65 Kw Alternator Centrifugal clutch?

[George]

Hello again.

My combined heat and power project has progressed a bit. I have run the lathe on it and the governed fuel injector pump seems to work a treat. The frequency only varies about one cycle a second and the voltage hardly varies at all. I am quite happy with that. However, starting the Perkins P3 with the belted drive engaged is too hard on the starter and the drive. What it needs is a centrifugal clutch. I am sure of that now and I have started thinking of how to achieve this.

For a start I have got rid of the belt tensioner and the drive shaft from the flywheel. I shall move the alternator back a bit to make room for a centrifugal clutch and a stouter shaft and support bearing (s). It is only one inch keyed shaft at the moment and already the keyway is starting to show the effects of the diesel trying to start and being lashed backwards and forwards by the weight of the alternator rotor. It starts fine with the belts off, but even with the belts very loose - as I had a belt tensioner for after the Perkins started, they still dig into the pulleis and grip even though extremely loose and in some danger of coming off. It is not satisfactory.

There are various designs available on the web, and I have already "collected" a few bits like an old brake drum plus shoes and a lot of ideas, However maybe the quickest and cheapest option would be to try and find one off an old dumper and make up flanges to allow it to be put in the space between the flywheel of the Perkins and the belt pulley on the alternator. Does anyone know of a centrifugal clutch fitted to any suitable machine that can handle about 25 Hp at 1000, rpm? Or even have something suitable in Norfolk or at least East Anglia. I fear making one will add weeks to the job and I need to get it out of the workshop as, It may be that Spring is coming.

Instruments and the controls are fairly straightforward and can be left anyway, if it is actually useable. Can anyone help, please?

Regards George.

maribelecosystems.com (old engines).

[andrew]

Clutch out of a scorpion light tank, it normally transmits power from a jag

4.2.

I'm surprised at the problems with using the multi vee belt as a clutch, it seemed to work fine on the pto of the 400hp mulcher I drove, when tracking between jobs there was no indication the belts were over heating, it did squeal a bit as it engaged (using a hydraulic piston on the tensioner).

AJH

[Harry Bloomfield]

George formulated the question :

A torque converter, as in an automatic gearbox. A magnetic clutch. A normal car friction clutch...

[Harry Bloomfield]

Much smaller, but my tractor/mower uses the V belts as a clutch.

[George]

I think it would work if the pullies were smaller diameter and perhaps running faster. Because the engine jerks a bit when it is starting as it goes over the 3 compressions, the belts have time to drop into the pulley slots and grip. I have a Condor mower with a belt clutch and it works fine. The problem is only starting the engine. If I take the belts off and start it and let it runs light and warm up I can put the belts back on loose and it will start on the first compression and then the belts slip and scream and I can tighten them with my patented belt idler for 3 belts and away it goes, with no problem. They do not even warm up. In cold weather especially, it need to be free of the drag of even loose belts to grind into life. With about half a ton of rotor, albeit with very loose belts, the friction is still such that it jerks about and does not get up to a speed at which it will start. I think a simple dog clutch that I could use to start it and then let it warm up, would probably work, but that would be as hard to fabricate as a centrifugal device, which should do the job. I want it to start to engage at about 750 rpm and be full locked at about 900 so there is no slip at 1000. I don't have access to tanks here, unfortunately.

Regards George.

[andrew]

I hesitate to make suggestions as I'm not an engineer of any sort but:

I never looked at the belt clutch properly but it sounds like you need to configure it to allow the natural roundness of the belts to spring them off more. This suggests both that the drive pulley should be below the driven one and possibly two idlers at 10 o'clock and 2 o'clock on the driven one to keep the belt down. These idlers would not be in play when running. Plus of course more movement on the tensioner.

Parts often come up cheap when they are broken but I mentioned it as a place to start looking because they're probably used elsewhere.

AJH

[Jules Richardson]

I'm coming into this somewhere other than the beginning, which is never good :-) what's the issue - too much drag on the alternator bearings or something? (I assume you're trying to start it with the alternator isolated from the eventual load! ;-)

cheers

Jules

[Andrew Mawson]

bearing

Perkins

Can you not have a small donkey motor to spin the rotor up to speed before engaging the clutch be it loose belt or even a conventional car type clutch ?

AWEM

[Dave Liquorice]

Arrange things so that gravity isn't a problem? Have an idler on the tensioner lift the belts when not tensioning?

[George]

The subject was brought up here previously. Look for 65 Kva Alternator - or 65 Kw ? I have pictures of it on my website:

. Personal Stuff - Old Engines. All is revealed there. Regards George.

[Phil]

ibelecosystems.com=A0. =A0 =A0Personal Stuff =A0- Old Engines. =A0All is

For convenience, I'd go for a magnetic clutch/brake unit powered from the alternator supply (think about it, engages automatically when up to speed). Otherwise, did you know that you have a 65kW starter motor attached?

