Stalwart Inter-Axle Viscous Couplings?

[listerdiesel]

In an idle moment at lunchtime, I was looking at Rick Salmon's Stalwart:

 

http://www.milweb.org/classifieds/large_image.php?ad=57952&cat=4

 

and after a look up of the vehicle spec's, which make ir look a bit underpowered with 220bhp for 9 tons, I went on to the transmission.

 

It seems that there is no design allowance for axle rotational speeds to differ, and wind-up is the result.

 

Looking at one of the line drawings on the web, it seems that if you could put a viscous coupling between the axles, with provision to lock them up if required, it would make life a lot easier for road driving and the bevel boxes, which must take an absolute hammering on hard surfaces.

 

This sort of thing does it automatically if the rotational speed differs by more than 6%, more than enough

 

http://www.syncro.org/VCTest.html

 

The snag here is that there is little drive in 'normal conditions, but is that a problem?

 

If the coupling was in the side drives from centre to front and centre to rear, four couplings, the main drive would be to the centre axle, and the to the others if the speed differential was over the 6%.

 

It might need a coupling with a preset drive figure and slippage if that is exceeded, but the basics seem to work out.

 

I haven't got a Stolly, yet, but it's the sort of thing I'd like to implement, thus allowing easier transport.

 

Thoughts?

 

Peter

[Grumpy]

This sort of thing has been done before but with air operated dog clutches. The main problem is there is very little clearance between the drive shafts and the hull (about an inch), another problem is by reducing drive to the outer bevel boxes places more load on the cetre ones.

 

99% of bevel box failures are due to poor maintenance or shock loads, wind up is not as bad as everyone makes out. The most important thing is equalizing tyre circumference on each side and tyres pressures. Another Stolly quirk is the centre bevel boxes are fed from the transfer box, the oil dip stick is marked wrong and if filled to this mark the bevel boxes will be starved of oil, the oil needs to be about an inch above the level mark.

 

The bar grips tyres don’t give the best of traction on the road and help alleviate the problem. I’ve had a Stolly since 93 and driven hundreds of road miles, never had a failure due to wind up – reaching out to touch some wood quickly.

:thumbsup:

[Gordon_M]

It's been done, I think.

 

I believe the Budge diesel Stolly had four viscous couplings on each of the four 'corner' wheel drive units. Only the centre axle was driven directly as original.

 

Anyone ?

[Grumpy]

It's been done, I think.

 

I believe the Budge diesel Stolly had four viscous couplings on each of the four 'corner' wheel drive units. Only the centre axle was driven directly as original.

 

Anyone ?

 

Yes STAL2-708 had four couplins - not sure if they were viscous or not - There was also a French owner that fitted four dog clutches, I'll see if I can dig out the pictures he sent me and scan them to post here

Edited September 30, 2011 by Grumpy

[listerdiesel]

Thanks, guys, all useful stuff.

 

Has anyone tried fuel injection and/or LPG on the B81?

 

Looking at the Bosch Motronic system, it could work, given the extra sensors required.

 

What is the firing order of the B81, 'standard in-line 8' 16256374 or something different?

 

Peter

Edited October 1, 2011 by listerdiesel

[Jerrykins]

Peter

R-R Crewe made a G81 & G61 gas powered versions of the B range, they used an Imco carburetter and the LPG versions lasted better on LPG and the like than Natural gas. For endurance testing a deal was struck with a Teeside bus company and I've found an article about it on http://www.chiefofficers.net/888333888/cms/index.php/news/special_interest/active_planet/alternative_power/gas_powered_public_transport_how_it_began which may be helpful, I remember the bus visiting Crewe from time to time.

The G range didn't sell brilliantly partly because the B range was by then an old lady and expensive to buy, but also most users drove them like diesels and never bothered to change down, when the petrol derived engine was screaming to spin a little more. As the article said they were silent compared to a diesel. The project and sales quietly faded away.

Jerry

[listerdiesel]

That was interesting! Many thanks.

 

I was looking at multi-point fuel and gas rather than the IMPCO single point system, mainly due to the economies of using petrol injection and the ease of converting to LPG and back again, you just change the solenoid drivers from the petrol injectors to the gas injectors, so no need to run the carb out of petrol before switching onto gas, and the same coming back, you don't need to wait for the carb float chamber to fill up.

