David Herbert

With rubber bushed track like CVRT or FV432 it is possible for the rubber bushes to fail. When they do they deteriorate very quickly and the whole hinge between adjoining links goes metal to metal and eventually you get wear between the pin and the actual link. As a result that pair of links go over pitch and won't run smoothly over the sprocket. You can easily spot dead bushes by looking at the inside face of the track (where the wheels run) and compare the gaps between each link and the next. If bushes have failed the gap will be 1/4" or more bigger than normal. If you have a few gone it makes a real difference to track tension and is really not very safe at more than walking speed. Obviously if you are going to remove a link, first check that the bushes are all ok on the rest of the track. Move the vehicle so the link you want to remove is under the sprocket and break the track there. This allows you to use the parking brake to keet the tension on the top run of the track giving the track clamp an easier time. With a CVRT it is possible to pull the ends of the track together with a ratchet strap but the proper track clamp is much better. Similarly the correct tools for removing and replacing the pin make life easier and save damage to pins. The reasion that track should be condemed if 15 links have been replaced is only that if that many have needed replacement the rest are not long for this world. More important is that you don't go below the minimum number of links allowed, and that you have exactly the same number on each side of the vehicle. Have fun, David

I am sorry to say that most museums see themselves as the only proper custodians of historic objects and actually selling unwanted items to mear enthusiasts as a form of prostitution. After all we might sell them on and make more than we gave them (obviously the cost of restoration doesn't count !) or actually play with them. From their perspective we are just a bunch of hooligans who should butt out and leave history to them. Please don't think that I have strong views on this but the above is a paraphrase of what I have actually been told on more than one occasion by employees of two significant museums in our field. To be fair to the Batterie Todt museum the tank was in a dreadfull condition. It had been in the sea for a very long time and the salt had got into the structure of the metal. As soon as it got into the open air it just started crumbling away and parts that had looked quite good initially turned to flakey rust. Even I had to admit that it couldn't be saved but why couldn't it have been offered to the open market ? If anyone has seen the SS Great Britain on display in Bristol, that was refloated as part of its recovery from the Falkland Islands but now has hundreds of significant holes that wern't there when it got back to the UK. They got very concerned and finnished up making a glass 'sea' surface at the water line so they could have a very big dehumidifier keep the humidity down to a very low level both outside and inside the lower part of the ship. This has helped but it is an ongoing problem. If you are in Bristol I thoroughly recommend a visit. David

If there is no phase change, how does the annealing change the aluminium ? Sorry to be thick ! David

Had the truck been used to deliver live fish? David

I like your hinge making tools. A few comments that I am sure you already thought of or would do by yourself ! On the first opp. tool you could radius the edges of the hole and lightly lubricate them to ease the movement of the brass over them. Also a stop to position each brass blank in exactly the same place - then there would be no need to start the bend as a seperate opp. and they should be more uniform. On the seccond opp. tool you may need to clamp the long leg of the brass to the tool to stop the 'U' being pulled around the pin as you press the short leg. Practicing with bits of scrap should get the right bending allowance in three goes or two if you are very good. First go would just be flash ! You might find that the spring back of the brass is enough to need a rather smaller pin than the final hinge pin diameter. Good luck and I look forward to seeing how it works out. David

I had never thought about it before but looking at Lauren's picture makes me think that the breach end of the 3" howitzer couldn't have left much room in the hull gunner's position for a hull gunner. Did they even have a crew member beside the driver or did the turret crew man the howitzer? Presumably the amunition was stowed in the sponson next to the gun ? David

I think that the problems that people have with cast aluminium radiator tanks are mostly caused by a combination of the deeply horrible grade of aluminium that the originals were cast in and the fact that for a good part of 100 years they have not seen coolant with corrosion inhibitor in it. If you are making new tanks I think the choice of cast / fabricated is more about appearance, convenience and practicality. Many WW1 top tanks would be hard to fabricate convincingly because the cast in maker's name or ribs on the front face are just too hard to reprisent. On the other hand bottom tanks tend to be rather simpler and more rectangular which would make it easier. With either method you can make flanges etc. thicker quite easily. You could even have a cast piece welded into an otherwise fabricated tank. The Vulcan top tank lends itself to fabrication because the areas of double curvature are relatively limited and all of the original visible outer surface was polished. If the original was left as cast it would be hard to reprisent that after fabrication, though blasting with course grit goes some way to rough it up. It all depends how complex a shape it must be. It is much easier carving a pattern to shape in wood, with a bit of filler, than it is to get the same shape flawlessly in polished aluminium. That is why the Vulcan tank is so impressive and the originals were cast ! David

I will definately just watch from here ! David

Solution is more bank holidays David

So possibly only 14,400 for the one radiator, that is much better ! Mind you, they still have to be individualy threaded onto the tubes, presumably all the same way up. That would keep you out of trouble for a while. I think I will just watch from here . David

Yes Andy, just what I was thinking ! Actually 20,000 does sound an awfull lot, is that really the right number ? David

That is VERY nice :thumbsup: David

I think the mug of tea is to balance the load . These cranes have never had the following that they deserve. It is great that you are throwing so much enthusiasm into it and that you have such a good excuse to use it. They really are quite good cranes if used properly. David

We (The Brits) did ask the Canadians to build us Crusaders which at the time were the latest thing. When they got the drawings they were very unimpressed and the final compromise was the 'Medium Tank M3 (Canadian)' which became the Ram, sometimes designated 'Medium Tank M4 A5'. David

