Figure 6 with parts broken away;

Figure 8 is a fragmentary view similar to Figure 7 showing the dies in separated position;

Figure 9 is afragmentary. plan. view as. viewedon line IX;IX of Figure 7, withparts removed;

Figure 10 is a bottom view of the top, die section;

Figure 11 is a fragmentary section view showing mechanism omitted from the bottom of Figure 7 for raising the; shaft;

Figure 12 is a bottom view of the plate separated from the apparatus for, holding the upper die section;

Figure, 13 is a fragmentary side elevation view of Fi ure. 1] as seen from the right;

Figure 14 is'a fragmentary view showingthe head which carries the motor for operating the upper die section.

Figure 15 is a fragmentary section taken on line XV- XV of Figure 6;

Figure 16 is, a side elevation of a part of Figure 15, as viewed. from, the left;

Figure. 17 isa side, elevational view of the tube feeding mechanism with parts broken away;

Figure 18 isa elevational view of the feed head as seen ro h e t. of F ure, 7

Figure. IQ is aview. in vertieal; section on line.XlX-XIX of Figure 13';

atent 2,814,327 Patented Nov. 26, 1957 Figure 20 is. anelevational view taken on line XX-XX of Figure 6 of a control detail;

Figure 21 is a schematic view of the fluid control mechanism;

Figure 22 is an elevational view of the operating rack and damping controlcams;

Figure 23 is a top view ofthedamping control cam;

Figure 24is an elevational view of the apparatus posi tioned at the endof its movement ofbending a tube prior to returning to starting position and with the dies in a separated position Figure 25 is a plan; view of Figure 24;

Figure 26 is a fragmentary enlarged'section taken on lines 2626 of f Figure 2 5; and

Figure-27 is: a; fragmentary enlarged section taken on lines; 2727 of Figu e 251' General description of operation Referring'to the drawing, the cycle of operation will be explained in connectionwith-Figures 1 to 5. As shown inFigure l, a tube 1 who bent is suitably clamped in die 2, which has a rounded end 3, the die being suitably grooved along its. edgesat 4 to accommodate the tube. The. die then is rotated,- on its center 5 through about degrees, carrying theztube with it to the position shown in Figure 2 to produce a return bend 6. The first run 1a of the tube thus formed: may. be; of any suitable length, and ordinarily the lengthof; the first; run is not accurately gauged. The tube then is; unclamped and is fed out, as shown; ii -Figure 3; while the die returns to starting position as shown in,- Figure- 4, Then tube 1 is manually tu ned to the position; shown in Figure 5, is manually moved tothe right till the'bend16 engages stop 7, and the, tube is clamped; inthe die in readiness to make the n x b n Tghebending; die- 2is made in two. sections shown in Figures; 7V to 10. The upper section 2a (Figure 10) ha a quartenround groove 4a extending around the side and: rounded nose 3;, merging with a semicircular groove or socket 9o passing through clamping portion 10a at; the other; side of the die. The lower section of the die (Figure 9 has asimilar quarter round groove 4b extending .arouncl the side and rounded nose 3, merging with a semieirculap groove 9b passing through the comple mentar-y clamping-portion 10b. ofthe die. The tube 1 to be bent passes through the grooves. 9a, 9b between the dieswith the end: 1a, of the tube to be bent extending to the left; as shown in Figurei9.

Upper die operating mechanism Referring to Figure 6', the bender base frame 11 is suitably-constructed ofi structural angle iron and carries a top plate 12 having acentral opening 13 (Figure 7) therein Anoverhanging head 14 (Figures 6 and 14) secured to th Plate-12 carries a fluid motor 15, and the piston rod 16 (Figures7 and 14) extending from the motor has a circular stepped plate 17 attached thereto by a threaded stud- 18 A sleeve 19' threaded and locked onthe plate 17 has. an internal flange 21 which retains a lower plate 22 (Figures 7 8 and 12), a thrust ball bearing 2.;3; being located between the plates. The lower plate haste; dovetail groove 24 in which is received the dovetail boss 25-of the upper section 2a of the die.

Rotary table support.

