GB2068027A - Top spring for sewing machine foot bar - Google Patents

Abstract

An attachment for mounting on a sewing machine comprising a platform 2 mounted on a member, a, of the machine, a leaf spring 4, being mounted at one end on the platform and at the other end engaging a nylon plunger, 6b, passing through a bush, 6, in the platform to engage the upper end of a foot-bar, 1, to apply pressure to the foot, 1b. A second bracket 7 is mounted on the platform with a stud passing through a transverse member of the second bracket to apply tension to the leaf spring, 4, in order to vary the pressure on the foot for high speeds of 2,500-3,000 r.p.m. <IMAGE>

Description

SPECIFICATION R.S.M. top spring for sewing machines This invention relates to an attachment mounted on a sewing machine for adjusting the tension applied to the foot which feeds the material through the machine. It has been proposed to employ a spring in the foot bar but such a construction is unable to cope with speeds of 2,500-3,000 stitches per minute and the stitch decreases in size.

An adjustable foot-bar for a sewing machine comprising a leaf spring mounted at one end on a bracket carried by the machine and at the other end engaging a plunger extending through a bush applying pressure to a presser foot of the machine, means being provided for adjusting the pressure on the plunger to vary the pressure on the presser foot.

The invention will be described with reference to the accompanying drawings:- Fig. 1 is a side elevation of a sewing machine, Fig. 2 is a side elevation to a larger scale of the leaf spring mounting; Fig. 3 is a plan of Fig. 2; Fig. 4 is a detail view at right angles to Fig. 2, of the spring adjustment.

The upper end of a foot- bar 1 engages a nylon plunger 6b passing through a bush 6 affixed to a platform 2 carrying a bracket 3 extending above and parallel to the horizontal member a of the sewing machine. Above the platform 2 is mounted a leaf spring 4 extending substantially parallel therewith and having one end affixed to the bracket 3 by a pin 3a and at the other end engaging the head 6a of the plunger 6b extending through the screwed bush 6 affixed to the platform 2. The platform 2 is carried on pillars 5 from the member a.

A second bracket or bridge 7 is mounted on the platform 2 through which the spring 4 passes and is adjusted by a screwed stud 10. The bracket 7 is formed with a transverse member 8 extending between the two legs 9 of the second bracket 7.

The transverse member 8 is formed with a screwed hub 8a through which passes the screwed stud 10 having a knurled head 11 , the free end of the stud engaging the upper side of the leaf spring 4 to vary the tension applied to the leaf spring to adjust the tension on the foot-bar.

A knurled lock nut 12 is provided to lock the stud 10 in the required position.

In use the pressure on the leaf spring 4 is adjusted so that the presser foot 1 b on the lower end of the footbar 1 applies the desired pressure of the foot on the material being sewn as it passes under the foot.

With the machine operating at high speeds of 2,500-3,000 r.p.m. the pressure on the foot 1 b is adjusted so as the material is fed under the foot, a pressure is given thereto to produce a predetermined feed for the production of the predetermined length of stitch.

The platform 2 is mounted over the threaded portion of the bush 6, a nut holds the platform parallel, to the sewing machine A two pillars 8 are screwed to the sewing machine to maintain a solid platform.

1. An adjustable foot-bar for a sewing machine comprising a leaf spring mounted at one end on a bracket carried by the machine and at the other end engaging a plunger extending through a bush applying pressure to a presser foot of the machine, means being provided for adjusting the pressure on the plunger to vary the pressure on the presser foot.

2. An adjustable foot-bar as in claim 1, in which the pressure on the leaf spring is controlled by a screwed stud engaging the upper surface of the leaf spring.

3. An adjustable foot-bar for a sewing machine substantially as described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION R.S.M. top spring for sewing machines This invention relates to an attachment mounted on a sewing machine for adjusting the tension applied to the foot which feeds the material through the machine. It has been proposed to employ a spring in the foot bar but such a construction is unable to cope with speeds of 2,500-3,000 stitches per minute and the stitch decreases in size. An adjustable foot-bar for a sewing machine comprising a leaf spring mounted at one end on a bracket carried by the machine and at the other end engaging a plunger extending through a bush applying pressure to a presser foot of the machine, means being provided for adjusting the pressure on the plunger to vary the pressure on the presser foot. The invention will be described with reference to the accompanying drawings:- Fig. 1 is a side elevation of a sewing machine, Fig. 2 is a side elevation to a larger scale of the leaf spring mounting; Fig. 3 is a plan of Fig. 2; Fig. 4 is a detail view at right angles to Fig. 2, of the spring adjustment. The upper end of a foot- bar 1 engages a nylon plunger 6b passing through a bush 6 affixed to a platform 2 carrying a bracket 3 extending above and parallel to the horizontal member a of the sewing machine. Above the platform 2 is mounted a leaf spring 4 extending substantially parallel therewith and having one end affixed to the bracket 3 by a pin 3a and at the other end engaging the head 6a of the plunger 6b extending through the screwed bush 6 affixed to the platform 2. The platform 2 is carried on pillars 5 from the member a. A second bracket or bridge 7 is mounted on the platform 2 through which the spring 4 passes and is adjusted by a screwed stud 10. The bracket 7 is formed with a transverse member 8 extending between the two legs 9 of the second bracket 7. The transverse member 8 is formed with a screwed hub 8a through which passes the screwed stud 10 having a knurled head 11 , the free end of the stud engaging the upper side of the leaf spring 4 to vary the tension applied to the leaf spring to adjust the tension on the foot-bar. A knurled lock nut 12 is provided to lock the stud 10 in the required position. In use the pressure on the leaf spring 4 is adjusted so that the presser foot 1 b on the lower end of the footbar 1 applies the desired pressure of the foot on the material being sewn as it passes under the foot. With the machine operating at high speeds of 2,500-3,000 r.p.m. the pressure on the foot 1 b is adjusted so as the material is fed under the foot, a pressure is given thereto to produce a predetermined feed for the production of the predetermined length of stitch. The platform 2 is mounted over the threaded portion of the bush 6, a nut holds the platform parallel, to the sewing machine A two pillars 8 are screwed to the sewing machine to maintain a solid platform. CLAIMS

1. An adjustable foot-bar for a sewing machine comprising a leaf spring mounted at one end on a bracket carried by the machine and at the other end engaging a plunger extending through a bush applying pressure to a presser foot of the machine, means being provided for adjusting the pressure on the plunger to vary the pressure on the presser foot.

2. An adjustable foot-bar as in claim 1, in which the pressure on the leaf spring is controlled by a screwed stud engaging the upper surface of the leaf spring.

3. An adjustable foot-bar for a sewing machine substantially as described with reference to the accompanying drawings.