PATTERN SELECTION SYSTEM
United States Patent 3786769
A pattern cam selecting mechanism which is operated by turning movement of a dial and includes a cam follower retracting linkage effective during the angular movement of the dial between positions in which the various pattern cams are selected. The cam follower retracking linkage is constructed so as to utilize in either direction of dial movement much more than half the angular movement of the dial between successive positions of cam selection for retracting the cam follower. As a result, the magnitude of forces required to effect cam selection may be reduced or for the same magnitude of forces, a smaller angle of turning movement of the cam selecting dial need be required.
US Patent References:
Zigzag sewing machine with fancystitch selector
Engel - July 1962 - 3043252
Cam controlling mechanism in a pattern stitch sewing machine
Ohira - June 1965 - 3188991
Device for automatic selection of disc cams for composite zigzag patterns in sewing machines
Yanagibayashi - September 1967 - 3339508
PATTERN CAM SELECTING ARRANGEMENT
Hanyu - March 1969 - 3433092
Zigzag sewing machine with fancystitch selector
Engel - July 1962 - 3043252
Cam controlling mechanism in a pattern stitch sewing machine
Ohira - June 1965 - 3188991
Device for automatic selection of disc cams for composite zigzag patterns in sewing machines
Yanagibayashi - September 1967 - 3339508
PATTERN CAM SELECTING ARRANGEMENT
Hanyu - March 1969 - 3433092
Application Number:
05/329499
Publication Date:
01/22/1974
Filing Date:
02/05/1973
View Patent Images:
Export Citation:
Assignee:
The Singer Company (New York, NY)
Primary Class:
Other Classes:
112/465
International Classes:
D05B19/00; D05B3/02
Field of Search:
112/158R,158A,158B,158C
Primary Examiner:
Schroeder, Werner H.
Attorney, Agent or Firm:
Breen Jr., Marshall Williams Chester Smith Robert J. A. E.
Claims:
Having set forth the nature of this invention, what is claimed herein is
1. In a sewing maching machine having a plurality of pattern cams arranged co-axially in a stack, mechanisms including a cam follower responsive to any selected one of said pattern cams for influencing operation of said sewing machine, and cam selecting mechanism comprising a control dial journalled in said sewing machine, means responsive to a predetermined increment of turning of said control dial for shifting the tracking relationship of said cam follower from one to another of said plurality of pattern cams, means on said control dial for retracting said cam follower out of tracking relationship with said cam during substantially greater than half of each of said predetermined increments of control dial turning movement required for cam selection, said last named means comprising a cam follower retracting link operatively connected to said cam follower and shiftably supported for movement along a line extending substantially radially of said control dial, an abutment member pivotally supported on said link for limited swinging movement on each side of said line, substantially symmetrical sidewalls formed on said abutment member, and lobe means formed on said control dial and arranged for cooperation with said abutment member sidwalls upon turning of said control dial.
2. In a sewing machine as set forth in claim 1 in which the sidewalls of said abutment member each extending to an apex symmetrical on each side of said abutment member, and said lobe on said control dial is flanked by additional lobes, each of said lobes bring spaced apart an angle equal to said predetermined increment of turning of said control dial for shifting the tracking relation of said cam follower from one to another of said pattern cams.
3. In a sewing machine as set forth in claim 2 in which said abutment member is formed with a control notch founded by symetrical sidewalls, in which those of said symetrical sidewalls which diverge from said control notch and extend to the apex of said protuberances cooperate with said control member lobes to position the cam follower retracting link when the cam follower is disposed in tracking relation with one of said pattern cams, and in which those of said symetrical sidewalls which extend outwardly from said protuberance apexes cooperate with said control member lobes to position said cam follower retracting link in the retracted position thereof.
