US316065A - Oscillating looper for sewing-machines - Google Patents

Description

(Model.)

T. G. ROBINSON.

OSGILLATING- LOOPER FOR SEWING MACHINES. No. 316,065.

Patented Apr. 21, 1885.

NrTEn STATES PATENT EETCE.

THOMAS C. ROBINSON, OF BOSTON, ASSICrNOB OF ONE-HALF TO E. B. WELCH, OF CAMBRIDGE, MASSACHUSETTS.

OSClLl .AT|NG LOOPER FOR SEWING-MACHINES.

SPECIFICATION forming part of Letters Patent No. 316,065, dated April 21, 1885.

Application led March 27, 1884. (Model.) v

To all whom it may concern:

Be itknown that I, THOMAS O. ROBINSON, of Boston, in the county of Suffolk and State of Massachusetts, have invented certain Improvements in Oscillating Loopers or Hooks for Sewing-Machines, of which the following isa specification.

The invention has for its object to provide certain improvements in the form of the hook of a chain -stitch sewing-machine, whereby said hook when opening the loop for the suceeeding stitch is prevented from pulling said loop or increasing the tension of the thread.

Of the accompanying drawings, forming a part of this specification, Figure l represents a side elevation of part of a sewing-machine having my improvements. Fig. 2 represents an end view ofthe same. Figs. 3 and 4 represent perspective views of the improved hook, showing it in different positions. Figs. 4fL and 4b represent modifications. Fig. 5 represents an end view of a hook of old form.

The same letters of reference indicate the same parts in all the figures. a represents the hook of a chain-stitch sewing-machine, said hook operating in the usual manner in catching the needle -thread and opening it while the succeeding stitch is made through the loop thus afforded. The hook, as usual, has two prongs, 2 3,' connected by a neck, 4, with the shank 7, which is secured to the oscillating arbor d', whereby the hook is operated as usual.

Heretofore the side of the neck 4 on which the loop slips while it is being thus openedviz., the side nearest the prong 2-has been so formed that it will exert a constant strain or pull on the thread while opening the loop, thiseffect being due to the fact that the side of the neck 4 on which the thread bears and slips during the loop-opening movement as heretofore formed is receding during said movement from the material with which the loop is engaged, and therefore constantly tightens the loop, as shown in Fig. 5. rlhe result is that the tension of the thread is widely varied, being at times slack and at other times excessively tight 5 hence imperfect stitching is produced, and breakage of thread is 5o liable to occur. In making my improved a' ofthe hook proper in a single curve con- 6o l tinuous from the point 2 to the end of the hook at 4, so that as the hook moves to open the loop the distance between the point in the work from which the loop-passes, and any part of the side of the neck along which it slips while being opened will not be greater to any considerable extent than the original length of the loop when the prong 2 first enters it. This form enables the loop to remain in a substantially loose condition while 7o it is being opened. It will be seen that the form of the side of the neck to produce this result, or an approximation thereto, may be considerably modified. I prefer the form shown in Figs. 2, 3, and 4, in which the loop- 75 opening side of the neck has a gradual curve or recess, 6, extending from the point of the prong 2 to a point at the opposite side of the center of rotation (via, the center ofthe shank 7) from said prong. Whenthehookis at'the ex- 8o treme of its loop-opening movement, as shown in Fig. 2, the loop is contained in the inner part rof the recess 6. Vhile this form is the best of any I have devised, I do not limit myself to the depth of the recess 6 shown, nor to the exten- 8 5 sion of the said recess beyond the center of the shank. Figs. 4fL and 4b show the recess 6 made of lesser depth than in the iigures above described, the recess being carried about to the center of the shank but not beyond in 9o a continuous curve. The hook thus improved moves from one position to the other without causing strain on the loops by either of its movements, the hook slipping easily through the loops but not tightening them.'

It will be understood that the leading prong ofthe hook is oiiset from the plane of the body, as usual in looper-hooks, and shown clearly in Fig. l.

I claim-- IOO lia

The improved doublepointed looper or osl to this specification, in the lpresence of two oillating hook for chain-stitch sewing-masubscribing Witnesses, this 21st day of March, 1o ehines, having one point deflected from the 1884. plane of the other and having its side a formed T 5 in a. single continuous curve from the point 2 THOMAS C ROBE' SON to the recess which terminates the hook prop- Witnesses: er, substantially as shown and described. .0. F. BROWN, In testimony whereof I have signed myname A. L. WHITE.

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