Friction (clutch) lining

Maybe

Nick

I assume you cant adapt an existing (car) clutch plate?

I have some surplus clutch plates if that would help, I suppose you could drill the rivets and steal the friction lining? can you use a metal on metal clutch? what about brake pads as clutch pads? more info might lead to an easy to obtain answer.

Dave

Diving in the deep end here and may be making it more complex than it needs to be, but 40-50hp sounds like a lot of torque at low speeds, though no mention of speed range. I would first look at the torque required at expected speed. Then use this in frictional coefficient sums for the material (clutch plate / brake lining ?) chosen, to get some idea of surface area required. All the math will be on the web somewhere, as will friction plate mnaterial characteristics. Ideally, run the clutch at the high speed end of the geartrain to minimise the torque, as this is really what defines the surface area required.

Looking at car or m/c clutch components might be a good start, similar bhp. Alternatively, use a dog and / or sprag clutch, which would have no problem handling that sort of power...

Chris

It's for a forrestry winch/dozer blade to be mounted on the front of a tractor driven from the PTO (rated at 540rpm, or possibly 1000rpm if extra speed would be needed).

Inital figures for a 3500kg pull (dead pull, not rolling), with a reel centre diameter of 100mm, gives a torque of 1746Nm at the reel. Now reeling speed is still to be figured out, but probably looking at something in the region of 100 rpm, so with a 5:1 ratio, I'm still looking at 350Nm if I can fit the clutch on the input shaft. Having the clutch on the input shaft is the key to this winch, as I want to minimize stack height of the winch drum/clutch.

The commerical winches have the clutch working directly on the reel, and is a disc of friction material rivetted to the driven sprocket, with the other side pressing directly on the underside of the winch reel.

My main issue is finding the frictional co-effcient figures so I can work out what size of clutch plate would be needed, aswell as a source of suitable material. Dismantling a commercially available clutch is one option, but I still need figures as the torque transmission is going to be pretty critical, as it also acts as a slip clutch for overload protection. The whole lot is going to be hydraulically controlled, so adjusting the pressure of the thrust ram will be done to fine tune the clutch slip point, but I still need to get in the ball park in the first place.

thanks Moray

given space)

speeds, though

required at

clutch on

stack height

protection.

A modern car may be developing (say) 100 HP but it does it at something over 3000 rpm, so the torque is considerably less than your

There is a place supplying friction material in the Holmthorpe estate in Redhill. I just did a google search and found the place. Capel Mills Friction UK Ltd. It was listed on a page of places supplying friction material.

I may be wrong, but my sums say that you are in the range of a motorcycle multiplate wet clutch (I'm thinking Triumph Bonneville or BSA A65 here...).

Conversely, a Ford Focus 2l engine produces 180Nm of torque apparently. So that might give a basis to start looking from.

Mark Rand RTFM

In article , Andrew Mawson writes

From a (not entirely expert) reading of specs, diesel engined cars tend to have higher torque than petrol engined ones. Just looking at the spec for my car (petrol) compared with its diesel equivalent shows torque of

David

No they don't. For a given capacity normally aspirated diesel engines have significantly lower torque and bhp than normally aspirated petrol engines. However, most modern car diesel engines are turbocharged to overcome this limitation. What you then get is a diesel engine that still doesn't rev very high but has high torque and the same bhp per litre as a smaller normally aspirated petrol engine. Of course if you turbocharge the petrol engine you'll then get both higher torque and higher bhp per litre at the same boost level as the diesel engine.

Just looking at the spec

What is your car? Whatever the units 350 and 650 are fecking high torque figures for a car engine. Are you sure you don't drive a railway loco?

I've got a TwinDisc industrial clutch here off a Lister diesel, waiting to go in the scrap. No idea of its capabilities, but you can take it away if it's likely to be any use.

Tim

In article , Dave Baker writes

Audi A8 4.2 Quattro ... and to add insult to injury, I misread the figure for the torque of the petrol engine (it was late!), it is 430 not

Power is 335 "PS", which I understand is a German unit more or less the same as HP, at 6500 rpm.

David

A diesel engine will always have a higher torque than an equivalent petrol, due to the far higher combustion pressures involved. It's just that the diesels max revs are far lower than the equivalent petrol. It's what you do with the torque that matters. By the time the engines geared to similar speeds, torque levels will be fairly similar for any given hp of engine.

