David Herbert

Not sure that I understand the question properly but as I see it the 'tab' is there to prevent a clear path for splash when the gun is at full elivation and the bottom edge of the mantlet would otherwise be higher than the bottom edge of the opening in the turret front, or too near to being clear. It also has the effect of stiffening the mantlet which is weakened by the hole for the main gun. David

We all are !

Count me in ! David

Very good point Ian David

64EK26, I thought that might be the case. I suppose it is possible that a LED equivalent might be a bit shorter and of course there would be no question of it getting too hot. David

Ron, If a standard 6 / 21 W bulb would fit in the housing you would have to file one of the pins off it or modify the holder as the 6/21s have the pins at different heights to make you put them in the right way round. With a 6/6 W it doesn't matter so the pins are the same as a single 6W David

Those look nice, very much like one of the WW2 patterns. I think that the bead as shown in the photo is narrow enough that it won't matter what angle it is at but the diameter will be critical. There is a debate about this in the recent ongoing thread about Trak-grip tyre re-manufacturing. David

64EK26 No, that lamp is marked B-WD-T which stands for : Butler = the manufacturer WD = War Department T = Tail I do not think that those double fillament bulbs are still available but happy to be proved wrong. Note that both stop and tail are 6w and the bulb can be inserted either way round as the pins are the same difference from the tip and it makes no difference. David

Thanks Richard, Frightening that one can make assumptions based on too little evidence. I suppose that I assumed that the pieces that I actually took off were identical to the many that I didn't and as they look the same when covered in paint, that there was no difference. Nice to learn somethng David

Pyramid nosing is new to me too. I have always called it 'grip strip' or 'that strip with lots of little bumps' ! The stuff that Mark has is solid rolled strip with the pattern rolled into the top surface and flat on the other side. The WW2 version is rolled out of much thinner sheet metal with the pyramids pushed up from underneath and a flange down both edges for stiffness. I strongly suspect that this lightweight version was a WW2 austerity measure and that the WW1 version was solid like the current stuff. Does anyone have an example that is definitely WW1 that they could check ? It actually makes little difference as you have to look very hard to see which it is once fitted and painted. Isn't the forum great that within about an hour of Steve menioning that he needed it, someone had offered a piece and delivery over about 200 miles was organised. David

Sorry Mark, didn't realise it was you ! I don't know which day yet but could you PM me a phone number and we can talk about it. David

Mark, where are you ? I am traveling down to Dorset (where the truck is) next week and could possibly pick it up from you as I expect to be going via Hull so will be going down the A1. David

Hopefully the engine has freed up now it is cold again. If not there is the possibility that something has 'picked up' which would be depressing. It would be worth checking that the oil is still clear. There is no way that you could finish the wearing surfaces as finely as a modern production line so it is bound to need a lot of running in. But well done for getting this far. David

Steve, I can't find valve timing details that directly compare to the Thornycroft engine but I could easily believe that the figures that you quote above are correct. A more modern engine would have more inlet opening both before and after but certainly not 12 degrees earlier unless it is supercharged. Similarly you don't see much later exhaust closing on older engines. Engines that I have worked on with wrong valve timing (admitedly with a single camshaft) just run badly, they don't idle well but refuse to rev up and die. I think it is carburettor ! At least it goes. I would want to put it in gear and see it move for the first time in many many years. Well done for getting this far without a heart atack. David

I missed the original post. Yes, looks very painfull and at least 3 months out of his life with no manual work possible. It is very easy to have a narrow escape, laugh about it and not learn untill you are not quite quick enough. I am puzzled that he seems to have two left hands with different damage though ! David

You might want to consider that the Trac-Grip name was a design that evolved over time. In fact the first ones (in the 30's I think) were just continuous bars that went all the way from one side of the tyre to the other with no link to the next bar. They were slightly S shaped and at a slight angle which presumably made them a bit quieter. Then they changed to the general design we know but kept varying the shape of the shoulder. Some have the extension of each bar hollowed out where it is on the side of the tyre. Some have a little bite out of alternate bars at the shoulder and alternate bars longer than the ones between them. Later tyres have plain, solid extensions to the bars on the sidewall and relatively square shoulders, which gave way to more rounded shoulders. Eventually some larger sizes had gaps in the bars about 1/3 of the way from the middle of the tyre, I think to give more even wear. Once you start looking for these differences on period photos, they are easy to see so I won't post pictures here but no doubt everyone will have different preferences ! David

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Not all the AT series were one particular type of vehicle and the numbers were allocated in blocks with some numbers and blocks not used but your number is the 4919 th number in the AT series. It should also be on the rear of the vehicle and be stamped on the data plate inside. There will also be a hull number (like the chassis number on a civi vehicle) stamped into the hull but CVRTs are not my subject so can't tell you where. David

No idea from the part number but it looks like the differential from a small traction engine or a road roller. The brass bush turns freely on the rear axle and the big spur gear that drives it bolts to the outside flange. One big bevel gear is keyed to the axle and that takes the drive to the wheel on the far side of the machine. The other big bevel gear is fixed to the inside of the other wheel and that is free to rotate on the axle. The four holes are there to take a pin that can be inserted through a hole in the wheel that is against the differential. That locks the wheel to the differential assy thus locking the differential. David

I think you might find some to play in tomorrow night ! I had a little play but it is surprising how much snow gets on the seat when you hop out to take a photo.

