US2745525A - Electric transmitter for sewing machines - Google Patents

Description

May 15, 1956 A. N. HALE 2,745,525

ELECTRIC TRANSMITTER FOR SEWING MACHINES Filed July 23, 1954 4 Sheets-Sheet 1 May 15, 1956 A. N. HALE ELECTRIC TRANSMITTER FOR SEWING MACHINES 4 Sheets-Sheet 2 FIG.2

Illlllll to 1 l I y 1956 A. N. HALE 2,745,525

ELECTRIC TRANSMITTER FOR SEWING MACHINES Filed July 23, 1954 4 Sheets-Sheet 5 33 IIIIII'IIIIII May 15, 1956 A. N. HALE 2,745,525

ELECTRIC TRANSMITTER FOR SEWING MACHINES Filed July 23, 1954 4 Sheets-Sheet 4 United States Patent ELECTRIC TRANSMITTER F OR SEWIN MACHINES Arthur N. Hale, Park Ridge, 11]., assignor to Union Special Machine Company, Chicago, Ill., a corporation of Illinois Application July 23, 1954, Serial No. 445,276

12 Claims. (Cl. 192-35) This invention relates to an electric power unit for driving a sewing machine. The unit comprises an electric motor, a flywheel and a clutch, with novel connections between these elements which adapt the unit for high speed operation of a sewing machine.

For eflicient and uniform operation of a sewing machine it is desirable to provide a power source which is capable of quick acceleration and deceleration of the machine and which will operate the machine at a substantially uniform speed throughout a stitch forming operation, regardless of variations in the load in the course of forming a seam. To achieve the latter result it has been considered desirable to employ an induction motor, and in order to attain a maximum speed this is usually of the two pole type. Such motors operating on 60 cycle alternating current have a theoretical speed of 3,600 R. P. M. but a rated speed of about 3,450 R. P. M.

The importance of quick acceleration and deceleration will be appreciated when it is considered that a sewing machine is subject to very frequent starting and stopping. Only a few seconds are required to form a seam of average length. Therefore, little benefit would be derived from a machine capable of maximum operation at, say, 5,000 R. P. M., if a large portion of the time is consumed in getting up to speed. With the present trend toward higher and higher speeds the importance of rapid acceleration to the normal high speed is accentuated. For good elficiency in the operation of a sewing machine it is desirable to bring the machine to substantially its maximum operating speed within about A of a second. Even more rapid acceleration is desirable. In general, it has been found that a machine may be gotten up to around 90% of its maximum speed within to 30 hundredths of a second, depending upon the machine and its driving means. From this point the machine more gradually increases in speed to its maximum. Factors which enter into the problem of acceleration are the characteristics of the machine itself contributing to inertia, the inertia of the clutch plate and driving pulley of the power unit, the type of belt employed to connect the power unit with the machine, the belt tension, and the like.

To attain machine speeds above 5,000 R. P. M. with present power units, so-called electric transmitters, it has become necessary to increase the size of the motor pulley .in relation to the machine pulley. However, this has led to belt slippage, due to the smaller arc of contact with the machine pulley, and has thus increased the length of time required to bring the machine substantially to its maximum speed. This condition becomes quite objectionable when the pulley diameters are such that the machine is operated at more than about one and a half times the speed of the motor.

It has been a primary object of the present invention to provide a'power unit capable of bringing a sewing machine driven thereby up to substantially its maximum speed within a minimum of time, say within A of a second or even less.

A further object has been to provide a unit of the fore- Patented May 15, 1956 going character which will operate the sewing machine at substantially its maximum speed for the major portion of its operation in forming a seam, without fluctuation as a result of variations in the load incident to the formation of the seam. This is important to the production of substantially uniform stitches.

Toward the foregoing ends the new power unit has a single speed motor, preferably a two pole induction motor having a rated speed of 3,450 R. P. M. The shaft of this motor is connected through step-up gearing with a shaft which carries a flywheel. This is preferably driven at an angular speed of about 1.5 times the speed of the motor shaft and, therefore, a flywheel of given weight is capable of overcoming substantially higher inertia of the driven parts. If desired, a smaller or lighter flywheel may be employed in accordance with the invention than that now usually employed and still provide improved acceleration of the driven machine, due to improved belt contact.