My 1.7 diesel is rated at 285Nm, but that's not running that high a boost pressure. The ford 2.2tdci must be putting out a fair amount of torque...

They might manage it a few times, but your average vehicle clutch, doesn't need to be engaged under full torque/load very often. I know the speeds I'm considering burn out shouldn't be an issue, but sheering is. And sheering when you've got a 60ft tree balanced with the winch is not really an option!

I have considered using a clutch plate from a vehicle, but instead of driving it through the centre as it would be in a vehicle, have it so when engaged, it's clamped between the driven and non-driven plates, but I'm not entirely sure how the clutch plate would react. This is still a serious option.

Cheers for that. That's the kind of thing I'm looking for.

moray

You're going to use hydraulic pressure to engage the clutch? Not very good idea from a safety point of view. If pressure falls or the engine stops for any reason, the winch lets go.

BTW MH gives the a co-efficient as .4 for brake type material on cast iron. The formula: Power Transmitted by Disk Clutches. - The approximate amount of power that a disk clutch wi]] transmit may be determined from the following formula, in which:

H = horsepower transmitted by the clutch: p = coefficient of friction; f = mean radius of engaging surfaces; F = axial force in pounds (spring pressure) holding disks in contact; N = number of frictional surfaces; S = speed of shaft in revolutions per minute:

prFNS H =------- 63,000

BTW p was not strictly "p" but an open topped "p"

Tom

That's the whole idea. Should anything go wrong, it's far safer for the winch to stop, and the brake to come on (the winch will have a band brake operating directly on the winch reel, which needs hydraulic pressure to release). Even the mechanically operated winches need to be held in drive.

Thanks for that. I've got that in a college textbook somewhere, but it'll save me having to find it! Only issue is with the co-efficient spec,as I'll be using steel. I'm guessing that there won't be much difference from cast iron, as steel is used for some brakes, but I've yet to find a source that will confirm that.

moray

It will be interesting to see how the clutch apply pressure will be balanced against the brake release pressure so that there is simultaneous release of one and the application of the other. Especially when a bit of wear & tear takes place. Perhaps the odd accumulator will be required. Inadvertent release of winch ropes before brakes take up can be a trifle disconcerting.

FWIW steel on cast iron has the same CoF @ .4

Tom

The clutch and brake will be operated of seperate spools using closed centre hyrdraulics, which will at a later date have electrical control added (for remote operation) I know the commercial units somehow manage it of one control, but I'm not entirely sure how they manage to compensate for different loads on the winch to get a smooth transition from braked to pulling or unreeling. I know it can be done using some extra mechanicals, which I will be allowing for adding at a later date if needed.

I eventually found that after much googling last night. Can do what I want with a 200mm diameter clutch, but applying the force required is going to need a bit of a rethink, as I suffered a bit of brain fade when thinking about the pressure needed to release a standard diaphragm clutch plate (totally forgot about the leverage ratio for the fingers, and the resultant actual force on the clutch!).

Just need to get some proper design drawings done, and make sure everything is going to fit in on paper, then I can start cutting some metal, rather than my usual approach of working it out as I go.

thanks moray

For good reasons. >

Meanwhile safety is compromised.

What they manage, and how it actually works are two very different things. And having just found a parts diagram, those with the brake option, use two seperate controls, unless you go for the remote option, where they can sneak in a some electronic wizardy to help provide a smooth transition, which is part of my long term plan.

Not anymore than a manually operated one. With a manually operated winch, you've got two levers. One for the brake (that's if theres one fitted, as the brake is optional on quite a lot of winches), and one for the clutch. You can get the timing just as wrong with two manual levers, than you can with two hydraulic spool valves.

I know the importance of safety, and getting a machine that does the job, how we want it done without failing is the top priority. If you've ever been on site, when the winch that's supposed to pull 3.5t decides it's not going to when you've just cut through the trunk of a 50 foot tree, you'd soon understand why failure is not an option.

And in case you're wondering why a commercial winch isn't an option, we want a custom set-up on the front of the tractor that minimises how far it sticks out the front, and can also accomodate the PTO which isn't positioned suitably for commercial winches.