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Stress-Reducing Tractor Pulley

IP.com Disclosure Number: IPCOM000120454D
Original Publication Date: 1991-Apr-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 69K

Publishing Venue

IBM

Related People

Lee, HC: AUTHOR [+4]

Abstract

The stresses in a flat belt riding on a pulley can be reduced if the pulley is crowned. A manufacturing method is disclosed that reduces stresses by producing a crowned pulley and compensating for molding imperfections.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 64% of the total text.

Stress-Reducing Tractor Pulley

      The stresses in a flat belt riding on a pulley can be reduced
if the pulley is crowned.  A manufacturing method is disclosed that
reduces stresses by producing a crowned pulley and compensating for
molding imperfections.

      Fig. 1 is a cross section of the periphery of molded pulley 1
around which thin steel belt 2 is wrapped.  Belt 2 is significantly
wider than pulley 1.  The arrow indicates the direction of flow of
thermoplastic into the mold.  The molding process produces two
undesirable effects:  the pulley contour is tapered, as indicated by
the angle r, and the periphery is concave between its edges.  As a
result of these molding effects, the belt is not flat, but has
deformations in the form of ridges at 3 and 4 which constitute
regions of high stress because the tops of these ridges are located
farthest from the neutral axis of this belt which is wrapped around
pulley 1 in the other plane.

      Two factors cause these ridges in belt 2: anticlastic bending,
and lack of support in the center of the pulley. If the pulley
periphery was flat and the belt was perfectly aligned with the pulley
surface, the deformations in the belt would be minimized.  Perfect
alignment is rarely attained; however, a crowned pulley surface will
significantly reduce the stresses from the condition shown in Fig. 1
even if the belt is misaligned with respect to the pulley.

      Fig. 2 shows how mold 5 is modified to produce th...