A further feature of the new power unit is the provision of a relatively lightweight driven assembly incorporating the driven clutch element of the unit. This assembly includes the driven clutch element, a shaft to which it is secured and a motor pulley. These parts are so con structed as to introduce a minimum amount of inertia into the driven elements. Since the constantly driven flywheel is rotated at a speed in excess of 5,000 R. P. M. the ratio of the diameter of the motor pulley to that of the machine pulley may be relatively small in order to drive the machine at say 6,500 R. P. M. This makes possible a reduction in the inertia effect of the motor pulley. Moreover, the lightening of the intermittently driven parts of the unit reduces the momentum of these parts and thus brings about more rapid deceleration of the machine when the clutch is disengaged and the brake is applied to the driven clutch plate.

Another feature of the invention is the provision of noiseless speed increasing gearing between the motor shaft and the flywheel shaft, this gearing being enclosed within a lubricant retaining housing and being abundantly lubricated. Noiseless and eflicient operation of the unit is thus insured.

In a preferred embodiment of the invention the flywheel is coaxial with the motor shaft and its hub surrounds the motor shaft and is mounted thereon by means of antifriction bearings. If the flywheel is driven at 1.5 times the angular speed of the motor shaft the flywheel hub rotates about the shaft at an angular speed in relation to the latter of only half the speed of the shaft.

The flywheel may, however, be mounted on a shaft which is not coaxial with the motor shaft but is displaced to one side thereof. This enables the use of a simpler gear connection between the two shafts to bring about the'desired step-up in angular speed of the flywheel. It also reduces the overall length of the unit. However, it increases the overall height or width of the unit somewhat.

Other objects, features and advantages of the invention will appear from the detailed description of several illustrative embodiments of the same which will now be given in conjunction with the accompanying drawings, in which:

Fig. l is a view, largely in longitudinal vertical section but partly in front elevation, showing a preferred embodiment of the new power unit;

Fig. 2 is a front elevational view of a portion of the unit;

Fig. 3 is a vertical sectional view through the unit taken along the line 33 of Fig. 1, certain parts being broken away; and

Fig. 4 is a View similar to Fig. 1 showing a modified form of power unit embodying certain important features of theinvention. 1 l

For purposes of illustration the invention has been 3 shown as applied to a power unit of the general character disclosed, in the patent to Peets et a1. 2,004,055, granted June 4, 1935. Reference may be had to said patent for certain details not fully shown herein.

vReferring new to Figs. 1, 2, and 3, the new unit comprisesa main frame 14). having a plurality of feet 11 at its upper end. by which the frame may be attached to. the under face of a table top 12 by means of bolts. 13. It will be understood that the top 12 forms a part of a sewing machine table or other support on. which the machine to be, driven is mounted. Frame has a central, substantially enclosed housing portion 14 from which extends, toward the left (Fig. 1), an annular flange 15 forming an end bonnet for an electric motor. A bonnet 16 forms the opposite end of the housing of the motor, and spaced, flanges on the two bonnets are encircled by a cylindrical sheet metal band, 17 which completes. the enclosure for the-motor. Tie rods 16a extending from one bonnet to the other serve to retain the motor housing in assembled'relation. Within the motor housing is a shaft 18 which is journalled adjacent its left end (Fig. 1) in a bushing 19 carried by inwardly extending portions 20 of a housing 21 integral with the bonnet 16. At the opposite end of the motor housing the shaft 18 carries a sleeve 22 and beyond this is journalled in a bearing portion 23 provided centrally of a partition wall 24 within the portion 14 of the frame. A ball bearing unit 25 mounted in the frame portion 23 provides an anti-friction bearing for the shaft 18. A spring ring 26 serves to retain the bearing unit in place.

Within the motor housing is a field core 27 having incorporated in it an exciting winding 28. Suitable leads 29 extend from the latter into a connection housing 30, secured to the bonnet 16, by means of which power is supplied to the motor. On the shaft 13 there is mounted a rotor 31, which may be of the conventional squirrel cage induction type. The motor may, for example, be a three-phase, 60 cycle two pole motor adapted to operate at a rated speed of 3,450 R. P. M.

Keyed to. the shaft 18, just beyond the partition wall 24 of the frame, is a metal gear 32 which meshes with a laminatedplastic gear 33 carried by the hub of a metal gear 34. A screw threaded retaining ring 35 serves to hold the gear 33 on the hub of gear 34. The latter is suitably journalled on a stud 36, carried by the partition wall 24, which extends into the enclosed housing at the right of said wall (Fig. 1).

