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dirty clutch trick

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brian jones 1125/06/2021 14:10:28
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309 forum posts
56 photos

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

Nigel Graham 225/06/2021 14:16:22
1676 forum posts
20 photos

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.

John Baron25/06/2021 15:27:37
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487 forum posts
189 photos

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.

AJW25/06/2021 15:35:04
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359 forum posts
135 photos

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

Alan

not done it yet25/06/2021 15:56:34
6280 forum posts
20 photos

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.

john fletcher 125/06/2021 16:06:00
718 forum posts

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

Jon Lawes25/06/2021 16:41:05
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636 forum posts

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

DMB25/06/2021 17:12:14
1154 forum posts
1 photos

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.

ega25/06/2021 17:55:15
2242 forum posts
186 photos
Posted by DMB on 25/06/2021 17:12:14:

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?

Howard Lewis25/06/2021 18:50:24
5237 forum posts
13 photos

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

Bill Davies 225/06/2021 19:45:41
242 forum posts
11 photos

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

Myford Tri-Lever descritption

Bill

Steviegtr25/06/2021 20:00:05
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2225 forum posts
311 photos

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

Steve.

Mick Dobson25/06/2021 21:11:11
35 forum posts
20 photos

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.

img_20200907_194143537.jpg

ega26/06/2021 00:05:17
2242 forum posts
186 photos
Posted by Bill Davies 2 on 25/06/2021 19:45:41:

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

Myford Tri-Lever descritption

Bill

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

ega26/06/2021 10:41:03
2242 forum posts
186 photos

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

OuBallie30/06/2021 12:16:54
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1156 forum posts
661 photos

Ray MacMahon device in action on my BH600G:

Warco BH600G Clutch
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

Howard Lewis30/06/2021 22:20:58
5237 forum posts
13 photos

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

Jonathon Bywater01/07/2021 08:14:38
18 forum posts

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!

Nigel McBurney 101/07/2021 09:11:49
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911 forum posts
3 photos

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.

OuBallie01/07/2021 16:37:08
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1156 forum posts
661 photos

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!

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