1. In a sewing maching machine having a plurality of pattern cams arranged co-axially in a stack, mechanisms including a cam follower responsive to any selected one of said pattern cams for influencing operation of said sewing machine, and cam selecting mechanism comprising a control dial journalled in said sewing machine, means responsive to a predetermined increment of turning of said control dial for shifting the tracking relationship of said cam follower from one to another of said plurality of pattern cams, means on said control dial for retracting said cam follower out of tracking relationship with said cam during substantially greater than half of each of said predetermined increments of control dial turning movement required for cam selection, said last named means comprising a cam follower retracting link operatively connected to said cam follower and shiftably supported for movement along a line extending substantially radially of said control dial, an abutment member pivotally supported on said link for limited swinging movement on each side of said line, substantially symmetrical sidewalls formed on said abutment member, and lobe means formed on said control dial and arranged for cooperation with said abutment member sidwalls upon turning of said control dial.
2. In a sewing machine as set forth in claim 1 in which the sidewalls of said abutment member each extending to an apex symmetrical on each side of said abutment member, and said lobe on said control dial is flanked by additional lobes, each of said lobes bring spaced apart an angle equal to said predetermined increment of turning of said control dial for shifting the tracking relation of said cam follower from one to another of said pattern cams.
3. In a sewing machine as set forth in claim 2 in which said abutment member is formed with a control notch founded by symetrical sidewalls, in which those of said symetrical sidewalls which diverge from said control notch and extend to the apex of said protuberances cooperate with said control member lobes to position the cam follower retracting link when the cam follower is disposed in tracking relation with one of said pattern cams, and in which those of said symetrical sidewalls which extend outwardly from said protuberance apexes cooperate with said control member lobes to position said cam follower retracting link in the retracted position thereof.
Description:
BACKGROUND OF THE INVENTION
Prior devices, such as that disclosed in the U.S. Pat. No. 3,043,252, July 10, 1962 of W. Engel utilizing a rotatable dial for both pattern cam selection and cam follower retraction between successive pattern cams, have not included any means for decreasing the force requirements of the follower retraction mechanism.
Particularly in instances in which only a small segment of the control dial periphery is exposed, such reduction of the required forces as is provided by the present invention is of a decided advantage in that, by use thereof, the angle of control dial movement which is required for each cam selection may be minimized. This results from the fact that it is desirable always to display to the operator the entire range of possible cam selections. Where only a portion of the control dial periphery is exposed, the ability materially to decrease the angle of dial movement required between cam selections is, therefore, important in providing a greater number of different cam selections which may simultaneously be displayed the view of the operator.
BRIEF SUMMARY OF THE INVENTION
It is an object of this invention to provide a cam selecting mechanism with an associated cam follower retracting mechanism operated during turning movement of the control dial between cam selection positions, in which in either direction of dial movement an appreciably greater portion of the total increment of dial movement is utilized to retract the follower than is devoted to permitting the follower to return into cam tracking relation. This object of the invention is obtained by the provision of a laterally shiftable abutment block on the follower retracting linkage together with stop means restricting the abutment block to lost motion within predetermined limits so that driving elements on the control dial can cooperative with slopes of much lower gradient on the abutment block for retracting the cam follower without requiring an increase of the increment of the control dial movement.
DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, a preferred embodiment of this invention is illustrated in which:
FIG. 1 represents a top plan view of a sewing machine having a pattern cam selecting mechanism including my invention applied thereto shown in a position of readiness for sewing with completed pattern cam selection,
FIG. 2 is a front elevational view of the mechanism of FIG. 1,
FIG. 3 is a top plan view of the cam follower retracting mechanism showing the cam follower held in retracted position during cam selection,
FIG. 4 is a perspective view of the cam selecting mechanism of this invention, and
FIG. 5 is an enlarged top plan view of a fragment of the cam follower retracting mechanism showing in solid lines the completed pattern cam selected position of parts, showing in dashed lines the cam follower retracted position of parts when the abutment block is prevented from shifting laterally, and showing in dashed-dotted lines the cam follower retracted position of parts with the laterally shifted abutment block shown at an exaggerated angle more clearly to illustrate this invention.
