Browse Prior Art Database

Constant Download Friction Drive Disclosure Number: IPCOM000099172D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 2 page(s) / 48K

Publishing Venue


Related People

Beck, VD: AUTHOR [+1]


A method to cancel the variation in download by the end of a drivebar is disclosed.

This text was extracted from an ASCII text file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 99% of the total text.


Download Friction Drive

       A method to cancel the variation in download by the end of
a drivebar is disclosed.

      Friction drive units are frequently used in mechanical for high
precision positioning.  They suffer from disadvantage that the
download exerted on the driven varies with the extension of the

      Fig. 1 shows an example of such a drivebar system.  If a 1 of
length L and weight W is extended a distance B where it is supported
by the friction drive unit 2, will exert a force of W(B- L/2)/B on
the driven object 3. has been assumed that the center of gravity of
the is at L/2, but this is not necessary.  The of the download force
causes a variation in the or distortion of the driven object.  If the
object is off-center, a varying pitching moment is also applied the
load.  It should be noted that a download force at end of the
drivebar is not necessarily a disadvantage it can be used as a
preload.  It is the variation in download with extension of the
drivebar which is the

      Fig. 2 shows a preload roller 4 which has been added to
drivebar system.  The preload roller exerts a force P on drivebar at
a distance C from the drive point and exerts force PC/B on the driven
object.  If the product PC equals the download force at the end of
the drivebar does not as the drivebar extends and retracts.  The
product PC a torque exerted about the drive point.  Means other than
preload roller can be used to create this tor...