Union Jubilee Clutch.

[Yorkie]

Ok, here's another, hows about a variable pulley, something along the lines of the old DAF Variomatc...
Lawrence.

That variomatic drive was a wonderful system. In the late 1960s I had a Raleigh 'Ultramatic' moped which I used to commute to the train station in Nottingham - about five miles each way. For a year, in 1968 I used to travel daily by train down to Northampton - about 100 miles. (£3.00 a day expenses, and a monthly season ticket was £11.00! The only thing that kept me sane was that to my ears, the train wheels didn't rhythmically go 'diddly dum, diddly dum', but 'three pounds a day, three pounds a day'!). I used to ride to the station, chain the moped to the railings, do the return train journey, then ride home on the moped. On Fridays, I left it chained to the railings over the weekend, drove my car down to Northampton and used it to drive around on business during the week, driving it back home on Friday afternoon. I guess that nowadays, some jobsworth or another would be down on me saying’ you can't leave that chained up there' or slapping a ticket on it.

The Ultramtic was a splendid steed. One kick on the pedals and it started right away. No clutch - just a throttle. It ticked over like a sewing machine and at tickover, the belt slipped so it was like being in 'neutral', but as soon as you opened the throttle, the two halves of the pulley came together by centrifugal force and were loaded with quite large metal balls which - as the speed increased - had the effect of pulling the halves of the pulley closer together so that the diameter of the pulley varied smoothly from minimum to maximum diameter as the belt rode up the pulley. The engine was mounted on springs to enable it to move as the belt pulled the engine backwards as the pulley grew infinitely larger towards maximum diameter. Never skipped a beat.

This was back in the days when mopeds weren't restricted and the 'Ultramatic' would top out at about 45MPH. It was a real joy to ride and I rather wished I'd kept it, but when the need for it no longer existed, it just became clutter so it had to go.

I'm rather surprised that more use isn't made of that system - no clutch no gearbox, smoothly variable speed - what's not to like?

For lathe speed control they seem to have gone down the electronic route, often using inverters/3-phase motors. The lathe that we have at our woodturning club has the motor within the headstock and the drive shaft integral to the motor, the speed being varied electronically with a built-in inverter. It gets quite hot in use and if the motor or electronics fail, basically, the lathe would be a write-off. I'm just glad it isn't mine. I have the same make of lathe, but with a 1.5HP motor driving a eight-speed pulley. It only takes a couple of minutes to change the speed but would be much more convenient if it was variable. Often you need to turn at high speed - say 2000+ rpm, but then a much slower speed (say 300 RPM to sand an item or you risk cracking the wood through overheating it. I'm unlikely to ever need 1.5HP, though the headstock can be swung out and an outrigger used to enable larger diameter items up to 29" diam, (a spinning wheel for example or large platter) to be turned.

As I'm left-handed, it is handy to be able to swivel the head outwards from the bed when hollowing out bowls, but as it has a 16" capacity over the bed, for anyone right-handed, it would cope with most things most turners would want to turn. (The lathe model is '16-44', which means that it has a 16" swing over the bed, and can be extended to 44" between centres for spindle work). When I switch the motor off, I can slow the lathe to a halt with my hand as on the other end of the headstock shaft I have a hand-wheel. It takes ages to slow down to a halt if it has say a large bowl on it. 'Officially', the hand-wheel is meant for turning the shaft with the lathe switched off when using the indexing mechanism, but what the heck - everyone with a hand-wheel does it, (while they still have a hand to do it with!).

I don't want to take Colin's thread too far off topic, but I've attached a few pics of my lathe and motor/pulley arrangements. Think how much more convenient it would be if it had a simple 'variomatic' drive rather than an eight-stepped pulley or, an expensive and complicated invertor/3-phase motor arrangement such as on the Nova DVR-XP. None of which is of any help or relevance to Colin in his quest for a clutch arrangement for his Jubilee. Sorry about that!