Phil.

[George]

aribelecosystems.com=A0. =A0 =A0Personal Stuff =A0- Old Engines. =A0All is

I am open to all suggestions Phil, but the alternator is stationary to start with and I do not have a spare 3 phase supply to use it to start the diesel. It is also to be used as a standbye supply, if the single phase mains goes off! I have a 12 volt magnetic clutch that came from an a/c compressor, but I doubt if it would transmit 25 Hp.

I went round a lot of promising places today in Norwich, but without any real success. They wanted to know which device it was supposed to be used on and when I tried to explain they rapidly lost interest and suggested I go somewhere else. I may try and price a clutch for the P3, but it is over 50 years old. I think I shall have to make my own centrifugal one. I now have 3 feet of 45 mm machined shaft, an old Renault brake drum with some LandRover shoes which seem to fit and lots of useful bits of metal in my workshop.

Regards George.

[Thomas Prufer]

I recall something called a "fluid coupling" which may fit the bill: no-load starting, bit-less-than-solid coupling at speed... which might be a nuisance, or might make things run smoother.

Thomas Prufer

[Jules Richardson]

Aha, yes... I moved computers and didn't pick up the previous thread on the new system.

I'm trying to think where you might find a nice, self-contained clutch (other than adapting one from a car). Maybe an old overdrive unit, assuming you can disable one of the ratios so that in that 'gear' the output shaft no longer turns?

Pre-heating the engine oil perhaps isn't a bad idea - you could run a block / sump heater 24x7 from the AC, assuming the alternator's permanently sited where there's power (i.e. it's not intended as a portable unit). Maybe some testing is worth it (heat with a blow lamp), just to see if that would actually help the starter.

Maybe a bigger starter motor's even an option? There looks to be quite a bit of space around your flywheel...

I think adapting a regular car clutch to your flywheel would be a lot easier than using brake parts (and hence trying to allow all the parts to rotate while maintaining hydraulic pressure - unless you were planning on running things via a diff and braking one shaft?)

(nice project, though - I'd love to find a big old alternator like that!)

cheers

Jules

[Rick... (The other Rick)]

website:

   Personal Stuff  - Old Engines.  All is

Go to

a look at the White Cliffs Report and see how they did it.

Rick... (The other Rick)

[George]

ibelecosystems.com=A0. =A0 =A0Personal Stuff =A0- Old Engines. =A0All is

Hi (The other Rick) I think the link has been taken down, - it says it does not exist.

I think a fluid flywheel would work, but where would I get one? Then there is the slippage that you get with one of these. It would vary with the load too, giving a poor frequency regulation. Once a centrifugal clutch reaches it's lock up speed, it does just that and would not slip unless the load brought down the engines speed, - at which time it would not matter as this would be a big overload anyway. In other words a good safety feature.

I saw a centrifugal clutch on an old dumper truck, but they would not let me have it! I may come across one but I am resigned to making one now. I fear it will take a while. There is a lot of fabrication to do and I am still looking for bits, I am a bit of an amateur at lathe and mill work too. I was a radar, low frequency transmitters, electronics, computer and electrics man before, but never mechanical!

The starter motor is not the one for this engine to begin with. I had to modify one that was (is) the spare for a 40 Kw generator set that I have which works, but is incredibly noisy and air cooled, not quite what I had in mind. The starter is plenty strong enough for starting this engine when it is light, but the thought of getting another and possibly having to make up another support plate and lining it all up again, puts me off. In line operation did not work well so I changed that to a geared up belt system. apart from starting the engine it works very well once started. I shall get this centrifuge to work if it kills me.

First trick, move the alternator back a foot or so to make more room. Then change the shaft to a thicker one, supported at the ends and modify the brake drum to run on a bearing and attach it to the drive belt. A flange to bolt on the flywheel with the expanding shoes supported on it in such a way that allows the shoes to expand out into the drum against springs. Fiddle with the springs and weight of the shoes to get it to be free up to 700 rpm and to lock up at about 900 rpm and - as they say Bob's your uncle.

Chicken runs and hedges stopped play today. What I need is some more snow!

Regards George.

[Tim Lamb]

The OP has not said which P3 engine he has. Perkins motors were fitted to several small tractors of 1950's vintage and even found their way into Landrover conversions. Clutch spares ought to be available to supply the classic tractor market. Failing that, the monthly machinery sale at Ely (Cheffins) isn't that far from Norfuk:-)

regards

[Dave Liquorice]

Would the handbrake assembly from a Land Rover help in mounting things? Being shaft mounted already it might, just a thought.

[Harry Bloomfield]

George explained :

Bramar's.

[George]

search did not reveal anything.

Regards George.