Referring particularly to FIGS. 1 and 2 of the drawings, a portion of the frame 11 of a sewing machine is illustrated in which is journaled a main drive shaft 12 of the sewing machine. By means of a crank 13 on the main drive shaft, operative movements are imparted to a needle thread take-up device 14 and endwise reciprocation is imparted to a needle carrying bar 15. The needle bar is reciprocated in a gate 16 which is fulcrummed in the machine frame so that the needle bar may be jogged laterally to produce zigzag stitches. A drive link 17 pivoted at 18 to the needle bar gate serves to impart jogging motion to the needle bar from a zigzag actuating mechanism indicated generally at 20 in the drawing.
The zigzag actuating mechanism 20 includes an oscillating bracket 30 pivoted to swing about a pivot pin 31 carried by a lever 32 having a fulcrum 33 in the machine frame. The needle bar drive link 17, which is biased towards the left as viewed in FIG. 2 by a spring 42 stretched between the drive link 17 and the machine frame 11, carries a slide block 43 which engages the right hand side of the oscillating bracket 30 as viewed in FIG. 2. A crank pin 44 carried by a bight adjusting dial 45 in the machine frame is embraced by a slot 46 in the needle bar drive link 17 and serves to shift the slide block 43 along the oscillating bracket relatively to to the pivot pin 31 thereof in order to regulate the bight of zigzag stitches. A linkage 47, 48 connects the lever 32 with a needle position adjusting dial 49 in the machine frame by which the needle position to the right, center, or left of the field of zigzag stitches may be regulated.
Fixed transversly through an ear 50 in the oscillating bracket 30 is a vertical pin 51. The pin 51 and the fulcrum pin 33 for the oscillating bracket define parallel guide rods on which a follower member 52 is vertically adjustable. The follower member 52, which includes an apertured arm 53 slidable embracing the fulcrum pin 33 and the bifurcated arm 54 slidable embracing the vertical pin 51, is formed with an upstanding arm 55 terminating in a cam follower finger 56. The follower member 52 is thus vertically shiftable so that the follower finger may be selectively positioned in tracking relationship with one of three needle jogging pattern cams 57, 58, or 59 carried on a cam shaft 60 journaled in the machine frame 11. The cam shaft 60 carries a worm wheel 61 meshing with a worm 62 on the main drive shaft 12.
An additional pattern cam 65 may be provided on the cam shaft for controlling the work feed movements. Since this cam and the associated follower mechanism 66 for influencing the work feed mechanism of the sewing machine do not form a direct part of this invention, they will not be described in further detail herein.
Selection of a pattern cam by the mechanism of this invention is regulated by a control dial 70 journaled on a shouldered screw 71 in the machine frame 11. As shown in FIG. 4, the dial 70 protrudes through the exterior 72 of the machine frame and carries a radial mark 73 which cooperates with indicia 74 on the machine frame to indicate the particular stitch pattern selected. In order for the mark 73 to remain visable in all possible cam selected positions, the dial must be arranged to protrude sufficiently beyond the machine frame, and the greater the angular movement which is required for cam selection, the greater the dial must protrude. Since the amount of the dial protrudes should advantagously be minimized for reasons of ascetic appearance as wll as questions of space limitations in cabinets, carrying cases, and the like, the feature of this invention by which the angular increment of turning movement of the dial necessary to effect cam selection is minimized becomes of considerable importance.
The position of the cam follower finger 56 along the cam shaft 60 is influenced by means of a cam ramp 80 arranged adjacent the periphery of the dial 70 and including an upwardly facing cam track 81 along which are formed three levels 82 each arranged at a different distance axially from the face of the control dial 70. The cam track 81 is engaged by a follower pin 83 secured as by a lock nut 84 to a follower lever 85 fulcrummed on a pin 86 relatively to the machine frame. The follower lever 85 is formed with a bifurcated extremity 87 which embraces the fulcrum pin 33 along which the follower member 52 is slidably arranged. The apertured arm 53 of the follower member 52 is arranged beneath the bifurcated extremity 87 and is biased upwardly against the follower level by a coil spring 88 which acts to urge the follower member upwardly causing the follower 56 to respond to the influence of the selection lever 85.