 

It's all just interest at present, but the iron head B81 would be fine on LPG, just might need the exhaust valve seats checking over.

 

Peter

[Richard Farrant]

That was interesting! Many thanks.

 

I was looking at multi-point fuel and gas rather than the IMPCO single point system, mainly due to the economies of using petrol injection and the ease of converting to LPG and back again, you just change the solenoid drivers from the petrol injectors to the gas injectors, so no need to run the carb out of petrol before switching onto gas, and the same coming back, you don't need to wait for the carb float chamber to fill up.

 

It's all just interest at present, but the iron head B81 would be fine on LPG, just might need the exhaust valve seats checking over.

 

Peter

 

Hi Peter,

 

I met a Stalwart owner at a military vehicle event in Australia, earlier this year. He has done extensive mods to his vehicle, including fitting a higher ratio gear train in the transfer box, giving him a road speed of around 60 mph. He has also fitted a declutch system to bevel boxes, forgot at present how he did that, but think it is only the leading axle that can be disconnected. He has a LPG conversion on it, and this is where you will want to know. On the long run up to Corowa from Melbourne, he was suffering icing when running on gas, and had removed the large fuel tank for a small one for starting up, so had to keep topping up the petrol tank and run on petrol more than he intended. Not sure if he is on this forum, but comes from Geelong in Victoria.

 

regards, Richard

[listerdiesel]

Cheers, Richard, I'd guess that he was using a single point carb system and a relatively crude vapouriser to get that icing, caused by the heat input needed to vapourise the quantities of LPG being consumed.

 

Most modern systems are using a vapouriser heated from the engine cooling system, and with multi-point injection any additional heat loss is spread over 8 injectors and pipes, so icing isn't a problem.

 

I'd guess at £50k to get one of these in good mechanical and bodily nick, perhaps less if you had a donor vehicle for spares?

 

Peter

[Amphibi boy]

There was a stolly with a v8 diesel, that had couplings to engage/disengage drive to the axles, not sure if it was from Ireland, someone on here will know more about it, did see some photo's but can't remember where now.

 

As for the l.p.g I've seen a few with this conversion, but I think it was just the normal system and not injected.

 

But I like the idea of a fuel injected b series, I'm sure it could be done.

 

Cheers

Shaun

[listerdiesel]

Shaun:

 

Thanks for the input, I was thinking on the lines of an existing sensor set and then modifying a normal V8 ECU to run the thing.

 

The Bosch Motronic system is one of the most reliable and lends itself to some tweaking, the main issue is getting the firing sequencing right, and you would also do away with the distributor as the Motronic uses a coil pack directly driven from the ECU, either 4 X 1 coil or the 2 X 2 coil, with lost spark ignition, as on the Rover V8.

 

The benefits would be better fuel consumption and cleaner emissions, plus of course you could then fit LPG quite easily.

 

Peter

[101 Ron]

[listerdiesel]

Thanks for the pic's, Ron, is that an IMPCO setup, or home-brewed?

 

Peter

[101 Ron]

Thanks for the pic's, Ron, is that an IMPCO setup, or home-brewed?

 

Peter

The pics has a Impco system and the small brake diaphram chambers are for the shaft disconnects.

 

I personally will use different impco components on my Stolly when it comes time to put gas on it.

Impco has made LP gas components for large engines since the 1950s.

A 460 Impco mixer would work much better on the B81 rolls

The conversion is easy , it is the fitting of gas tanks without cutting up the vehicle is the issuse as well as hull ventalation if a gas leak develops.

[listerdiesel]

This is the diagram I have been looking for:

 

 

Looks like it might be possible to get down to 2.55metre width legally.

 

Peter

[listerdiesel]

Ron:

 

Thanks for the pictures, have the shafts got simple dog clutches or are they more sophisticated?

 

Peter

[101 Ron]

Ron:

 

Thanks for the pictures, have the shafts got simple dog clutches or are they more sophisticated?

 

Peter

 

[listerdiesel]

Cheers, Ron, looks like they have used the existing splined sleeves and made them mobile.

 

Neat idea to use the small air actuators, they are the sort of thing used on large truck clutches and diff locks, and air is already available on the vehicle.

 

Peter