David Herbert

I worked for Fodens in the mid 70s and they were still developing the two stroke engines. I remember a new cylinder block pattern being built in the pattern shop. Also there was considerable co operation between Fodens and RR and they routinely did specialized work for each other. The castings for the prototype RR Wankel tank engine were made by Fodens when I was in the foundry there. This engine showed great promise but never went into production, presumably because of reliability problems. The FD12 was indeed two 6 cylinder engines geared together in much the same way as the Detroit twin 6-71. Actually the whole Foden 2 stroke concept was very much inspired by the Detroit 2 stroke and if anything was even louder ! David

My gut feel is that the open spoke wheel is the earliest, then the very closed wheel then the two round hole wheels. My reason is that the brake ventilation holes get steadily larger which I think would be the natural evolution. The closing of the open spokes and then somewhat opening them up again could be for casting quality reasons. I wonder how many people will notice that you have odd rear wheels when the bus is being displayed ! David

That must have been interesting on the Deltic engine, three cranks rotating in opposite directions to each other ! David

It wasn't the actual fuel that did the damage because they were normally run on diesel. The problem was that to be able to run multifuel the cylinder had to generate pressures and temperatures that would burn low grade fuels but also withstand the much higher pressures and temperatures generated by burning petrol and also unfortunately diesel. This turned out to be rather beyond the metallurgy available. When the multifuel requirement was removed a lot of detail redesign was done to optimize the engine for diesel, particularly on the L60 which had the biggest problem and the reliability went up as did the HP. The increase in HP though was not enough to keep up with the increase in weight of the Chieftain which had had a lower than intended power to weight ratio from the start. The result was the development of the CV12, still used in Challenger 2. David

I understood that the Junkers engine was used in airships not aircraft but have no evidence for this. It is frequently given as the inspiration for the RR engines but again this could be a bit like the story that the Churchill flat 12 engine was two Bedford truck engines bolted together despite the fact that the truck engine made 72hp and the tank engine 360hp and was a we bit bigger ! David

Mike, my point was that they are vertical not horizontal. I agree that 'opposed piston' differentiates them from the type of engine in an original Volkswagen Beetle but I can't think of a vertical engine with a single crankshaft in the middle. For those that don't know the other engines mentioned, the Routes TS3 had three horizontal cylinders with opposed pistons each connected by two connecting rods and a pivoted lever to a single crankshaft below the cylinders. Amazing sounding engines. The Deltic engine had three crankshafts in a triangle with three cylinders between them each containing two opposed pistons. I don't remember how many cylinders 'long' the engine was but it produced vast amounts of power when it worked - typically British ! David

I think it must be lying on its side and is actually a K60 (FV430 family) or L60 (Chieftain family) which are vertically opposed engines. The two crankshafts are geared together down one end of the engine. They are slightly out of phase with one set of pistons controlling the exhaust ports and the other set the inlet ports so it is rather more efficient than a conventional two stroke but has no cylinder head or gasket or valves. A very clever piece of design and pretty reliable once they gave up the multifuel requirement. L60s in particular were dreadful up to that point and at 104 hours it could well be toast ! David

I like the left hand fitting on the radiator top tank. Those 3D printed details are very nice. David

No, not bored but very impressed with your stamina and commitment. I think that most people would have regarded it as not worth saving. Most of these cabs were rotted out 40 years ago which is why these trucks are so rare now. David

It certainly look like the bell housing can be LH & RH drive. At least that is easy to confirm by looking under a car. However the steering box does seem to be handed judging by your photos. David

When I was a student I commuted 120 miles each way every weekend and it was my daily driver in between for two years. I ran with the ignition considerably advanced on the official setting (but not to the point of pre-ignition) and got 16mpg routinely. The only problems that I had on the road were a baffle came loose in the non standard silencer which blocked the outlet and a master cylinder failure which was a bit exciting as I was going down a fairly steep hill with a T junction at the bottom with traffic lights. Luckily they went green at just the right moment ! The gearboxes have rather fragile synchromesh and I rebuilt my gearbox out of two when I first got it, fitting the best synchro rings in mine. They are bronze and several had broken up. I also reinforced the handbrake pivot on the seat base to stop it moving back and forwards when I applied the handbrake. Big improvement. Oil levels are critical and if it doesn't drop oil it is either fine or run out in which case some part of the transmission is dying. As mentioned above it was vastly better to drive than the S2 & 3 Land Rovers but you must remember that 65 is about the maximum speed and don't expect to stop quickly from that ! I really loved mine. David