A detent spring 90 secured on the sewing machine frame engages the peripheral edge of the dial 70 and cooperates with detent notches 91 therein to define the three cam selected positions of the control dial 70.
For retracting the cam follower 56 during pattern cam selection so that the follower finger will not interfere with axial shifting movement relatively to the pattern cams, a cam follower retracting mechanism is provided. The cam follower retracting linkage includes a connecting link 100 which is slidably pivoted on the shouldered screw 71 on which the control dial 70 is pivoted and which at the opposite extremity is formed with an elongate slot 101 which straddles the vertical pin 51 in the oscillating bracket 30. Pivoted on a pin 102 in the connecting link 100 is a laterally movable abutment block 103. The abutment block 103 carries a stop pin 104 which protrudes into a clearance slot 105 formed in the connecting link 100 thus limiting the turning movement of the abutment block relatively the connecting link.
The abutment block 103 is formed with a central notch 106 bounded on each side by symetrical protuberances 107 defined by straight sidewalls 108 which diverge from the central notch and extend to apexes 109 of the protuberances. Outwardly of the apexes 109 each of the protuberances 107 is formed with a straight sidewall 110 similarly symetrical about the central notch 106. The protuberances 107 of the abutment block 103 cooperate with three equally spaced actuator lobes 111 which are formed on the control dial 70 equally distant from the axis of the control dial as defined by the shouldered screw 71. When the control dial 70 is turned, one of the actuator lobes 111 will be moved inwardly along one of the protuberance sidewalls 110 until it reaches the apex 109 of the protuberance 107 in which position the cam follower will be fully retracted. Continued turning of the control dial 70 will move the lobe 111 down the opposite sidewall 108 of the protuberance 107 and in so doing it will permit the abutment block 103 to return and re-establish tracking relation of the cam follower. This shifting movement of the connecting link 100 will effect a retraction of the follower finger 56 outwardly away from the periphery of the pattern cams 57, 58, and 59 during cam selection.
The maximum angular position which can be tolerated for the sidwalls 110 of the protuberances 107 with respect to the lobes 111 depends upon the distribution of forces which act upon the parts when the lobes 111 are shifted. By reducing the gradient of the sidewalls 110 the force necessary to turn the control dial 70 will be decreased, however such reduction of the angles will ordinarily result in a need for increase in the angular movement of the control dial required to influence cam selection. Moreover, it was heretofore necessary that only half of the total angular increment of control dial movement be devoted to shifting the cam follower away from the cam because cam selection back and forth in opposite directions must be provided for and therefore, the forces could not be eased in one direction at the expense of an increase in the forces when selecting in the opposite direction.
In the present invention, the lateral motion which is provided for the abutment block 103 by the pivot pin 102 which connects the abutment block to the connecting link 100 and the stop pin 104 which works in the clearance slot 105, provides for a considerable decrease in the effective slope of the sidewalls 110 of to protuberances 107 and a decrease in the forces generated by the action of the actuator lobes 111 therein. The reason for this result might best be explained with reference to FIG. 5 which shows in solid lines the position of the abutment block and an actuator lobe 111 in the at rest position of the device; that is, when the follower finger 56 is fully engaged with a cam on the cam shaft of the machine.
Shown in dashed lines in FIG. 5 is the relationship between the actuator lobe 111 and the sidewall 110 of protuberance 107 when the abutment block 103 is prevented from partaking of any lateral motion. It will be noted that the angle A which the actuator lobe 111 partakes in fully retracting the cam follower is one half the total increment of angular movement from one cam selected position to another. The dimension B indicates the total sliding movement imparted to the abutment member 103.
