carvalho@ucbvax.BERKELEY.EDU (Marcio de Carvalho) (11/03/85)
Have anyone heard about this so-called continuous transmission? According to some friends, a car equipped with one was presented in this year's Automobile show in Turin, Italy. As it was described to me, it is basically a pair of controllable variable diameter wheels linked by a belt; which enables the driver to choose among any of the infinitely many transmission ratio possible. Any information would be helpful. Thanks, --Marcio carvalho@ucb-vax.edu ucbvax!carvalho
toma@tekchips.UUCP (Tom Almy) (11/04/85)
In article <10878@ucbvax.BERKELEY.EDU> carvalho@ucbvax.BERKELEY.EDU (Marcio de Carvalho) writes: > > Have anyone heard about this so-called continuous >transmission? ... > As it was described to me, it is basically a pair of >controllable variable diameter wheels linked by a belt; which >enables the driver to choose among any of the infinitely many >transmission ratio possible. These things have been promoted as something new, but my mother had a 1963 (nineteen sixty-three) DAF with one of those transmissions. The car, about the size of a VW Bug, had a 2 opposed cylinder, 30HP, air cooled front engine with a centrifugal clutch, with the transmission in the rear. By having two belts, one for each wheel, no differential was needed, and the resulting "limited slip" operation make it fantastic on snow and ice. But the car had many problems, mostly related to the transmission. (BTW, the cars basic model sold for about $1200, making it one of the cheapest cars available at the time, and by far the cheapest with an automatic transmission which at the time was only available on very few small cars). 1. Belt life was limited to about 8-10k miles. While the car could be driven with one belt missing, it would slip so much that you wouldn't dare stop on a hill. 2. Belt slippage was a problem, especially when wet. 3. Performance was awful, even compared with contemporary small cars. Top speed was about 60, and acceleration was worse than the 40hp VW Buses of the time! Gas mileage was about 30-32 in suburban driving. This car was no match at all for the popular VW Bugs and Renault Dauphines of the time. 4. The transmission (Forward--Neutral--Reverse) had to be shifted swiftly between F and R. Because of the lack of a manual clutch if you stopped in N you couldn't shift it into gear. In this situation you had to turn the engine off, wait about 10 seconds for the driveshaft to stop spinning, put it in gear and restart (YES, you always started the car in gear!). To be fair, I am sure they improved things over the years. After they stopped importing them in the late 60s, DAF switched to a more powerful 4 cylinder engine. The company was purchased by Volvo a few years ago, and the cars are now sold under the Volvo name in Europe. I may need to be corrected on this last statement, since I am not sure. Tom Almy
daw1@mhuxl.UUCP (WILLIAMS) (11/06/85)
> > As it was described to me, it is basically a pair of > controllable variable diameter wheels linked by a belt; which > enables the driver to choose among any of the infinitely many > transmission ratio possible. > They used to have these on minibikes about 12 years ago. You couldn't select for yourself the ratio as it was a function of the engine/vehicle speed/throttle opening. Two centrifugally(sp?) operated v-groove pulleys narrowed and widened to change the overall drive ratio (when one pulley widened the other narrowed). My minibike didn't have one and another kid's did. He always blew me away since he always had the "perfect" gear for the occasion. To handle the output of a car I'm sure that the system is quite different, but the result is the same: a perfect ratio for all occasions! As far as revenge on the hotshoe with the belt drive, I decided more top-end speed would help out. So I disabled the governor on the ol' 3-h.p. Tecumseh. Really helped out the top-end speed; the bottom-end of the engine came out the large hole in the side of the block, however! A couple of years later who do I see? Hotshoe in a 383 Road Runner! Well I figured... 1 Stick-shifts forever, 1 1 1 2 1 Doug Williams 1 3 3 1 AT&T Bell Labs 1 4 6 4 1 Reading, PA 1 5 10 10 5 1 mhuxl!daw1 1 6 15 20 15 6 1
segre@uicsl.UUCP (11/08/85)
When I was living in Italy (80-81) I seem to recall that Fiat was road testing a bunch of Ritmos (Stradas in the US) with this kind of transmission. They gave them to taxi drivers to see how they held up under tough conditions. I don't think this is anything new, as some other (older) European cars* used to have this kind of transmission - the problem was the belts would break rather easily. The newer Fiats had steel belts which weren't supposed to break. Alberto Segre Coordinated Science Lab Univ. of Illinois @ Urbana * I think it was some Dutch manufacturer - is it DAP or something like that?