OK guys, I give up ! Its not a Mack NO2 because of the wrong body and the front overhang is actually shorter than a DT 980. However I can't reconcile the very long bonnet of the DT with the quite short bonnet of the one in the photo. There is just not enough space between the cab and the front axle. As an aside, I clearly remember my local vehicle recovery company in Maidenhead, Leach and Jackson, taking delivery of an absolutely mint Mack NO2 in about 1969. As a schoolboy of about 15 I was most impressed by its sheer presence. They also got a very nice Matador at about the same time which I think replaced a blue painted R100 that sat outside their scrapyard premises. David

Sorry but the R100 has a rear body that is integral with the cab and has a hard top that doesn't come off. The Guy is much too small to pull that load. I still think that it is a Mack NO2. This would be so much easier with a clear photo but then we would miss out on the debate. David

The whole point of pressurized systems is that the higher the pressure, the higher the boiling point. That is why opening the radiator cap when the engine is hot produces an eruption of boiling water as the pressure drops. Just because the truck has an overflow doesn't mean that it's not pressurized. It depends on the design of the cap - does it have a spring loaded disk that seats in the filler neck just below where the overflow pipe joins ? I assume that you have tested the engine thermostat in a pan of properly boiling water to see that it works ? David

How about Mack NO2 as the tractor ? David

Looks to me that the Sherman has a bulldozer blade mounted and has been loaded backwards. David

It is Definitely a M26 Pershing ! Chaffies have 5 vs. 6 road wheels and completely different track. Shermans do not have torsion bar suspension or the outer edges of the belly at an angle or the double pronged guide horns to the track. M46 is very similar underneath but has the sprockets set higher in the hull. David

Yes Andy, I know that is how the switch should be wired but this one most definitely did have HT on it when running. It HURT ! I could never understand how it still ran but it wasn't my vehicle so I didn't feel it was my place to investigate. David

Is the 'mount' not just a piece of wood to insulate the switch from the scuttle ? I once drove a beautiful 1920s bus that had an old fashioned brass domestic round light switch as a magneto switch. It looked great but when the engine was running it had HT voltage on it which meant that you needed something insulating to turn it off . It started and ran great though despite this unusual feature. David

Hello Toni, Welcome to HMVF. I do not see these as sprockets. They are too simple and the 'teeth' have not been worn to that shape and would certainly not drive anything as they are too shallow. Also the bolt holes are too near the outside so what they were bolted to would interfere with the track. I see them as spacers, possibly between double wheels, or as a reinforcing disk between the wheel nuts and a wheel to prevent fatigue cracking of the wheel. They do look rather low- tech to be WW2 German, but I don't recognize them as either US or British armoured vehicle parts of that period either. Hopefully someone will make a suggestion. David

I think that the key to this is the rollers which must be in good condition or they will break up. However I think that the cams need only to be clean and not bumpy to give a good track for the rollers to roll on. A bit of pitting will not do any harm as long as the pits don't join up. I would set about the cams with abrasive paper by hand and just rub them until they are smooth. A slight change in profile simply won't matter on an engine as crude as this and as you say you won't be working it hard anyway. David

Great news, Good luck tomorrow ! David

Frans, Are you asking for the track tensioner 'snail' cam that tightens the track or the track 'jack' that pulls the ends together when you are fitting a track. This was actually a slightly modified car jack of the period but you can do the job with a ratchet strap used for holding the load on a truck. David

Well done ! Time to sit and admire it with a beer. David

I got very cross with RGM when I tried to buy something from them but we must remember that if these old traditional scrap yards had been more business like they would have cut these vehicles up fifty years ago. They own them and have no obligation to do anything with them. Many of these type of yards see these rotted remains as having been paid for so long ago as to be of no cost so they can just sit there and wait for some idiot with very deep pockets and no idea of reality. It is just very sad to see intact vehicles rotting away. David