Great War truck Posted January 4, 2009 Author Share Posted January 4, 2009 Here are some more photos of the box now in place. It was fun and games trying to get the holes lined up and we will still need to take the bolts out again so that we can put a tube around the outside of the bolts to strengthen the sub frame. At first we didnt think that we had the arm that engages the gear change, but on having a rummage around we found that we had an original one in grey primer that we must have taken off something and tidies up a long while ago. You forget what you have sometimes. Anyway, on putting it on we found that it engaged almost perfectly. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted January 4, 2009 Author Share Posted January 4, 2009 As you may probably remember we found the correct diff under a dismantled chassis on a Cornish beach. It had been sitting in our shed for a couple of years and as the gearbox was now finished this was the next big project. So on new years Eve we dragged it outside to have a look at it. The plan was to get it hot so that the bolts might release their grip, but as it was a bit chilly (-2.5) the gas in the bottle was not playing game, so we brought out a fan heater to warm up the gas cannister. Also as it was now dark a halogen lamp so we could see what we were doing. So we spent New Years outside in the cold and dark attacking a great lump of metal which was sometimes freezing and sometimes red hot. It was my best New Years ever. The first job was to get the end off. Thinking that it would never come off in one piece i was very suprised after a great amount of heat and with the help of a giant stilson it released all in good order. The bolts on the case were quite wasted, but Steve attacked them with a hammer and chisel and they all came away or unscrewed without too much bother. The balls in the race appeared to be in good order as well and had not been damaged by the gas. As you can see, a bit of sand has got into them so they will need a good clean. Quote Link to comment Share on other sites More sharing options...
N.O.S. Posted January 4, 2009 Share Posted January 4, 2009 It never ceases to amaze me when assemblies in this state of corrosion can reveal useable components when carefully dismantled, let alone be capable of almost total reclaim - this is the stuff that inspires me to work more carefully, well done guys! Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 4, 2009 Share Posted January 4, 2009 Tim, From the brief glimse of the bronze wheel it looks to be in good order. Hope the casing is OK. Great stuff, you are cracking on now! Quote Link to comment Share on other sites More sharing options...
Stormin Posted January 4, 2009 Share Posted January 4, 2009 Looking good! Get the diff restored and a propshaft installed and it'll be good for a test run. That should fire the entushiasm. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted January 4, 2009 Author Share Posted January 4, 2009 It never ceases to amaze me when assemblies in this state of corrosion can reveal useable components when carefully dismantled, let alone be capable of almost total reclaim - this is the stuff that inspires me to work more carefully, well done guys! You are quite right. It all seems to depend on how much oil was left in the part when it was finally abandoned. It was luck that this axle had turned and all the oil had gone to the top to cover the worm. It was also very lucky that the diff survived the lorrys dismantling to be used as the foundation for a chalet (but that might have been because the scrap man could not get it out). Very lucky that the guy demolishing the chalet thought that the chassis was worth saving and that the guy he told about it was interested enough and had no work on that day and had a truck big enough for it to fit on could collect it all on the same day that the site had to be cleared. We really only just managed to get this. All down to luck and the good grace of strangers. Luck sometimes is not always good. We just heard about another surviving subsidy Dennis with gearbox in place under another chalet - just a few days after it had been scrapped. Tim (too) Quote Link to comment Share on other sites More sharing options...
Great War truck Posted January 4, 2009 Author Share Posted January 4, 2009 Looking good!Get the diff restored and a propshaft installed and it'll be good for a test run. That should fire the entushiasm. That would do it! A bit more work to go yet. I must say that having three of us work on the Dennis keeps us motivated, however, the comments and enthusiasm from everyone on HMVF who reads this is a fantastic motivator, so many thanks everyone. Tim (too) Quote Link to comment Share on other sites More sharing options...
Great War truck Posted January 4, 2009 Author Share Posted January 4, 2009 Tim, From the brief glimse of the bronze wheel it looks to be in good order. Hope the casing is OK. Great stuff, you are cracking on now! It all looks quite good (although a little worn), however the worm is a little rusty at the ends. It does not seem to be on the part that runs on the wheel though so i think we can get away with it if we just tidy it up. With all these old trucks, they will never again carry the three ton load that they were designed for so we can probably get away with more than what they were designed for. Anyway, here are the final set of photos for this Christmas: Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 4, 2009 Share Posted January 4, 2009 With all these old trucks, they will never again carry the three ton load that they were designed for so we can probably get away with more than what they were designed for. Tim, With the better lubricants avaiable now as well. I would think the worm gear will polish up and as you say it is mostly rusty on the non-contact areas. :tup:: Quote Link to comment Share on other sites More sharing options...
