Browse Prior Art Database

Linear Actuator With Asymmetric Bearing Angles

IP.com Disclosure Number: IPCOM000120138D
Original Publication Date: 1991-Mar-01
Included in the Prior Art Database: 2005-Apr-02
Document File: 2 page(s) / 89K

Publishing Venue

IBM

Related People

Hatchett, MR: AUTHOR [+2]

Abstract

This article discloses an improved linear actuator of the type commonly used in magnetic disk files wherein the read/write heads are mounted on a carriage assembly which runs along two parallel guide rails by means of six bearings mounted on the carriage in pairs. In this so-called six bearing configuration, two of the pairs are mounted on one side of the carriage with one pair on the other side, the angle between the bearings of each pair being 90 degrees. It is common to load the carriage onto the rails by means of a preload applied to one of the bearings. A consequence of employing this type of configuration is the imbalance in load which is created which can lead to excessive wear on some of the bearings and associated guide rails.

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Linear Actuator With Asymmetric Bearing Angles

      This article discloses an improved linear actuator of the
type commonly used in magnetic disk files wherein the read/write
heads are mounted on a carriage assembly which runs along two
parallel guide rails by means of six bearings mounted on the carriage
in pairs.  In this so-called six bearing configuration, two of the
pairs are mounted on one side of the carriage with one pair on the
other side, the angle between the bearings of each pair being 90
degrees. It is common to load the carriage onto the rails by means of
a preload applied to one of the bearings.  A consequence of employing
this type of configuration is the imbalance in load which is created
which can lead to excessive wear on some of the bearings and
associated guide rails.

      The improvement described in this article lies in the use of
different angles between the bearings making up each pair, the angle
values being chosen primarily to improve load balance between the
bearings but also to compensate for tilting of the carriage due to
differential thermal expansion effects.

      Figs. 1 and 2 show isometric front and rear views,
respectively, of the carriage assembly.  Fig. 3 is a schematic rear
view of part of the carriage assembly showing the bearing geometry.

      The bearings are rotatably mounted in canted pairs onto the
carriage assembly 2.  One pair of bearings 10 is positioned on one
side of a horizontal member 20 and the two remaining pairs 12,14 are
positioned symmetrically about the single pair such that the forward
pair 12 is located on one of the side walls of the vertical member
22.  The bearings 10, 12, 14 engage with two guide rails 30, 32 which
are located in grooves in the actuator structure 40.  The lower of
the bearings 10' of the single pair is biased towards the rail by
means of a spring (not shown), thus preloading the whole carriage
assem...