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  • pcarpenter
    replied
    This would seem to be just a variation on a more standard Reeve's drive. The difference is that it's using one more pulley. The premise is the same no matter what....the ratio of the two pulleys changes based on the spacing of the two faces of the pulley. The way that spacing is varied is what changes from one design to the next.

    In machine tools this is varied with a lever or other arrangement. I have a Sheldon shaper that slides the motor back and forth on a pair of round rails. In that case the wide VS belt is wide enough that only the motor end has a v-shaped spring-tensioned sheave. The other end goes around a large, flat pulley and the flat portion of the belt is what bears on that pulley. This is probably the simplest design as changing the distance from the motor to driven pulley is all that's needed. I would think that this could be applied to something like a drill press very easily.

    In the case of the one in my Bridgeport mill, both ends (drive and driven have spring tensioned sheaves and a lever is responsible for changing the spacing of the sheaves by pulling them apart, directly...and only on the driven (spindle) end. The drive end pulley (on the motor shaft) is spring loaded merely to take up the slack.

    In things like snomobiles and ATV's where this has been used for decades, the input throttle of the driving motor varies and centrifugal spring weights on the "primary" side sheave/clutch arrangement determine the rate of change in pulley ratio. In that situation, both the drive pulley and the driven pulley change diameters so you can go from say a 5:1...down to a 1:1 ratio...and keep going to a 1:5 ratio the other direction...giving you *huge* amounts of variability.

    I am sure there is some loss...thus the heat generated, on the other hand, these are transmitting up to several horsepower, so the use of one of the standard variable speed belts both allows for this extra HP as well as allowing for changing ratios. This comes with added surface area...and added friction from pulleys that are gripping the belt under tension.

    As for the cost....I would say that if a guy was designing one of these from scratch and was not constrained by space, you could design around the belt somewhat and use some item you can find surplus. I found several in a bin at a local surplus place I frequent, some years back...but they didn't fit anything I had. For reference...the standard item for a Bridgeport VS head is somewhere in the $70 range. The much larger belt for my Sheldon shaper was $180 as I recall. I hope mine lasts forever.

    Paul

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  • acourtjester
    replied
    variable speed

    My George I think we are on the same page now.

    Can anyone find the construction article for building one of these systems?? I was in either Home Shop Machinist or Machinist Workshop.

    Have fun
    Tom

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  • Peter.
    replied
    Looks to me like the middle part of the the double-pulley on the idler assembly is free to move up-down, and moving the lever on the left upwards hinges the idler assembly towards the motor and the two belts self-compensate. Clever idea.

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  • lazlo
    replied
    Originally posted by acourtjester
    I am posting the pictures so other may better understand the quest.

    Thanks again and have fun
    Tom, that looks like he added an intermediate jockey-pulley to reduce the speed of a wood-working drill press to metalworking speeds.
    In other words, it looks like that's just a conventional V-belt pulley.

    Didn't you say you were looking for a variable-speed Reeve's Drive/CVT?

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  • acourtjester
    replied

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  • acourtjester
    replied
    variable speed

    Hi Geoff

    you da man that is just what I was describing and I did have that issue.
    But there was a construction article posted in either HSM or MW after that and that is what I am looking for so I can build one for my own use.
    I am posting the pictures so other may better understand the quest.

    Thanks again and have fun
    Tom

    http://i896.photobucket.com/albums/a...ress1_0001.jpg
    http://i896.photobucket.com/albums/a...ress1_0002.jpg
    http://i896.photobucket.com/albums/a...ress1_0003.jpg

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  • ammcoman2
    replied
    I think I've found it - it has been bugging me since I first saw your request. Took me a while to go through the old issues as it doesn't show up in the indexes.

    It is under the "Reader's Forum in the Jan/Feb, 2000 issue of the HSM. The submitter is Rouville Labonte of Portales, NM. He mentions and shows photos of the conversion on a drill press and on a Logan lathe. He says the unit is from a MTD lawnmower.

    I seem to remember that he wrote in again giving part #'s but I can't find it.

    Let me know if you need more details.

    Geoff

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  • acourtjester
    replied
    variable speed

    HI All

    I hope now that more info is out about the variable speed changer some one will find the article.

    Lazlo I do not believe they get very hot as they are used in many different systems. I have been told the shopsmith used them and lawn tractors also use them. These would be running for long stretches of time. I think once the speed is set the friction heat would be no more then a normal pulley. I also plan to use it on a low speed system to end up with about 8 to 25 rpm out put. That's my story and I'm sticking to it.

    I need the article to be able to build one!

    Have fun
    Tom

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  • lazlo
    replied
    The belts slide up and down the sidewalls of the Vari-speed sheave as the center distance changes.

    That's the primary loss of efficiency, and why they get so hot...

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  • camdigger
    replied
    I can see how the ratios will change with various postions of the double sheave, but how does the whole set up account for the change in center distances for the different ratios?

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  • acourtjester
    replied
    variator

    HI George
    Thanks it works
    That is a picture I was sent of what I am looking to build. And if I ever get the article I will.

    Have fun
    Tom

    Now to order the other back issues for another projuect.

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  • acourtjester
    replied
    variator test

    HI
    This is a test
    If it were the real thing you would be dirrected to say hello.

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  • lazlo
    replied
    I vaguely remember that HSM article, but I thought it was just an outboard jackshaft that was manually changed? I didn't think it was a Reeves drive?

    Originally posted by DR
    Most of these drives need special, wider v-belts to operate. The belts are stiff and relatively expensive.
    The Vari-speed belts on my Clausing 5914 are about 4 times as wide as a conventional V-belt, and yes, they're very expensive You can probably go cheaper if you find a snowmobile belt. At least, I'd assume that snowmobile belts are cheaper than machinery-branded belts.

    Unless you have some reason to want this type drive specifically I suggest a VFD. The machines I have using this drive were expensive in their day and used it because there were no other viable options. Later versions of the machines use electronic speed control.
    Good advice. Most of us that have VariSpeed machine tools (Bridgeport Varispeeds, Clausing VariSpeed, etc.) wish we didn't

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  • courtjester
    replied
    variable speed

    HI
    Thanks for replys I found one on Ebay and bought it.
    Great to be able to throw out a question and have many answer it.
    I still would like to see the build it yourself article from home shop.
    have fun
    Tom

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  • wierdscience
    replied
    MTD mowers used them,IIRC the aftermarket replacements cost $70.

    Lovejoy makes preety much anything you would ever want,plus they're online catalog has actual dimensions on the parts-

    http://www.lovejoy-inc.com/uploadedF...talogs/vsd.pdf

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