GB2026643A

GB2026643A - Pulley Guard

Info

Publication number: GB2026643A
Application number: GB7925938A
Authority: GB
Original assignee: HILL BV
Current assignee: HILL BV
Priority date: 1978-07-26
Filing date: 1979-07-25
Publication date: 1980-02-06
Also published as: GB2026643B

Abstract

A pulley guard having a pair of mutually engageable flanged plates 20, 21 which fit on opposite sides of a pulley wheel 16 and enclose the latter except for a gap between the flanges 20a, 21a, for passage of a belt (not shown), the plates 20, 21 being securable in relatively rotationally adjustable positions to vary the length of the gap according to the size of pulley wheel 16 being used. <IMAGE>

Description

SPECIFICATION Pulley Guard This invention relates to a pulley guard, i.e. a device for guarding against damage or injury by a rotating pulley wheel or a belt engaged with the wheel.

The invention is particularly useful with regard to sewing machine motors. Commercially, sewing machines are usually driven by a V-belt drive from an electric motor. The motor drives a pulley wheel and a gv-belt is engaged with the pulley wheel and with a further pulley wheel on the sewing machine. Round leather belts are sometimes used, but V-belts are much more common, because of their longer life and lower propensity to stretch. Whereas any belt can cause injury, it is particularly serious, for example, for a finger to be caught between a pulley and a V-belt, there being a high risk of severing of the finger tip. Many existing pulley guards leave a large gap into which it is easy for a finger to be accidentally inserted.

Interchangeable pulley wheels are usually provided for use with a particular motor. Some existing guards provide adequate protection when the largest diameter pulley is in use, but not when smaller diameter pulleys are used.

The present invention provides a very simple guard, which can be cheaply made and which is easily adjustable according to the pulley wheel being used, so that adequate protection is always provided.

The invention provides a pulley guard having a pair of mutualiy engageable flanged plates which fit on opposite sides of a pulley wheel and enclose the latter except for a gap between the flanges for passage of a belt, the plates being securable in relatively rotationally adjustable positions to vary the length of the gap according to the size of pulley wheel being used.

Reference is now made to the accompanying drawings, wherein:- Figure 1 is an exploded perspective view of the output end of a sewing machine motor showing a guard according to the invention and a pulley wheel associated with the motor; and Figure 2 is a diagrammatic view of the guard illustrating its adjustability.

The sewing machine motor 11 has an output shaft 1 2, which projects from a shallow boss 13.

The free end of the shaft 12 carries a screw thread 14. A pulley wheel 16 formed to take a Vbelt (not shown) has a hub (not shown) which fits on the shaft 12, the hub being keyed to the shaft.

A nut (not shown) is engaged with the thread 14 to hold the pulley wheel on the shaft.

The guard comprises an inner flanged plate 20 and an outer flanged plate 21. Each plate is discshaped with a part-cylindrical flange, 20a, 21 a respectively. The inner plate 20 has an aperture 22, which permits fitting of the inner plate over the boss 13. The plate has a pair of arcuate slots 24, 25 concentric with the aperture 22. The inner plate is secured to the body of the motor 11 by bolts (only one shown) 26 engaging through one of the slots 24 with screw-threaded apertures 27, 28 in the body. The purpose of the other slot 25 is described below.

The flange 21 a of the outer plate 21 has a pair of aligned longitudinal arcuate slots 30, 31 and the inner plate 20 has irregularly spaced screwthreaded apertures such as 33 to 35. The flange 21 a fits over the flange 20a, so as to define an enclosure for the pulley 16, with an arcuate gap defined between an end of the flange 20a and an end of the other flange 21 a. The flanges are secured together by bolts (only one shown in Figure 1) 36 engaging, one through each slot 30, 31 with a screw-threaded aperture such as 34.

The arcuate length of the gap is variable, by rotation of the outer plate 21 relative to the inner plate 20. The two flanges can be secured together in different rotational positions by selection of appropriate apertures in the flange 20a. The different possible gap sizes are illustrated in Figure 2, three sizes being shown, each corresponding to a respective pulley wheel. The size of the gap is pre-determined to give just sufficient clearance for a vibrating belt with the corresponding pulley fitted.

Sewing machine motors are provided with all of the parts illustrated except, the inner plate 20.

A small plate is provided for holding of the outer plate thereto and this is replaced by the inner plate 20, described, to adapt the guard according to the present invention. The small plate is not intended as a guard plate and is completely ineffective as such.

The additional slot 25 in the inner plate is intended for use with a similar but different motor whose securing positions are slightly different.

The inner plate can, therefore, be used with different motors to provide protection to the sewing machine operator.

Claims

1. A pulley guard having a pair of mutually engageable flanged plates which fit on opposite sides of a pulley wheel and enclose the latter except for a gap between the flanges for passage of a belt, the plates being securable in relatively rotationally adjustable positions to vary the length of the gap according to the size of pulley wheel being used.

2. A pulley guard according to Claim 1, wherein the flanges of the plates are in mutual sliding engagement, one within the other.