I have just been told that Daimler ACs have an Episcope No6 Mk1 and a couple of Periscope No1 Mk1s. David

Barrie, Yes, DAS = Duxford Aviation Society LWH = Land Warfare Hall at Duxford I think you did well to guess the first one ! David

Hi Clive, I did wonder about the "Pin Head" style trakmark but I didn't think of the posibility of the MOD panic buying any remaining stock. It is certainly possible but the fine pattern material is a slightly lighter, less rich colour than 'real' trakmark which might suggest a different manufacturer. There was also a very unpleasant green colour that was used on 432s as the original diamond pattern became unobtainable. This seems to have been supplied already glued to its foam as there were no covered edges, it had obviously just been cut out of big sheets and glued straight to the vehicle. Andy, It could be that "normally applied as a two coat system" means that it took two coats of the silver to get coverage rather than that it must have a primer. As it was supposed to be fire resisting they seem to have cut down on the laquer content which is why it rubs off so badly and that would also have made it harder to get a decent coat without it running. David

So the Trakmark is reasionably fire resistant but not the foam - great ! I used to have my business next to a guy who made bench seating for pubs. The foam he used was not in itself fire resistant but he had a water based thin liquid that he sprayed onto the foam after it had been cut to shape but before fixing. The amount needed was quite small, definately not soaking wet. The foam pads would be allowed to dry overnight and would be ready to use the following day. If you directed a blowlamp at it it would grudgingly burn but it was impossible to get it to burn by itself. One wonders why the MOD couldn't have done the same ? I have a FV434 that was rebuilt at Bovy in 2002. As you probably know the standard beige diamond pattern Trakmark became obsolete in about 2000 and my 434 is entirely padded with the much finer pattern material that superceded it. Does anyone know what this is called and where it comes from ? On first sight it has a matt finnish but it is actually a very fine, regular, pattern of dots. It goes hard, discolours and curls up just like trakmark and most of mine would benifit from replacement. I have trawled the web but to no result. David

Sorry Lauren, I rather lost the will to live going through a lot of parts lists looking for periscope info. That said I am suprised that I didn't note down what the episcopes fitted as I could easily have done when I copied the drawings. David

Rick, I don't think that water resistance was very high on the agenda with these periscopes. You are quite right that the armored shrouds have thicker bases on the later designs but I have not noticed any significant differences within each design (for example No.1 Mk.1). In fact some cast turrets actually have the periscope sitting in a depression in the top of the turret which collects water that then runs into the turret past the prisms. Realy not very clever. My reference to episcopes being non rotating periscopes was refering to those terms as used in official parts lists. I think that most people now would describe both (and also the "protectoscope" indirect vision device) as periscopes. To confuse it further, the vision devices used in the rotating comander's cupolas were refered to as episcopes in WW2 but as periscopes in post war British vehicles such as FV432s despite doing exactly the same job. David

Thanks to Eddy for airing my attempt to compare the different British periscopes. They were often refered to as "Vickers" type in official publications. I should stress that there are probably other variations but I went through nearly all British AFV parts lists from Covenantor to Comet and tried to copy the best drawings of each different version, and to record what they fitted and the differences. Note that the handles and rain hoods are mostly interchangeable so can pop up almost randomly, though there was an official 'correct' set up for each position of every vehicle. Also many earlier vehicles that originaly had No.1 periscopes had them replaced by No.6 which became the standard (ish) WW2 periscope. Also the rain hoods came in many versions, in both steel and brass and with so many detail differences that I think they must have been contracted out to small companies who were allowed to vary the design as long as it still worked. An interesting variation was that when Canada started making Valentines, they made their own periscopes, including their version of the No.3 Mk.I . This was inherited by the Ram, and then made 3" taller for use in the turret, like the No.1 Mk.II used in Churchills (driver & hull gunner). As Eddy has mentioned, the Russians copied and then improved the No.1 Mk.1 and used them in many AFVs including T55 (gunner) and MT-LBu (co driver). These ones have propper seals to keep the weather out, ours never did. Note that a No.5 episcope (for example) is not directly related to a No.5 periscope - it is just the 5th major version. Also an episcope is a NON rotating periscope, though both can move in elevation usually. I hope this is not too mind numbing.... David

Surely those are the return springs for the brakes (dual system- parking and service) you can follow the linkage up past the gearbox. David

It is indeed a Comet, modified as a mobile target. I have seen at least one on a range somewhere but can't now remember where. Another one sat outside a TA centre and I believe went into preservation. There was a much more heavily up-armoured conversion done of the Centurion in a similar style. Several of them were put out on the Warminster side of SPTA when Centurions were declaired obsolete after the first Gulf war. David

You have certainly made good use of the Christmas break - what a difference ! Well done the Goslings ! It may well be that Thornycroft had other ideas but I was 'brought up' to always put bolts in from the top so that if the nut were to come undone, at least the bolt would probably remain. It is also marginally easier as the bolt doesn't need holding up while you put the nut on. Obviously it is easier to split pin it with the nut at the top and the nut is then unlikely to undo by itself but I still find nuts on top just feels wrong. What does everyone else think ? This post was prompted by the thought that the steering box would have been nearer to fitting if the engine mounting bolt had been fitted from the top. Then I wondered if 1/4" packing plates under the feet of the steering box bracket would solve the problem without any noticable change to anything else and would be virtually undetectable when the vehicle is complete. Happy new year to everyone, David

Well spotted - I missed that. It's a Loyd carrier ! Very desirable in almost any condition. David