Roller bearing units 37 and 38, mounted on the opposite ends of the gear 34 and its hub, provide an antifriction bearing between the gear and the stud 36. A

threaded collar or nut 39, mounted on a screw threaded portion of the stud 36, serves to retain the assembly comprising the gear 34 and the roller bearing units on the journal portion of the stud 36. A lock washer 40 is provided between the nut 39 and the outer face of the roller bearing unit 38.

Gear 34 meshes with a laminated plastic gear 41 secured to a hub '42 of a flywheel 43. A screw threaded retainer or clamping ring 44 serves to hold the gear 41 against a shoulder of the hub 42. This hub and the flywheel are journalled on the shaft 18 by means of ball bearing units 45 and 46. A spacing sleeve 47 surrounding the shaft 18 serves to retain the inner members of the ball bearing units in propenly spaced relation, and the parts are held in assembled position by means of a nut 48 having screw threaded engagement with the right end of the shaft 18. By the employment of alternate metal and plastic gears in the gear train which serves to connect the motor shaft with the flywheel, the noise incident to the employment of all metal gears is greatly reduced. Moreover, this is achieved without the excessive wear of the gears which would result if all of the meshing gears were formed of laminated plastic material.

The gearing described is of such character that the flywheel is driven at a desired angular speed higher than 1 and gasket are held in position by screw 50a (Fig. 1).

4 l v that of the shaft 18. Preferably it is driven at a speed of about 1.5 times that of the. shaft. For this purpose the gears 32 and 33 may have a 1.3 to 1 peripheral speed ratio, while the gears 34 and 41 may have a 1.154 to 1 peripheral speed ratio. The gearing is enclosed within a lubricant retaining housing formed in part by the wall 24 and by a surrounding wall 49. The opposite face of the housing is closed by a plate 50 and a gasket 51. The plate To prevent discharge of lubricant from the housing, a sealing ring 52, formed of rubber or the like, is provided within a hub portion of. the plate 50 and is urged. into sealing relation with the wall of the housing and with the periphery of the hub 42 of the flywheel by means of a screw threaded clamping ring 53.= The escape of lubricant from the housing at the opposite side thereof is prevented by screw threaded formations 54 on the hub extension of Wall 24. This screw threaded formation is such as to drive toward the'interior of the housing any lubricant which tends to creep outwardly alongthe sleeve 22 carried by the shaft 18. Similarly, the escape of lubricant from the housing 21 of the bonnet 16 into the interior of the motor is prevented by frusto-conical oil slinger formations 55 onthe shaft 18.

Theflywheel 43 is preferably provided with a plurality of air propelling vanes 56 (Fig. l) on the face of the-flywheel facing toward the motor. These vanes serve to propel a cooling stream of air around the enclosed lubri-v cant housing and through openings 57 (Fig. 3) in the wall 24 of the frame. Overheating of. the motor and the driven parts is thus prevented. A sheet metal guard-'58, which may suitably be formed in two semi-circular sections to facilitate assembly, is supported in any suitable way from the frame 10 and surrounds the flywheel. I

Within a recess formed in the right face (Fig. 1) of the flywheel 43 is mounted a friction ring 59 formed of any suitable friction providing material. This is provided with a number of studs 59a cooperating with openings in the flywheel and is held in place by 'a snap ring 59b. Ring 59 cooperates with a clutch plate 69 having a, hub 61 secured to a shaft 62.. The latter is journalled in spaced roller bearing units 63 and 64 mounted in a sleeve 65 carried by a bearing portion 66 of the frame 10. To facilitate assembly of the parts, the bearing 66. is split along the plane of Fig. 1. At the outer or right end of the shaft 62 there is secured thereto a pulley 67 having a V-shaped groove in its periphery arranged to receive and drive a V-belt 68 which extendsupwardly through an opening in the table 12 to. a pulley on the sewing machine (not shown). The shaft 62, pulley 67, and other parts rotatable therewith are held in assembled relation by means of a pair of nuts 69 having screw threaded engagement with the outer end of the shaft 62. A spacing sleeve 70 surrounding the shaft serves to hold the bearing unit 63 and 64 in properly spaced relation.