A flanged sleeve26 (Figure 7) issecured in the central aperture 13, of top. plate 12, and, this sleeve supports a WQHQ-WifiifibhSkfiXQZ? m nte on ll bearing assemblies'.28; 2 8'. The; sleevel'lcarries a spur gear 29. keyed the eon and the; geanis held in; abutting relation towasher 31, by aeolian 32 threaded. on the end of sleeve 27 and suitably locked in; position. This sleeve 27 is rotated through about 180 degrees on the bearings 28, 28' by gear 29, which in turn is rotated by rack 33. At the top of sleeve 27 is a flange or head 34 having a reduced stem 35 about which is located the bracket 36 suitably bolted to the flange, and a table 37 is bolted to the bracket and is carried thereby.

Lower die operating mechanism A vertical shaft 38 is journalled within sleeve 27 for vertical sliding movement. A collar 39 is threaded and locked on the shaft 38 near the bottom, and a spring 41 in a recess in sleeve 27 acts against collar 39 to bias the shaft 38 downwardly. The upper end of sleeve 27 has an eccentric slot 42 in which is positioned a block 43 fixed to the lower die section 2b, the block and slot being slightly tapered vertically, and the block has an opening through which extends the reduced end 44 of shaft 38. The block is secured to the shaft by a pin 45. A guide pin 46 in the end of shaft 38 passes through circular holes in the two die sections 2a and 2b and is held in this shaft by pin 45, the upper end of pin 46 being flat as indicated at 46' and passing through an oval shaped aperture 47 in lower plate 22. This guide pin serves to align the die sections in their vertical movement, and as hereinafter will appear, causes the upper die section to rotate with the lower die section when the die sections are separated.

A bottom plate 48 (Figures 11 and 13) supports a fluid motor 49 and carries gibs 51 in which a wedge cam 52 is slideable, the cam being suitably connected to the piston rod 53 of the motor 49. A spacer 54 suitably fastened to the lower end 55 of shaft 38 straddles the upper inclined face of the cam, and a ball thrust bearing 56 is inserted between the spacer and collar 39. As shown in Figure 7 the shaft 38 is in raised position with the die sections 2a and 2b clamping a tube, not shown, therebetween. Wedge cam 52 has a sloping slot 50 therein which receives a pin 50 passing through spacer 54 and slot 50. Upon movement of the cam 52 by motor 49 to the right as shown in Figure 13, the cam 52 engaging spacer 54 moves the shaft 38 upwardly carrying with it the die 2b, and motor 15 is simultaneously operated to lower the upper die 2a to thus clamp the tube in the die. After the bending operation, motor 49 moves cam 52 to the left, and the engagement of pin 50' in slot 50 moves the shaft 38 and die 2b downwardly, while motor 15 simultaneously raises the upper die 2a.

As seen in Figures 6 and 7, the rack 33 which rotates gear 29, sleeve 27 and table 37, is operated by a piston rod 57 extending from motor 58, the guides for the rack being carried on a fixture 59 secured to bottom plate 48 (Fig. 13). Casters 61 (Fig. 6) secured on the bottom of table 37 bear on the circular bearing plate 12 of the table during rotary movement of the table.

Tube feeder A guide plate 62 (Figures 6 and 9) mounted on the top plate 12 is located in closely adjacent relation to the die 2 at the feed end with a projecting portion 63 in alignment with the grove 9b in the die. This guide plate prevents springing of the tube during bending and helps to produce a uniform curvature.

Referring to Figures 17 to 19, the apparatus for feeding the tube between bending operations comprises a V shaped feed trough 65 in which a length of tubing 1 to be bent is located, the trough being supported on suitable posts (post 65 shown). A fluid pressure motor 66 of a length to provide the desired feed stroke is supported on suitable posts 67, 68 connected to support 67' and has a piston rod 69 extending therefrom. The post 68 supports one end of a guide bar 71, the other end of the guide bar being carried on bracket 72 on head 14 (Figures 6 and 14), and this bar guides the movement of a cross head 73 secured to the piston rod. As shown in Figures 18 and 19 the cross head comprises a body having a recess 75 in which is suitably secured an angle bracket 76 which is apertured and provided a suitable tapered trough 77 to receive the tube to be bent. A pawl member 78 is pivoted at 79 in a recess 81 in the body, and as shown in Figure 19 the pawl is at its counterclockwise limit of movement. The pawl has a screw 82 which holds a tooth 83 in place, the tooth and screw being biased down against the tube by a spring 84. A set screw 85 acts against a fiat portion of screw 82 to prevent turning of the tooth and screw, but allows screw 82 to move vertically. It will be seen that when cross head 73 moves to the right as seen in Figures 17 and 19 the tooth 83 rides over the tube 1, but when the cross head moves to the left, the tooth 83 grips the tube and feeds the tube forward to the bender. A V bracket 86 supports the tube near the bending table. The stroke of the piston determines the length of the feed, and the stroke may be adjusted in any suitable manner.