Shown in dashed and dotted lines in FIG. 5 is the relationship of parts when the abutment block 103 is permitted to partake of lateral motion. It will be noted that the angular movement A which the actuator lobe 111 partakes in retracting the cam follower is increased as has the dimension B of total sliding the movement of the abutment block 103. At the same time the angle which the actuator lob 111 makes with the sidewall 110 of the protuberance 107 is reduced by the lateral turning of the abutment block 103. The result of the arrangement of this invention is to devote a greater portion of the angular motion of the control dial during cam selection for retraction of the cam follower and a correspondingly reduce the portion of the total motion which is devoted to return of the cam follower back into tracking relation with the pattern cam. Because the abutment block 103 is free to shift laterally to either side of the connecting link 100, the increase in the portion of the turning segment which is devoted to cam retraction is effected in either direction of cam selection.
Prior devices, such as that disclosed in the U.S. Pat. No. 3,043,252, July 10, 1962 of W. Engel utilizing a rotatable dial for both pattern cam selection and cam follower retraction between successive pattern cams, have not included any means for decreasing the force requirements of the follower retraction mechanism.
Particularly in instances in which only a small segment of the control dial periphery is exposed, such reduction of the required forces as is provided by the present invention is of a decided advantage in that, by use thereof, the angle of control dial movement which is required for each cam selection may be minimized. This results from the fact that it is desirable always to display to the operator the entire range of possible cam selections. Where only a portion of the control dial periphery is exposed, the ability materially to decrease the angle of dial movement required between cam selections is, therefore, important in providing a greater number of different cam selections which may simultaneously be displayed the view of the operator.
BRIEF SUMMARY OF THE INVENTION
It is an object of this invention to provide a cam selecting mechanism with an associated cam follower retracting mechanism operated during turning movement of the control dial between cam selection positions, in which in either direction of dial movement an appreciably greater portion of the total increment of dial movement is utilized to retract the follower than is devoted to permitting the follower to return into cam tracking relation. This object of the invention is obtained by the provision of a laterally shiftable abutment block on the follower retracting linkage together with stop means restricting the abutment block to lost motion within predetermined limits so that driving elements on the control dial can cooperative with slopes of much lower gradient on the abutment block for retracting the cam follower without requiring an increase of the increment of the control dial movement.
DESCRIPTION OF THE DRAWINGS
In the accompanying drawings, a preferred embodiment of this invention is illustrated in which:
FIG. 1 represents a top plan view of a sewing machine having a pattern cam selecting mechanism including my invention applied thereto shown in a position of readiness for sewing with completed pattern cam selection,
FIG. 2 is a front elevational view of the mechanism of FIG. 1,
FIG. 3 is a top plan view of the cam follower retracting mechanism showing the cam follower held in retracted position during cam selection,
FIG. 4 is a perspective view of the cam selecting mechanism of this invention, and
FIG. 5 is an enlarged top plan view of a fragment of the cam follower retracting mechanism showing in solid lines the completed pattern cam selected position of parts, showing in dashed lines the cam follower retracted position of parts when the abutment block is prevented from shifting laterally, and showing in dashed-dotted lines the cam follower retracted position of parts with the laterally shifted abutment block shown at an exaggerated angle more clearly to illustrate this invention.
Referring particularly to FIGS. 1 and 2 of the drawings, a portion of the frame 11 of a sewing machine is illustrated in which is journaled a main drive shaft 12 of the sewing machine. By means of a crank 13 on the main drive shaft, operative movements are imparted to a needle thread take-up device 14 and endwise reciprocation is imparted to a needle carrying bar 15. The needle bar is reciprocated in a gate 16 which is fulcrummed in the machine frame so that the needle bar may be jogged laterally to produce zigzag stitches. A drive link 17 pivoted at 18 to the needle bar gate serves to impart jogging motion to the needle bar from a zigzag actuating mechanism indicated generally at 20 in the drawing.