haapanen@watdcsu.UUCP (Tom Haapanen [DCS]) (11/09/85)
In article <340@tekchips.UUCP> toma@tekchips.UUCP (Tom Almy) writes: >> Have anyone heard about this so-called continuous >>transmission? ... >These things have been promoted as something new, but my mother had a 1963 >(nineteen sixty-three) DAF with one of those transmissions. The car, about >the size of a VW Bug, had a 2 opposed cylinder, 30HP, air cooled front engine >with a centrifugal clutch, with the transmission in the rear. By having two >belts, one for each wheel, no differential was needed, and the resulting >"limited slip" operation make it fantastic on snow and ice. But the car had >many problems, mostly related to the transmission. (BTW, the cars basic >model sold for about $1200, making it one of the cheapest cars available at >the time, and by far the cheapest with an automatic transmission which at the >time was only available on very few small cars). > >1. Belt life was limited to about 8-10k miles. While the car could be driven > with one belt missing, it would slip so much that you wouldn't dare stop > on a hill. > >2. Belt slippage was a problem, especially when wet. > >3. Performance was awful, even compared with contemporary small cars. Top > speed was about 60, and acceleration was worse than the 40hp VW Buses > of the time! Gas mileage was about 30-32 in suburban driving. This car > was no match at all for the popular VW Bugs and Renault Dauphines of the > time. > >4. The transmission (Forward--Neutral--Reverse) had to be shifted swiftly > between F and R. Because of the lack of a manual clutch if you stopped > in N you couldn't shift it into gear. In this situation you had to turn > the engine off, wait about 10 seconds for the driveshaft to stop spinning, > put it in gear and restart (YES, you always started the car in gear!). > >To be fair, I am sure they improved things over the years. After they >stopped importing them in the late 60s, DAF switched to a more powerful 4 >cylinder engine. The company was purchased by Volvo a few years >ago, and the cars are now sold under the Volvo name in Europe. I may need >to be corrected on this last statement, since I am not sure. You're actually very close. Volvo indeed now manufactures CVT models at the old DAF factory. It's a different model, though, and is known as a Volvo 343. It's about the size of a Golf II, and is considerably more civilized than an old DAF. The transmission is still a mechanic's nightmare, though. VW and other companies are working on "second-generation" CVTs. \tom haapanen watmath!watdcsu!haapanen Im all lost in the Supermarket I can no longer shop happily I came in here for that special offer Guaranteed personality (c) The Clash, 1979
ahs@burl.UUCP (Spinks Albert H. ) (11/09/85)
> > Have anyone heard about this so-called continuous > transmission? According to some friends, a car equipped with > one was presented in this year's Automobile show in Turin, > Italy. > As it was described to me, it is basically a pair of > controllable variable diameter wheels linked by a belt; which > enables the driver to choose among any of the infinitely many > transmission ratio possible. > Any information would be helpful. > Thanks, > --Marcio > > carvalho@ucb-vax.edu > ucbvax!carvalho *** REPLACE THIS LINE WITH YOUR MESSAGE *** The type of transmission you have discribed has been used on farm equipment for at least 25 years, especially large grain combines. The system is composed of two variable diameter pulleys with a belt in between. One pulley has a hydrolic cylinder attachment that controls its diameter and the diameter of the second cylinder simply 'follows' the first through a spring loaded arrangement. The hydrolic system is under the control of the operator. This system works quite well; at least the ones that I am familiar with did. No maintenance was ever required, etc. But they were huge; size was not a serious factor on the side of a big piece of field equipment. It is hard for me to picture a manufacturer development anything like the above that would fit in as small a space as our standard car transmissions. -- Albert H. Spinks - 71BU072120
ahs@burl.UUCP (Spinks Albert H. ) (11/09/85)
