dirty clutch trick

I have an ML7 and as you know im sure, switching a motor on/off many times/hour stresses the motor and makes it how

I havent the misfortune to have a Myford clutch (Ive read horro stories about this on here)

Here' my cheap charlie way round the problem (maybe you all know this already, but I havent seen it posted)

I use the layshaft lever to loosen the belt drive and act as a clutch. Its worked fine for me for 5+ years and only last week had to put a new main belt on (ca £1.75 btw)

I daresay there will be purists who will throw hands up in horror - but it was good for me and beats stressing the motor

Hope this helps

Well, something like this is used on horticultural machines more powerful than an ML7 motor, and provided it does not unduly wear the pulleys, as you say a belt is a lot cheaper than a motor.

Hi Brian, Guys,

I've not heard any horror stories about Myford clutches, but slipping a belt is a useful trick ! I deliberately run mine a little loose.

I've used that method for the last 35 years! All fine!

Alan

I would expect any drive with the motor at the lowest point to be the best situation for a totally slack belt. Gravity helps the belt clear the pulley.

Flat belts with ‘fast and loose’ pulleys were a common item as a clutch in ye olde days. The tractor driven saw bench was one example. Our 1950s baler had two slack belts with jockey-wheel tensioners. A flat belt for the main drive (but had the engine idled down, if the drive was disengaged for long) and a single V belt on the pick-up mechanism (rotating tines, elevator, screw feed to the bale chamber) and fan for the knotter assembly. The V belt was never left turning loose, for long.

Slipping belts is really no substitute for a proper sized shear pin/bolt, IMO.

I had a ML7 and made a clutch for it, by following an article in MEW, it worked fine, no trouble at all, I think I still have the article and details. In the early days of combined harvesters some had their main power application by a slipping belt. In about 1960 a belt for combined harvesters £37 I remember the grimace on the farmers face when told it was £37 and no grant either. Some building site dumper had the same idea ,.a simple single cylinder diesel engine, a belt, back axle and two pulleys. John

I use this exact technique for cutting threads (when using a tap or die, obviously....).

Same principle used by Myfords on their tri - lever ML7. Three slack belts with one at a time tensioner by jockey pulley actuated by a lever, hence "tri-lever." They were the final drive to the mandrel. Good at the time but old hat now, thanks to VFD.

Am I right in thinking that the two slack non-driving belts were trapped clear of the pulleys in some way ie not *just* slack?

Slackening the belt, to use it as a clutch, is not unusual, on all sorts of machinery.

Some time ago, a simple modification, used slackening the belt as a form of clutch on the Warco BH600.

IIRC it was designed and made by Brian MacMahon.

For anyone who wants to look through back numbers of M E W , it could be implemented on any of the clones of the Taiwanese lathes, such as the Chester Craftsman, Engineers Tool Room, BL12 - 243 etc.

Something similar could be applied to almost any lathe using V belt drive, possibly even flat belt drive?

Howard

Slightly off-topic, here is a description of the Myford Tri-Lever:

Myford Tri-Lever descritption

Bill

Some ride on lawnmowers use the same principal for the drive cutters.

Steve.

On my Portass lathe with flat belt drive I arranged the motor and countershaft plate to hinge at the bottom. The belt tension is set by use of a car handbrake lever with ratchet and a link rod to the countershaft plate. Easy to de-clutch or change speed on the fly.

Thanks for the link which seems to show I was wrong in my earlier post (I have better success in spelling its name!)

PS The Tri-Leva in the video has an interesting non-Myford gearbox - possibly a Sparey.

Ray MacMahon device in action on my BH600G:

The lever was my ‘design’.

Geoff - Play halted due to my stupidity.

Edited By OuBallie on 30/06/2021 12:18:10

Edited By OuBallie on 30/06/2021 12:19:06

Thanks Geoff for correcting my half right memory!

At least we both had the same device in mind.

How's the Seven rebuild progressing? Give us an update, please

Howard

My ML 10 arrived with a lever on the countershaft and sprung motor mount,as did a Flexispeed I have.

Unfortunately its not slack enough to safely stop motor and so much fiddling and moving things for a slightly longer belt so I m going to make a clutch!

The 42 inch deck drive on my mower is a tight /slack belt clutch, the belt, which recently broke after 16 years. there was no real wear on the pulleys and thats with a 17 hp Kawazaki ,who would have thought that when I was a youngster that lawn mowers in the future would have 17 hp v twins. regarding the myford clutch my S7 clutch has been ok for near 50 years with the original drive belts.

Hello Howard,

No progress on the Seven unfortunately due to health and a contra temp with front door.
Was just about to get back onto the Austin, when on the 14 June I amputated the tip of my left thumb, removing a bit of bone and tearing the nail off when I stuck it in the hinge side of the door jam and then tried to close it.
Plastic surgery took place on the 17th, resulting in me now having half the length of nail once it grows back.

Geoff - Stupidity knows no bounds!