Gauge Referring to Figure 6, near the leading edge of the table 37 is an elongated slot 87, and a housing 88 (Figures 15 and 16) is suitably attached beneath the table, the housing providing a boss 89 which extends up into slot 87. The housing is so fastened under the table that it may be adjusted along the slot 87. The stop or gauge pin 7 has a shoulder 91 so that the spring 92 in the housing tends to depress the pin, and an extension or plunger 93 extends below the closure plate 94. A cam 95 is secured to the top of plate 12 in such position that when the table is in the position shown in Figure 6 the plunger 93 is forced upward by cam 95, thus raising the stop pin 7 above the upper surface of the table 37. It will be seen that when the table starts to rotate clockwise the plunger 93 becomes free of the cam 95 so that spring 92 can depress stop pin 7. The stop pin 7 remains depressed until, in the return movement of the table, plunger 93 again engages cam 95, to raise the stop pin 7 against the action of the spring.

Detailed description of operation The operation of the apparatus so far described Will be explained. A length of tubing 1 to be bent, is inserted into the trough 65 (Figs. 17 and 6) from left to right, over a suitable mandrel that lies in the trough (not shown). In this initial position the portion 1a of the tube lies adjacent stop 7 (Fig. 1). Motors 15 and 49 then are actuated, the motor 15 causing the upper die section 2a to descent while motor 49 moves cam 52 to the right to raise shaft 38 and thus raise lower die section 2b to clamp the tube between clamping sections 10a and 1% (Fig. 8). Motor 58 then is actuated to move rack 33 to the right, thus rotating gear 29 and sleeve 27 clockwise. Because block 43 to which the lower die is connected is positioned in the slot 42 in sleeve 27, the lower die is caused to rotate, carrying with it the upper die because of the interlocking action of the tube in the die, and the table 37 secured to the sleeve by bracket 36 is rotated to support the end of the tube. The rotation of the die wraps the tube around the semicircular nose 3, the tube being free to feed out as required to allow formation of the bend. The stop pin 7 is merely an aligning pin for use in positioning the tube prior to moving the clamping die sections together and once the tube is clamped in the die sections, the pin no longer serves any function. When the table starts to turn in bending direction, the pluinger (Fig. 15) moves off the stationary cam 95 and the spring 92 depresses the stop pin 7 to prevent its interference with the tube during the return of the table and die sections to the starting position.

At the end of the bending movement (shown in Figs. 24 to 27), which is slightly more than degrees to allow for spring back of the tube, the motors 15 and 49 are reversed to separate the die sections and unclamp the tube. Motor 58 then is reversed, and as the dies have spread enough to allow the tube to pass between the mating plane faces of the die sections, the die and ism-32'? tube remains stationary. The. flat portion 46"onpin46 engages the slot 47 and causes the upper die to rotate with the lower die. At starting position cam 95raises stop 7' to. its operative position. The feed motor 66 is actuated when the reverse motion starts, and feeds the tube 1 through the die for a suflicient length to make the next bend- The feedneedn-ot be accurately regulated, and it is necessary to feed a greater length of tubing than required, because the bent portion of the tubing must clear the dies and the overhead sleeve 19 when the op-- erator manually flips over the bent tube to the position shown in Figure 5' and pushes the tube back to engage stop 7.

Fluid control mechanism The controlling devices for operating the various fluid pressure motors now will be described, in detail. It is to be observed that fluid motors 15 and; 49 aremanually operated to clamp the tubing in thedie, and thatfluid motor 58 is manually operated to start the bending operation. Referring to Figure 6, control .valves 97, ,98-and- 99 are provided at the front end of the apparatus,v the' valve 97 serving. to control the clamping movement of- motors 15 and 49, and valve 99 serves to control the, bending movement of motor 58. Valve98v isan: emergencyrvalve to operate motors 15 and 49 in unclamping, direction. The description of the control devices can be-further followed by reference to Figure 21.

