Post by thread:[OT:] Non circular gears

We (me anyway) are accustomed to thinking of gears as being circular. However, pairs of unlikely looking gears matched to each other can remain in mesh throughout a rotation cycle, just as circular gears do, but impart a wide range of useful relationships between the input and output parts. eg linear forward motion to a slider with quick return, stop and dwell motion etc This company provides a wide range of non-circular gears. Interesting examples provided. http://www.cunningham-ind.com/ ____________________ ref from Ken Mardle. SAMPLE Elliptical Gears: An ellipse is defined by a set of points in a plane, such that the sum of the distances from two fixed points - the foci - to any point in the set is a constant. This enables elliptical gears cut about their foci to run at a constant center distance. The velocity ratio resulting from elliptical gears varies between 1/K and K during one cycle of speed change, where K is the maximum gear ratio. Multilobe gears can be derived from unilobe gears. In appropriate situations, elliptical gears may be cascaded to obtain varying speed-change characteristics, giving an effective ratio of from 1 to K^2 . Bilobe gears (oval gears) have been used in flowmeters and pumps. Using precision elliptical bilobe gears, flowmeters can have good linearity over a wide range of flow rates and viscosities -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

At 10:27 AM 6/15/2004 -0400, Fred Hillhouse wrote: >Some employees at a company that I was once employed at built a clock using elliptical gears as joke. The owner thought that everyone should be at work ALL the time. Joke was that the hands would slow down during the work day. I am not sure how it really worked out though. It looked cool at least. Didn't analog computers, like the norden bombsight, use this sort of thing? -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

A friend of mine used to work for a firm making labelling machines. They had to build one to put a label on a bottle with a wide oval shape (it was for some sort of cosmetic, like hand-cream) where the major axis was about 4x the minor. He discovered (although I'm sure other people knew before) that a pair of same-sized (circular) gears mounted eccentrically and properly meshed have an overall 1:1 ratio per revolution, but the movement of the output is non-linear in relation to the input within each revolution. It was just what he needed to rotate the bottle in time with the feeding of the label onto it (that is it rotated the bottle to give a linear feed of the circumference past a given point despite it being non-circular). Cheers, Howard Winter St.Albans, England -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

{Quote hidden}>-----Original Message----- >From: Howard Winter [HDRWKILLspamH2ORG.DEMON.CO.UK] >Sent: 17 June 2004 10:15 >To: .....PICLISTKILLspam.....MITVMA.MIT.EDU >Subject: Re: [OT:] Non circular gears > > >A friend of mine used to work for a firm making >labelling machines. They had to build one to put a >label on a bottle with a wide oval shape (it was for >some sort of cosmetic, like hand-cream) where the major >axis was about 4x the minor. > >He discovered (although I'm sure other people knew >before) that a pair of same-sized (circular) gears >mounted eccentrically and properly meshed have an >overall 1:1 ratio per revolution, but the movement of >the output is non-linear in relation to the input within >each revolution. It was just what he needed to rotate >the bottle in time with the feeding of the label onto it >(that is it rotated the bottle to give a linear feed of >the circumference past a given point despite it being non-circular). The same effect is used on push bikes which have ellipitcal sprockets to help keep the rear wheel torque more constant throughout each stroke. Not sure if these are still in favour, but they were a big thing some years ago. Regards Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. ======================================================================= Any questions about Bookham's E-Mail service should be directed to EraseMEpostmasterspam_OUTTakeThisOuTbookham.com. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.