Secured to the inner end of the sleeve 65 is a collar 71 (Figs. 1 and 2) having a radially extending arm 72 which receives the upper end of a rod 73 that extends downwardly to a foot treadle or knee press or other suitable means operable at will by the operator for rocking the collar. 71 and sleeve 65 when desired. A spring 74 normally urges thearm 72 upwardly and retains the parts in the position indicated in Fig. 2. At this time the clutch plate 60 is spaced slightly from the friction ring 59 of the'flywheel so that the pulley assembly will not be driven. When the collar 71 is rocked in the manner explained, however, a spiral projection 75 on the sleeve 65 cooperating with a spiral groove 76 in the inner surface of a relieved central portion of the bearing 66 will cause the sleeve 65 and the parts carried thereby to be shifted toward the left (Fig. 1). This brings about engagement of the clutch plate 60 with friction ring 59 and the driving of the pulley assembly at the speed of rotation of the flywheel 43. Upon release of the foot treadle connected with the rod 73 the spring 74 will restore the parts to the position indicated in Figs.

. l and 2, at which time the clutch is disengaged and the clutch plate 60 is brought into engagement with a brake shoe 77 to bring the shaft 62 quickly to rest. To minimize the inertia of the parts and thus insure quick stopping of the shaft 62, the clutch plate 60, pulley 67, and other rotating parts of the assembly are preferably made as light as possible consistent with the work these parts must perform. Brake shoe 77 is swivelly mounted on the reduced outer end of a screw threaded stud 78 cooperating with a screw threaded opening in a portion 79 of the frame. The screw stud is held in adjusted position by means of a lock nut 8%. To hold the brake element 77 against turning on the stud 7 8, it is provided with a downwardly extending arm 81 the lower end of which has spaced surfaces cooperating with the upper surface of a portion 82 of the frame. As shown, the brake shoe carries a friction lining 77a which cooperates with the adjacent face of the plate 60 to efiect the braking action.

A pulley guard 83 is preferably provided around the major portion of the pulley 67. This guard is secured by a pair of screws 83a (Fig. 2) to the lower end of a pivoted U-shaped bracket 84. The latter is pivoted at 85 on the frame and is normally urged into the position shown in Fig. 2 by a spring 86. When it is desired to have access to the pulley for replacement of the belt or the like, the guard may be swung downwardly with the bracket 84, about the pivot 85. To enable mounting of the power unit in a variety of diflerent angular positions in relation to the table, the guard 83 is provided with elongated slots 83b cooperating with the screws 33a, so that the circumferential position of the guard in relation to the bracket 84 may be adjusted to avoid interference with the belt 68.

It is believed that the construction and operation of the unit will be clear from the foregoing description. Assuming that the motor is of the character indicated, having a rated speed of 3,450 R. P. M., the flywheel 43 will be constantly rotated at a higher angular velocity, e. g. 5,175 R. P. M., if the gear ratios mentioned above are employed. It will be understood that when the sewing machine is in use, the motor and the flywheel will be constantly driven. The operator of the sewing machine, through the use of the foot treadle connected with the rod 73, controls the operation of the clutch to cause the sewing machine to be started and stopped at frequent intervals in the course of seaming garments and the like. The high angular speed of the flywheel and the low inertia of the parts driven when the clutch is engaged serves to insure rapid acceleration of the machine to its maximum desired speed. So also, the low inertia of the driven parts insures rapid deceleration and stopping of the machine when the clutch plate 69 is disengaged from the friction ring 59 and engaged with the brake element 77.

Turning now to Fig. 4, there is illustrated a modified form of the new power unit. This comprises a main frame 9% having feet 91 secured by means of bolts 92 to the under face of a sewing machine table top or other support 93. An electric motor94 is carried by the frame 90 in the manner described in relation to Fig. 1. Motor 94, however, has a shorter shaft 95 which terminates slightly beyond the bearing retaining portion of the right end bonnet which is integral with the frame 90. Adjacent the outer end of the shaft 95 there is keyed thereto a metal gear 96 which meshes with a laminated plastic gear 97 secured to a shaft 98. The latter is journalled in ball bearing units 99 and 100 mounted in spaced relation in a housing portion 101 of the frame 90. At its outer or right end, which projects through said housing portion of the frame, the shaft 98 carries a flywheel 102 similar to flywheel .3 of Fig. l. A friction ring 103 is suitably secured to the right face of the flywheel 102 and is arranged to cooperate with a clutch plate 104 whenever the latter is shifted toward the left. This clutch plate is secured to a shaft 105 coaxial with shaft 98 and journalled in ball bearing units 106 and 107 mounted in a sleeve 108 carried by a bearing portion of the frame 90. A collar 109, sim- V 6 V ilar to collar 71 of Fig. 2, is secured to the sleeve 108 and is arranged to cause rocking of the sleeve under control of a foot treadle or the like to bring about a slight axial shifting of the sleeve 108 to engage the clutch plate 104 with friction ring 103. At the outer end of shaft 105, socured for rotation therewith is a pulley 110 having a Y- groove adapted to receive a V-belt 111 which connects the pulley 110 with a pulley (not shown) on the main operat ing shaft of a sewing machine mounted on the .table 93. When the clutch assembly is in the position indicated in Fig. 4, a surface on the right face of the clutch plate 104 is engaged with a brake element 112 swivelly mounted on a screw threaded stud 113 which is adjustable in the manner explained in relation to stud 78 of Fig. 1. I