No idea either about the EMER either but this can not be a matter of adjusting anything as that would require it to be wrongly adjusted when it had been ok. How could that happen ? I understand that this problem started suddenly, nor over a long period so it is something broken, blocked, or stuck. David

Mine will cold start quite easily at minus 2 degrees C (at least it did a couple of weeks ago) as long as the battery is good. Smokes a bit more but not too much cranking. You say that it won't idle when it is cold. Obviously it is a matter of degree but they never do. That is why you have a hand throttle. I usually start mine with about half throttle and then release it when it starts to rev. There is no automatic compensation for cold starting/running. It is up to you to use the throttle to get it to go. Result is lots of smoke and noise - GREAT ! David PS Just thought: There is an engine switch panel for the crane opperator just inside his hatch. I doubt that it is possible but might be worth checking that the switches move easily and are not stopping the engine in spite of the driver's switch.

It is very unlikely that the injectors are defective. Compared to a truck engine they simply do not get enough hours use to wear out. Can I suggest that you loosen one of the high pressure injector pipes, just a little, and see if there is actually any pressure when trying to start. I suspect there will be almost nothing, which leads back to the FIP solenoid and mechanism. Are you sure that the solenoid is pulling all the way when the starter motor is cranking ? There is much less voltage then which is why there are two coils in it. Don't try resetting adjustments that worked ok before your problem started unless you are sure that they have come loose and changed themselves. David

Hi Glenn Sounds like fuel supply is ok. As I said there are two coils in the FIP solenoid. One powerfull one that operates on the reduced voltage available during cranking. The other weaker one to maintain it once the engine has started. If only the seccond coil is working the engine will not start but will run if you start it on a spray can. The 'off' position on the switch just cuts power to these coils and a small amount of stickyness in the mechanism will stop the rack returning to the stop position so the engine keeps running untill you press the pedal which has much more force available. You cannot just use a stronger return spring on the rack as the solenoid has to be able to overcome it with its limited pulling power. I think you have two problems here: A generaly sticky mechanism preventing it from stopping and a non operational coil in the FIP solenoid (this could be damaged wiring). No need to invest in a whole FIP yet. The rest of the FIP is very unlikely to ever give trouble though obviously anything is possible. Can I suggest that you put your location into your user profile, then we can see if we can come and help you personally or if it is worth suggesting sources etc that might be on the other side of the world. David PS. What is your army registration number and hull number (on a very small plate welded above the rear registration number plate). Mine is 02 FA 23, Hull 322 (for some reason the '3' is upside down!)

When you say you suspect the fuel pump do you mean the electric one in the tank or the injection pump on the side of the engine beside the driver? Both are actually remarkably reliable but..... There is a filter on the intake to the electric pump. To get to it you must drain the fuel tank (up to 460L) and remove the pump and filter through the access panel under the crane operator's step. It is very common to find the filter blocked with black gunge which can be cleaned off with some effort and the filter reused. This is not exactly a fun job so before you do it, it is worth checking the element in the filter on the engine and before replacing it (best with a new one) run the electric pump and see how much fuel is delivered (catching it in a suitable container).There should be quite a lot. If you think the fuel is getting to the fuel injection pump then the most common fault there is that the rack sticks. Usually you notice this because the engine won't stop from the switch on the switch panel and has to be stopped with the red emergency stop pedal in front of the steering levers. Sometimes this doesn't return easily and the engine won't start. Also the electric engine stop that is controlled by the 'ignition' switch is a solenoid that can itself seize up. It has two wires controlling it. One is powered up during the start and the other maintains it in the run position once the engine is running. Luckily this solenoid is easy to get to and test. Unfortunately there are not many spare ones to be found. If the rack is sticking it is usually possible to free it with a lot of waggling and WD40. There is a video of the FIP solenoid working on YouTube which shows why you shouldn't play with the switch and have your finger in the mechanism at the same time - it is quite powerfull ! It will be worth you joining the FV432 forum. In the FV434 section there is an excelent thread on how to remove the fuel tank if you have to, and lots about what I have mentioned above. All the important manuals can be downloaded there for free. I expect you know but it is critical that you keep the govenor oil topped up. Use red auto transmisson oil (Dextron). The actual transmisson uses ISO30 engine oil (as does all the rest of the vehicle except the final drives next to the sprockets). If the govenor runs out of oil the engine will go to full throttle and destroy itself very quickly which is not good ! I hope some of this helps David