A four way valve 101 is connectedby fluid conduit 102 to a manual control valve 97,.jby. fluid conduit 108 to a cam actuated valve 107,.and. by fluid conduits103, 104to clamp" operating motors 15, 49,. Depending on the position of four way valve 101,v one of lines. 103, 104 will supply positive pressure from high pressure line 105, while the other will exhaust by line 106, and the position of four way valve 101 depends on which conduit 102, 108 is connected to the positive pressure source. As shown, motors 15, 49 are in clamping position.

Motor 58 has conduits 112, 113 connected to four way valve 114, and one end of this four way valve has a conduit 115 connected through control valve 99 to the high pressure line 105. A conduit 118 connected to conduit 104 connects through open or closed valve 117 and conduit 116 to the other end of four way valve 114. Valve 117 is shown closed, and is opened when engaged by cam 119 on wedge cam 52 in the unclamped position. In open position of valve 117, pressure from conduit 104 can actuate four way valve 114. Either of conduits 112 or 113 may carry positive pressure, depending on the position of four way valve 114. As shown, motor 58 is ready to begin its working or bending stroke. At the end of its working stroke, cam 110 on rack 33 actuates the valve 107 to cause the valve 101 to supply pressure to the line 104 to move the motors 15, 49 to their un clamped positions.

The feed motor 66 has conduits 121, 122 connected to four way valve 123 which operates like valves 101 and 114. The valves 101, 114 and 123, as well as the other valves employed in the apparatus are commercially available, and therefore their mechanisms are not described in detail. One end of valve 123 is connected through open or closed valve 124 to positive pressure line 105, and the other end is connected through open or closed valve 124 to line 105'. As seen in Figures 6 and 14 valve 124 is mounted on head 14 adjacent rod 71 so that when the cross head 73 (Figure 17) reaches the end of its stroke the cam or bevel edge 126 engages the operating lever of valve 124 .to open this valve. Valve 124 is mounted under table 37 (Figure 6) near the end of the table stroke. As shown in Figures 6 and 20, a bracket 125' secured under table 37 carries a pivoted arm 130 biased by a spring 127 anchored at one end to post 128 extending from the table and attached at its other end to arm 130. rm 130 carries a cam 129 to rise 6 and" ride over the operating lever of'valve 124, buton the return stroke the. cam, 129. opens valve 124', thus operating four way valve 123 (Figure 21) to supply positive pressure by line 122 to motor 66 to feed a length of.

pipe to the die. Motor 66 is reversed when cam edge 126 opens valve 124.

A closed circuit conduit 131 connectingthe two tandem chambers of motor 58 includes a-normally open throttling valve 132. A bar 133 (Figures 22 and 23) attached to rack 33 carries cams 134, 135 and valve 132 is disposed between these cams so that, near the ends of the stroke of rack one of the cams will engage and throttle valve 132. Thus, by throttling the flow of fluid through closed circuit conduit 131 the movement of motor 58 near the end of each stroke is cushioned. This corresponds to the ends ofthe turning movement of table 37, and eliminates whipping action on the bent tube.

Operation The operation of the fluid control apparatus will now be described. In the position shown in Figure 21 clamp valve 97 has been operated to operate clamping motors 15 and 49, to hold the tube to be bent clamped in the die sections. Valve 99, thenis operated to cause rack 33 to move to the right and rotate the die sections and table 37 clockwise aspreviously described, and near the end of the movement of table 37 the valve 132 is throttled by can 134 to retard the table movement through the last ten degrees, more or less, of the stroke. The pivoted cam 129 rides over valve 124 on the clockwise rotation of the table, and at the; end of the table movement the chamferedcamedge.'110 on rack 33. operatesvalve 107 to con nect lines 111, 108 to reverse valve 101, and unclamp the die. Unclamping movement of motor 49 causes cam 119 to open valve 117 thus allowing the positive pressure now in line 104 to reverse valve 114 to reverse motor 58, which causes the table and die to move counter-clockwise. On the counter-clockwise movement cam 129 engages and opens valve 124', and thus valve 123 is operated to start the feed movement of motor 66. This feed movement is reversed when cam edge 126 engages and opens valve 124. The motor 58 meanwhile reaches the end of its return stroke, and the engagement of cam 135 with valve 132 retards the table movement. Near the end of the table movement plunger 93 engages cam to raise stop pin 7.

