Browse Prior Art Database

Index Pawl Redesign for Improved Overthrow Stopping

IP.com Disclosure Number: IPCOM000051410D
Original Publication Date: 1981-Jan-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Brown, CG: AUTHOR

Abstract

Fig. 1 illustrates a prior art ratchet arrangement in configuration for indexing a platen. The engagement of the index pawl 10 and the ratchet 12 is a compromise between the need for the drive of the pawl 10 against ratchet 12 and the desire to prevent overthrow of the ratchet due to the inertia and subsequent camming of the index pawl from the teeth of the ratchet 12. Overthrow stop 14 tends to restrict the driving of the index pawl out of engagement with the teeth of ratchet 12, but is not totally reliable due to its inability to obtain adequate stiffness or resistance to deformation. The inertia of the platen and platen ratchet tend to deform the overthrow stop and cam the index pawl out of engagement.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 83% of the total text.

Page 1 of 2

Index Pawl Redesign for Improved Overthrow Stopping

Fig. 1 illustrates a prior art ratchet arrangement in configuration for indexing a platen. The engagement of the index pawl 10 and the ratchet 12 is a compromise between the need for the drive of the pawl 10 against ratchet 12 and the desire to prevent overthrow of the ratchet due to the inertia and subsequent camming of the index pawl from the teeth of the ratchet 12. Overthrow stop 14 tends to restrict the driving of the index pawl out of engagement with the teeth of ratchet 12, but is not totally reliable due to its inability to obtain adequate stiffness or resistance to deformation. The inertia of the platen and platen ratchet tend to deform the overthrow stop and cam the index pawl out of engagement.

The redesign of the index pawl is illustrated in Figs. 2 and 3.

It includes a plurality of teeth formed to mate with the teeth 18 on ratchet 12, which improves the control and alters the dynamics of the system to reduce the tendency for the index pawl to be cammed out of engagement with the ratchet teeth. As additional teeth of the index pawl 16 engage the teeth 18 of ratchet 12, the effective camming point moves away from the overthrow stop 14 back toward the pivot point 20 of index pawl 16. Thus, the overthrow stop provides a force engaging the pin of the index pawl, and the force exerted on the index pawl teeth by the teeth 18 of ratchet 12 must be multiplied to something in the order of twice the force exer...