3. A pulley guard according to Claim 2 including at least one aperture in one of the flanges for receiving a headed fastener to fasten the flanges together, the other of the flanges having an elongate aperture extending circumferentially of the flange for receiving the headed fastener and permitting said angular adjustment between the flanged plates.

4. An electric motor having a rotatably driven shaft projecting from a body of the motor, a pulley for a belt mounted on the shaft for rotation therewith, and a pulley guard comprising a first plate having a part-cylindricai flange and secured

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Pulley Guard This invention relates to a pulley guard, i.e. a device for guarding against damage or injury by a rotating pulley wheel or a belt engaged with the wheel. The invention is particularly useful with regard to sewing machine motors. Commercially, sewing machines are usually driven by a V-belt drive from an electric motor. The motor drives a pulley wheel and a gv-belt is engaged with the pulley wheel and with a further pulley wheel on the sewing machine. Round leather belts are sometimes used, but V-belts are much more common, because of their longer life and lower propensity to stretch. Whereas any belt can cause injury, it is particularly serious, for example, for a finger to be caught between a pulley and a V-belt, there being a high risk of severing of the finger tip. Many existing pulley guards leave a large gap into which it is easy for a finger to be accidentally inserted. Interchangeable pulley wheels are usually provided for use with a particular motor. Some existing guards provide adequate protection when the largest diameter pulley is in use, but not when smaller diameter pulleys are used. The present invention provides a very simple guard, which can be cheaply made and which is easily adjustable according to the pulley wheel being used, so that adequate protection is always provided. The invention provides a pulley guard having a pair of mutualiy engageable flanged plates which fit on opposite sides of a pulley wheel and enclose the latter except for a gap between the flanges for passage of a belt, the plates being securable in relatively rotationally adjustable positions to vary the length of the gap according to the size of pulley wheel being used. Reference is now made to the accompanying drawings, wherein:- Figure 1 is an exploded perspective view of the output end of a sewing machine motor showing a guard according to the invention and a pulley wheel associated with the motor; and Figure 2 is a diagrammatic view of the guard illustrating its adjustability. The sewing machine motor 11 has an output shaft 1 2, which projects from a shallow boss 13. The free end of the shaft 12 carries a screw thread 14. A pulley wheel 16 formed to take a Vbelt (not shown) has a hub (not shown) which fits on the shaft 12, the hub being keyed to the shaft. A nut (not shown) is engaged with the thread 14 to hold the pulley wheel on the shaft. The guard comprises an inner flanged plate 20 and an outer flanged plate 21. Each plate is discshaped with a part-cylindrical flange, 20a, 21 a respectively. The inner plate 20 has an aperture 22, which permits fitting of the inner plate over the boss 13. The plate has a pair of arcuate slots 24, 25 concentric with the aperture 22. The inner plate is secured to the body of the motor 11 by bolts (only one shown) 26 engaging through one of the slots 24 with screw-threaded apertures 27, 28 in the body. The purpose of the other slot 25 is described below. The flange 21 a of the outer plate 21 has a pair of aligned longitudinal arcuate slots 30, 31 and the inner plate 20 has irregularly spaced screwthreaded apertures such as 33 to 35. The flange 21 a fits over the flange 20a, so as to define an enclosure for the pulley 16, with an arcuate gap defined between an end of the flange 20a and an end of the other flange 21 a. The flanges are secured together by bolts (only one shown in Figure 1) 36 engaging, one through each slot 30, 31 with a screw-threaded aperture such as 34. The arcuate length of the gap is variable, by rotation of the outer plate 21 relative to the inner plate 20. The two flanges can be secured together in different rotational positions by selection of appropriate apertures in the flange 20a. The different possible gap sizes are illustrated in Figure 2, three sizes being shown, each corresponding to a respective pulley wheel. The size of the gap is pre-determined to give just sufficient clearance for a vibrating belt with the corresponding pulley fitted. Sewing machine motors are provided with all of the parts illustrated except, the inner plate 20. A small plate is provided for holding of the outer plate thereto and this is replaced by the inner plate 20, described, to adapt the guard according to the present invention. The small plate is not intended as a guard plate and is completely ineffective as such. The additional slot 25 in the inner plate is intended for use with a similar but different motor whose securing positions are slightly different. The inner plate can, therefore, be used with different motors to provide protection to the sewing machine operator. Claims

4. An electric motor having a rotatably driven shaft projecting from a body of the motor, a pulley for a belt mounted on the shaft for rotation therewith, and a pulley guard comprising a first plate having a part-cylindricai flange and secured to the body between the pulley and the body, the flange being concentric with the shaft, and a second plate having a part-cylindrical flange which slidably engages the flange of the first plate, so as to enclose the pulley except for an arcuate gap defined between the ends of the two flanges for receiving a belt, the gap being variable in length by rotatably adjusting the second flange relative to the first flange, and means for securing the flanges together in a plurality of relatively angularly adjusted positions.

5. A. pulley guard for a sewing machine electric motor constructed substantially as herein described with reference to the accompanying drawings.