The zigzag actuating mechanism 20 includes an oscillating bracket 30 pivoted to swing about a pivot pin 31 carried by a lever 32 having a fulcrum 33 in the machine frame. The needle bar drive link 17, which is biased towards the left as viewed in FIG. 2 by a spring 42 stretched between the drive link 17 and the machine frame 11, carries a slide block 43 which engages the right hand side of the oscillating bracket 30 as viewed in FIG. 2. A crank pin 44 carried by a bight adjusting dial 45 in the machine frame is embraced by a slot 46 in the needle bar drive link 17 and serves to shift the slide block 43 along the oscillating bracket relatively to to the pivot pin 31 thereof in order to regulate the bight of zigzag stitches. A linkage 47, 48 connects the lever 32 with a needle position adjusting dial 49 in the machine frame by which the needle position to the right, center, or left of the field of zigzag stitches may be regulated.
Fixed transversly through an ear 50 in the oscillating bracket 30 is a vertical pin 51. The pin 51 and the fulcrum pin 33 for the oscillating bracket define parallel guide rods on which a follower member 52 is vertically adjustable. The follower member 52, which includes an apertured arm 53 slidable embracing the fulcrum pin 33 and the bifurcated arm 54 slidable embracing the vertical pin 51, is formed with an upstanding arm 55 terminating in a cam follower finger 56. The follower member 52 is thus vertically shiftable so that the follower finger may be selectively positioned in tracking relationship with one of three needle jogging pattern cams 57, 58, or 59 carried on a cam shaft 60 journaled in the machine frame 11. The cam shaft 60 carries a worm wheel 61 meshing with a worm 62 on the main drive shaft 12.
An additional pattern cam 65 may be provided on the cam shaft for controlling the work feed movements. Since this cam and the associated follower mechanism 66 for influencing the work feed mechanism of the sewing machine do not form a direct part of this invention, they will not be described in further detail herein.
Selection of a pattern cam by the mechanism of this invention is regulated by a control dial 70 journaled on a shouldered screw 71 in the machine frame 11. As shown in FIG. 4, the dial 70 protrudes through the exterior 72 of the machine frame and carries a radial mark 73 which cooperates with indicia 74 on the machine frame to indicate the particular stitch pattern selected. In order for the mark 73 to remain visable in all possible cam selected positions, the dial must be arranged to protrude sufficiently beyond the machine frame, and the greater the angular movement which is required for cam selection, the greater the dial must protrude. Since the amount of the dial protrudes should advantagously be minimized for reasons of ascetic appearance as wll as questions of space limitations in cabinets, carrying cases, and the like, the feature of this invention by which the angular increment of turning movement of the dial necessary to effect cam selection is minimized becomes of considerable importance.
The position of the cam follower finger 56 along the cam shaft 60 is influenced by means of a cam ramp 80 arranged adjacent the periphery of the dial 70 and including an upwardly facing cam track 81 along which are formed three levels 82 each arranged at a different distance axially from the face of the control dial 70. The cam track 81 is engaged by a follower pin 83 secured as by a lock nut 84 to a follower lever 85 fulcrummed on a pin 86 relatively to the machine frame. The follower lever 85 is formed with a bifurcated extremity 87 which embraces the fulcrum pin 33 along which the follower member 52 is slidably arranged. The apertured arm 53 of the follower member 52 is arranged beneath the bifurcated extremity 87 and is biased upwardly against the follower level by a coil spring 88 which acts to urge the follower member upwardly causing the follower 56 to respond to the influence of the selection lever 85.
A detent spring 90 secured on the sewing machine frame engages the peripheral edge of the dial 70 and cooperates with detent notches 91 therein to define the three cam selected positions of the control dial 70.