The primary difierence between the embodiment of Fig. 4 and that of Figs. 1 to 3, inclusive, is the offset relationship between the motor shaft and the flywheel supporting shaft 98. This enables the use of a single pair of gearsfor driving the flywheel from the motor shaft at an angular speed higher than that of the motor shaft. The gears 96 and 97 must be suitably selected to provide the desired step-up of speed. As shown, the gears may suitably be mounted in a lubricant retaining portion of the frame, and the flywheel may be provided with air impelling means to assist in cooling the motor and other parts of the unit. A belt guard 114, similar to guard 83, may be provided around the major portion of pulley 110.

in lieu of gearing 96 and 97 to connect the shafts 95 and 93, the latter may be interconnected by a belt and pulley arrangement, if desired. The belt and pulleys should be of a character insuring a positive drive between the shafts and may for this purpose be similar to that disclosed in the patent to Rubel, No. 2,628,583, granted February 17, 1953. It will be understood that the pulley mounted on the shaft 95 will be of larger diameter than that mounted on the shaft 98.

In lieu of the fixed mounting of the entire frame 10 or 917 in relation to the table top, as shown in the drawings, provision may be made for angular adjustment of the motor and clutch carrying portions of the frame and a support member secured to the table top. This will facilitate tightening of the belt which connects the motor driven pulley with the pulley on the sewing machine. Suitable arrangements for this purpose are disclosed in the patents to Le Vesconte et al., No. 2,390,220, granted December 4, 1945, and Peterson, No. 2,481,867, granted September 13, 194

While several illustrative embodiments of the invention have been disclosed in considerable detail and various modifications have been suggested, it will be understood that other changes may be made in the construction and arrangement of various parts of the unit within the scope of the invention. Certain features described in relation to one embodiment may be incorporated in the other.

What is claimed is:

l. A power drive for a sewing machine which comprises a frame, an electric motor having a shaft journalled in said frame, a flywheel journalled in said frame, connections from said motor shaft for rotating said flywheel, said connections including speed increasing means for driving said flywheel at greater angular speed than'said motor shaft, a driven shaft carried by said frame, means including a clutch connecting said flywheel with said driven shaft and a pulley carried by said driven shaft adapted for belt connection with a sewing machine.

2. A power drive for a sewing machine which comprises a frame, an electric motor having a shaft journalled in said frame, a flywheel journalled in said frame, connections from said motor shaft for rotating said flywheel, said connections including speed increasing means for driving said flywheel at greater angular speed than said motor shaft, a driven shaft carried by said frame, means including a clutch connecting said flywheel with said driven shaft, means operable at will for controlling the engagement and disengagement of said clutch, and a pulley carried by said. driven shaft adapted for belt connection with a sewing machine.

3. A, power drive for a sewing machine which comprises a frame, an electric motor carried by said frame, said motor having a power transmitting shaft, a flywheel rotatably mounted on said frame, connections from said shaft to said flywheel for driving the latter at greater angular speed than said shaft, a driven shaft carried by said frame, means including a clutch connecting said flywheel, with said driven shaft, means controlled by the operator for causing engagrnent and disengagement of said. clutch, and a pulley carried by said driven shaft adapted for belt connection with a sewing machine.

4. A power drive for a sewing machine which comprises a frame, an electric motor carried by said frame, Said motor having a power transmitting shaft, a flywheel rotatably mounted on said frame, gearing connecting said shaft to said flywheel for driving the latter at greater angular speed than said shaft, a driven shaft carried by said frame, means including a clutch connecting said flywheel With said driven shaft, means controlled by the operator for causing engagement and disengagement of said clutch, and a pulley carried bysaid driven shaft adapted forbelt connection with a sewing machine.

