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TRIFLAT PULLEY

IP.com Disclosure Number: IPCOM000026711D
Original Publication Date: 1993-Apr-30
Included in the Prior Art Database: 2004-Apr-06
Document File: 2 page(s) / 86K

Publishing Venue

Xerox Disclosure Journal

Abstract

It is common practice to secure pulleys and sprockets to a shaft using a setscrew. In order to transmit all but very small torques, features in addition to the setscrew must be incorporated into the assembly. A common method for doing this is to utilize a flat on the shaft and a properly sized "D" shaped hole in the mating part. This design has proven unreliable in many applications. The instant disclosure recognizes that relative motion between pulley and shaft results in the removal of material through fretting and abrasion. The problem simply stated, is that commonly employed method of securing the pulley to the shaft leaves freedom of rotation of the pulley about the setscrew. A moment is created about the setscrew when a load does not act directly through it, but rather at some distance from it. This moment will quickly wear the areas between the setscrew and the shaft and the mating flats between the parts, as previously described.

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XEROX DISCLOSURE JOURNAL

TRIFLAT PULLEY Classification Proposed Norman L. Roof, Sr. US. C1.403/87

Int. C1. F16c 11/00

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XEROX DISCLOSURE JOURNAL - Vol. 18, No. 2 MarcWAprill993 227

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TRIFLAT PULLEY (Cont'd)

It is common practice to secure pulleys and sprockets to a shaft using a setscrew. In order to transmit all but very small torques, features in addition to the setscrew must be incorporated into the assembly. A common method for doing this is to utilize a flat on the shaft and a properly sized "D" shaped hole in the mating part. This design has proven unreliable in many applications. The instant disclosure recognizes that relative motion between pulley and shaft results in the removal of material through fretting and abrasion. The problem simply stated, is that commonly employed method of securing the pulley to the shaft leaves freedom of rotation of the pulley about the setscrew. A moment is created about the setscrew when a load does not act directly through it, but rather at some distance from it. This moment will quickly wear the areas between the setscrew and the shaft and the mating flats between the parts, as previously described.

The triflat design illustrated in the figure overcomes the aforedescribed problems. The basic premise of the triflat design is that instead of using a single flat on drive shaft 10 to transmit the torque, two flats, 12, are used which are nearly orthogonal...