For retracting the cam follower 56 during pattern cam selection so that the follower finger will not interfere with axial shifting movement relatively to the pattern cams, a cam follower retracting mechanism is provided. The cam follower retracting linkage includes a connecting link 100 which is slidably pivoted on the shouldered screw 71 on which the control dial 70 is pivoted and which at the opposite extremity is formed with an elongate slot 101 which straddles the vertical pin 51 in the oscillating bracket 30. Pivoted on a pin 102 in the connecting link 100 is a laterally movable abutment block 103. The abutment block 103 carries a stop pin 104 which protrudes into a clearance slot 105 formed in the connecting link 100 thus limiting the turning movement of the abutment block relatively the connecting link.
The abutment block 103 is formed with a central notch 106 bounded on each side by symetrical protuberances 107 defined by straight sidewalls 108 which diverge from the central notch and extend to apexes 109 of the protuberances. Outwardly of the apexes 109 each of the protuberances 107 is formed with a straight sidewall 110 similarly symetrical about the central notch 106. The protuberances 107 of the abutment block 103 cooperate with three equally spaced actuator lobes 111 which are formed on the control dial 70 equally distant from the axis of the control dial as defined by the shouldered screw 71. When the control dial 70 is turned, one of the actuator lobes 111 will be moved inwardly along one of the protuberance sidewalls 110 until it reaches the apex 109 of the protuberance 107 in which position the cam follower will be fully retracted. Continued turning of the control dial 70 will move the lobe 111 down the opposite sidewall 108 of the protuberance 107 and in so doing it will permit the abutment block 103 to return and re-establish tracking relation of the cam follower. This shifting movement of the connecting link 100 will effect a retraction of the follower finger 56 outwardly away from the periphery of the pattern cams 57, 58, and 59 during cam selection.
The maximum angular position which can be tolerated for the sidwalls 110 of the protuberances 107 with respect to the lobes 111 depends upon the distribution of forces which act upon the parts when the lobes 111 are shifted. By reducing the gradient of the sidewalls 110 the force necessary to turn the control dial 70 will be decreased, however such reduction of the angles will ordinarily result in a need for increase in the angular movement of the control dial required to influence cam selection. Moreover, it was heretofore necessary that only half of the total angular increment of control dial movement be devoted to shifting the cam follower away from the cam because cam selection back and forth in opposite directions must be provided for and therefore, the forces could not be eased in one direction at the expense of an increase in the forces when selecting in the opposite direction.
In the present invention, the lateral motion which is provided for the abutment block 103 by the pivot pin 102 which connects the abutment block to the connecting link 100 and the stop pin 104 which works in the clearance slot 105, provides for a considerable decrease in the effective slope of the sidewalls 110 of to protuberances 107 and a decrease in the forces generated by the action of the actuator lobes 111 therein. The reason for this result might best be explained with reference to FIG. 5 which shows in solid lines the position of the abutment block and an actuator lobe 111 in the at rest position of the device; that is, when the follower finger 56 is fully engaged with a cam on the cam shaft of the machine.
Shown in dashed lines in FIG. 5 is the relationship between the actuator lobe 111 and the sidewall 110 of protuberance 107 when the abutment block 103 is prevented from partaking of any lateral motion. It will be noted that the angle A which the actuator lobe 111 partakes in fully retracting the cam follower is one half the total increment of angular movement from one cam selected position to another. The dimension B indicates the total sliding movement imparted to the abutment member 103.
Shown in dashed and dotted lines in FIG. 5 is the relationship of parts when the abutment block 103 is permitted to partake of lateral motion. It will be noted that the angular movement A which the actuator lobe 111 partakes in retracting the cam follower is increased as has the dimension B of total sliding the movement of the abutment block 103. At the same time the angle which the actuator lob 111 makes with the sidewall 110 of the protuberance 107 is reduced by the lateral turning of the abutment block 103. The result of the arrangement of this invention is to devote a greater portion of the angular motion of the control dial during cam selection for retraction of the cam follower and a correspondingly reduce the portion of the total motion which is devoted to return of the cam follower back into tracking relation with the pattern cam. Because the abutment block 103 is free to shift laterally to either side of the connecting link 100, the increase in the portion of the turning segment which is devoted to cam retraction is effected in either direction of cam selection.