> > > > Have anyone heard about this so-called continuous > > transmission? According to some friends, a car equipped with > > one was presented in this year's Automobile show in Turin, > > Italy. > > As it was described to me, it is basically a pair of > > controllable variable diameter wheels linked by a belt; which > > enables the driver to choose among any of the infinitely many > > transmission ratio possible. > > Any information would be helpful. > > Thanks, > > --Marcio > > > > carvalho@ucb-vax.edu > > ucbvax!carvalho > > *** REPLACE THIS LINE WITH YOUR MESSAGE *** > The type of transmission you have discribed has been used on farm equipment > for at least 25 years, especially large grain combines. The system is > composed of two variable diameter pulleys with a belt in between. One > pulley has a hydrolic cylinder attachment that controls its diameter > and the diameter of the second cylinder simply 'follows' the first > through a spring loaded arrangement. The hydrolic system is under the control > of the operator. > > This system works quite well; at least the ones that I am familiar with did. > No maintenance was ever required, etc. But they were huge; size was not a > serious factor on the side of a big piece of field equipment. It is hard > for me to picture a manufacturer development anything like the above that > would fit in as small a space as our standard car transmissions. > > -- > > > > > Albert H. Spinks - 71BU072120 *** REPLACE THIS LINE WITH YOUR MESSAGE *** hydraulic instead of hydrolic---sorry about that -- Albert H. Spinks - 71BU072120
kanner@tymix.UUCP (Herb Kanner) (11/11/85)
In article <923@burl.UUCP> ahs@burl.UUCP (Spinks Albert H. ) writes: >> > >> > Have anyone heard about this so-called continuous >> > transmission? According to some friends, a car equipped with >> > one was presented in this year's Automobile show in Turin, >> > Italy. >> > As it was described to me, it is basically a pair of >> > controllable variable diameter wheels linked by a belt; which >> > enables the driver to choose among any of the infinitely many >> > transmission ratio possible. >> > Any information would be helpful. >> > Thanks, >> > --Marcio >> > >> > carvalho@ucb-vax.edu >> > ucbvax!carvalho >> >> *** REPLACE THIS LINE WITH YOUR MESSAGE *** >> The type of transmission you have discribed has been used on farm equipment >> for at least 25 years, especially large grain combines. The system is >> composed of two variable diameter pulleys with a belt in between. One >> pulley has a hydrolic cylinder attachment that controls its diameter >> and the diameter of the second cylinder simply 'follows' the first >> through a spring loaded arrangement. The hydrolic system is under the control >> of the operator. >> >> This system works quite well; at least the ones that I am familiar with did. >> No maintenance was ever required, etc. But they were huge; size was not a >> serious factor on the side of a big piece of field equipment. It is hard >> for me to picture a manufacturer development anything like the above that >> would fit in as small a space as our standard car transmissions. >> I lived in England between 1970 and 1977. Saw quite a few specimens of a car with a continuous transmission. It was called a DAF, and was made in Holland. Used a belt and cone pulleys. I was told that the belt was no more likely to break than an axle on a conventional drive. -- Herb Kanner Tymnet, Inc. ...!hplabs!oliveb!tymix!kanner
ray@othervax.UUCP (Raymond D. Dunn) (11/15/85)
> > As it was described to me, it is basically a pair of > controllable variable diameter wheels linked by a belt; which > enables the driver to choose among any of the infinitely many > transmission ratio possible. > I can't find the original article from which this quote comes, so this may all have been said before, but: The Dutch auto company DAF used to make several models using this transmission technology, which, if I remember correctly, they called the Variomatic. The transmission consists (simply) of two pulleys connected by a V-belt. Each pulley is constructed in two halves, with the belt between the halves: \ ___ / \\_// \ / (edge-on view) /_\ //_\\ / \ The (horizontal in the diagram) distance between the halves determines the effective diameter of the pulley to the V-belt. When each of the two pulleys is adjusted similarly but in the opposite sense, the belt length required to connect them remains the same, but the ratio changes. I do not know what the driver's input to the system was (ideally should the engine run at a fixed optimal speed, and the "gas" pedal control the transmission ratio!!!) Daf was taken over by Volvo about 10-15 years ago, and I do remember that Volvo then continued to produce at least one Volvo'ised styled version. The Dutch plant is still in operation, and I believe there is some major development on another transmission technology in the works. Can any of our European readers bring us up to date? Ray Dunn ..philabs!micomvax!othervax!ray
bl@hplabsb.UUCP (Bruce T. Lowerre) (11/20/85)
> I do not know what the driver's input to the system was (ideally should the > engine run at a fixed optimal speed, and the "gas" pedal control the > transmission ratio!!!) I remember seeing this same system on a go-cart. Yes, it worked just the way you said. The engine ran at a fixed optimal speed and the "gas" pedal controlled the transmission ratio, however not the way you think. The variable clutch pully acted like a governor. As the engine speed increased, the transmission ration would change to try to speed up the wheels, thus putting a greater load on the engine.