The operator then manually turns the tube on its axis and positions the tube against stop pin 7 in readiness to bend the next section, and when valve 97 is operated the motors 15, 49 return to the position shown in Figure 21 and cam 119 allows valve 117 to close, to place four way valve 114 under control of valve 99.

I claim as my invention:

1. A machine for bending tubing and the like comprising: a horizontal support; an axially movable vertically extending rotatable shaft mounted in said support; an upwardly open pocket in the top of said support into which the upper end of said shaft extends; a lower die section mounted on the upper end of said shaft to move therewith from a lowered unclamping position, in which position it is seated in said pocket, to a raised clamping position, said lower die section having a rounded nose and an adjacent clamping recess; a head mounted on said support over and spaced from said lower die section; an upper die section mounted on said head for free rotary movement and for vertical movement from a lowered clamping position to a raised unclamping position, said upper die section having a rounded nose and a clamping recess complementing said lower die section; means for moving said upper and lower die sections between said unclamping position, where said die sections are spaced apart, and said clamping position, where said die sections are in abutting relation to clamp a tube to be bent in said recesses; and means for rotating said shaft 7 to rotate said die sections conjointly in a direction to bend said tube about said rounded nose of said die sections.

2. A machine as specified in claim 1 having: a sleeve mounted for rotary movement on said support, said shaft being axially movable in said sleeve; means coupling said sleeve and shaft for conjoint rotation; and a table in substantially horizontal alignment with said lower die section mounted for rotation with said sleeve for supporting an end of said tubing during rotation of said die sections.

3. A machine as specified in claim 2 wherein: said table carries a retractible stop for gauging the length of tubing to be bent; and means for retracting said stop upon commencement of the rotating movement of said table in the bending direction.

4. A machine as specified in claim 1 wherein: said means for vertically moving said upper die section includes a reciprocatory fluid motor carried by said head andconnected to move said upper die section vertically, the upper die section being rotatably connected to said fluid motor.

5. An apparatus as specified in claim 1 wherein: said means for rotating said die sections comprises a fluid motor; a throttle valve connected to said fluid motor; and means operatively connected to said die sections rotating means for actuating said throttle valve near one end of the stroke of the fluid motor to retard the stroke of said motor.

6. An apparatus as specified in claim 1 wherein: said means for rotating said die sections comprises a fluid motor; and having means operated at the end of the bending stroke of the motor for moving said die sections to separated unclamping position.

7. A machine as specified in claim 6 having: a member on the lower die section forming an interlocking engagement with the upper die section when said die sections are in separated position.

, 8. An apparatus as specified in claim 1 having: means for reversing said last mentioned means to reverse rotation of said die sections; means for moving said die sections to unclamping position at the end of the bending rotation and prior to reverse rotation; feeding means for advancing a length of tubing through said die sections; and means operative during reverse rotation of said die sections to actuate said feeding means.

9. An apparatus as specified in claim 8 wherein said last mentioned means comprises a retractible cam rotated with said die sections; and a control member located to be engaged by said cam during reverse rotation thereof.

References Cited in the file of this patent UNITED STATES PATENTS 897,676 Thompson Sept. 1, 1908 1,007,377 Nielsen Oct. 31, 1911 1,052,069 Lassiter Feb. 4, 1913 1,267,845 Burt May 28, 1918 1,502,633 Holmgreen July 22, 1924 1,546,147 Skinner July 14, 1925 1,966,378 Dinzl July 10, 1934 2,126,235 Wesley Aug. 9, 1938 2,156,146 Chamberlin Apr. 25, 1939 2,305,266 Lincoln Dec. 15, 1942 2,430,217 Eastes Nov. 4, 1947 2,452,050 Hayward Oct. 26, 1948 2,453,868 Shaw Nov. 16, 1948 2,565,940 Armstrong Aug. 28, 1951 2,626,449 Montgomery Jan. 27, 1953 2,646,617 Turoif July 28, 1953 2,695,096 Gridley Nov. 23, 1954

Images