5. A power drive for a sewing machine which cornprises a frame, an electric motor carried by said frame, said motor having a power transmitting shaft, a flywheel rotatably mounted on said frame, gearing connecting said shaft to said flywheel for driving the latter at greater angular speed than said shaft, said gearing comprising a metal gear and a laminated plastic gear, a driven shaft carried by said frame, means including a clutch connecting said flywheel with said driven shaft, means controlled by the operator for causing engagement and disengagement of said clutch, and a pulley carried by said driven shaft adapted for belt connection with a sewing machine.

6. A power drive for a sewing machine which comprises a frame, an electric motor carried by said frame, said motor having a power transmitting shaft,-a flywheel rotatably mounted on said frame, gearing connecting said shaftto said flywheel for driving the latter at greater angular speed than said shaft, a lubricant retaining housing on said frame enclosing said gearing, a driven shaft carried by said frame, means including a clutch connecting said flywheel with said driven shaft, means controlled by the operator for causing engagement and disengagement of said clutch, and a pulley carried by said driven shaft adapted for belt connection with a sewing machine.

7. A power drive for a sewing machine which cornprises a frame, an electric motor carried by said frame, said motor having a power transmitting. shaft, 21 flywheel rotatably mounted on said frame, in coaxial alinement with said shaft, gearing connecting said shaft to said flywheelfor driving the latter at greater angular speed than said shaft, a driven shaft carried by said'frame, means including a clutch connecting said flywheel with said driven shaft, means controlled by the operator for causing engagement and disengagement of said clutch, and a pulley carried by said driven shaft adapted for belt connection with a sewing machine.

8. A power drive for a sewing machine which comprises a frame, an electric motor carried by said frame, said motor having a power transmitting shaft, a flywheel rotatably mounted on said shaft for rotation in relation thereto, gearing connecting saidshaft to said flywheel for drivingthe latter at greater angular speed than said shaft, a driven shaft carried by said frame, means including a clutch connecting said flywheel with said driven shaft, means controlled by the operator for causing engagement and disengagement of said clutch, and a pulley carried by said driven shaft adapted' for belt connection with a sewing machine.

9. A power drive for a sewing machine which comprises a frame, an electric motor carried by said frame, said motor having a power transmitting shaft, a flywheel rotatably mounted on said frame, connections from said shaft to said flywheel for driving the latter at greater angular speed than said shaft, a driven shaft carried by said frame, in axial alinement with the axis of said flywheel, a clutch plate secured to said shaft adjacent said flywheel, means operable by the operator for shifting said driven shaft axially'to carry said clutch plate into frictional engagement with said flywheel for operation of said driven shaft by the motor, a brake for arresting rotation of said driven shaft upon release of said shaft shifting means, and a pulley secured to said driven shaft adapted for belt connection with a sewing machine.

10. A power drive for a sewing machine which comprises a frame, an electric motor having a driving shaft, a flywheel and a driven clutch member mounted on said frame in coaxial alinernent with each other, gearing connecting said flywheel with said motor shaft for rotation of said flywheel at greater angular speed than'said motor shaft, means for shifting said clutch, member into frictional engagement with said flywheel for direct driving connection therebetween, and a pulley rigidly connected with said clutch member for rotation thereby, said pulley being adapted for belt connection with a sewing machine.

11. A pov er drive for a sewing machine which comprises a frame, an electric motor having a driving shaft, a flywheel and a driven clutch member mounted on said frame in coaxial alinement with each other, said flywheel having a hub mounted on said motor shaft and rotatable in relation thereto, gearing connecting said flywheel with said motor shaft for rotation of said flywheel at greater angular speed than said motor shaft, means for shifting said clutch member into frictional engagement with said flywheel for direct driving connection therebetween, and a pulley rigidly connected with said clutch member for rotation thereby, said pulley being adapted for belt connection with a sewing machine.

12. A power drive for a sewing machine which com prises a frame, an electric motor having a driving shaft, a flywheel and a driven clutch member mounted on said frame in coaxial alinement with each other, gearing connecting said flywheel with said motor shaft for rotation of said flywheel at greater angular speed than said motor shaft, means for shifting said clutch member into frictional engagement with said flywheel for direct driving connection therebetween, spring means for disengaging said clutch member from said flywheel upon release of said shifting means, a brake for arresting rotation of said clutch member when so disengaged, and a pulley rigidly connected with said clutch member for rotation thereby, said pulley being adapted for belt connection with a sewing machine.

References Cited in the file of this patent UNITED STATES PATENTS

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