Stormin Posted January 4, 2009 Share Posted January 4, 2009 Interesting assembly. I assume there are further planet gears inside the crown wheel to give differential action. Looks almost like a modern limited slip unit with the workings sealed. Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted January 4, 2009 Share Posted January 4, 2009 Interesting assembly. I assume there are further planet gears inside the crown wheel to give differential action.. Looking at my Dennis manual, the diff gears are neatly housed within the crown wheel. This type of drive is known as "worm and wheel", it was still used on some lorries through to the 1950's. Quote Link to comment Share on other sites More sharing options...
David Ives Posted January 4, 2009 Share Posted January 4, 2009 after reading this for the first time properly i am so impressed with the standerd of work that has been done when it is finished you will be the proudest people around like when the grandparents hold their grandchildren for the first time i wish i could do work like that but i was never any good at mechanical things and am just starting to learn now keep up the great work and comentry as will be following this with interst from now on Quote Link to comment Share on other sites More sharing options...
Old Bill Posted January 4, 2009 Share Posted January 4, 2009 Interesting assembly. I assume there are further planet gears inside the crown wheel to give differential action.Looks almost like a modern limited slip unit with the workings sealed. Hi Norman. Yes, the gears are inside. It is a spur gear diff rather than the more common bevel type so there are quite a few more gears inside. However, as they are straight cut, they are much easier to make. It will be interesting to see how much wear they have suffered. That will have to wait until the brake drum and shoes are sorted, however. One thing at a time! Steve Quote Link to comment Share on other sites More sharing options...
abn deuce Posted January 5, 2009 Share Posted January 5, 2009 Whats the condition of the clutch assemble or pieces you have gathered together so far ? Do you have a drive shaft or will that need to be custom made ? Quote Link to comment Share on other sites More sharing options...
Old Bill Posted January 5, 2009 Share Posted January 5, 2009 The fire pump engine had a complete clutch of a later type than the lorry so whilst some bits are common, some are not. We have some of the correct bits and could, probably, lash up something that will work. However, as we will have to make quite a few bits, we might as well make them to be correct for the vehicle and so that is the plan. The main clutch cone is in super condition and won't even need re-lining. Father has already made a new clutch release shaft and I have completed the clutch brake shoes and part of the release linkage. However, I am still not quite sure what we actually have so the next job for me will be to lay it all out on the ground and assess the job. We are fortunate that we have an original assembly drawing so I can draw up the bits from that and we can make them up between us. All good fun. Steve Quote Link to comment Share on other sites More sharing options...
abn deuce Posted January 6, 2009 Share Posted January 6, 2009 :tup:: Thank you for the reply Quote Link to comment Share on other sites More sharing options...
Great War truck Posted January 26, 2009 Author Share Posted January 26, 2009 I thought that you might be interested in seeing these photos of the transmission brake coming apart. All the bits totally rusted up and they were very diff to get apart. Usual extreme heat and thumping eventually did it but we found that the Hanger Pins were "mushroomed" at the ends following previous beatings and once we started to get them to move, they seized up again when the "mushroomed" head reached the hole in the casting. We had to cut off the end that we pushed out to get rid of the "mushroomed" bit and then were able to push them back the other way. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted January 26, 2009 Author Share Posted January 26, 2009 The Brake Drum was badly rusted and had to be skimmed to make it useable again. Rusting very deep in one part and badly pitted there (it had probably been sitting on the ground for 50 years). Father took off as much as he dared, but some of the pitting is still visible - although the surface to come into contact with the Brake Linings is now smooth. The Drum is 12" in diameter - and fully stretched our Colchester Student Lathe with its 6" centre height. Quote Link to comment Share on other sites More sharing options...
Stormin Posted January 26, 2009 Share Posted January 26, 2009 The Brake Drum was badly rusted and had to be skimmed to make it useable again. Rusting very deep in one part and badly pitted there (it had probably been sitting on the ground for 50 years). Father took off as much as he dared, but some of the pitting is still visible - although the surface to come into contact with the Brake Linings is now smooth. The Drum is 12" in diameter - and fully stretched our Colchester Student Lathe with its 6" centre height. Is that not a gap bed model of student with the travel handle on the right? Recently cleaned up some brake discs on mine and even though it'll spin 18 inches in the gap getting the tool to reach out there is awkward to say the least. Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted January 26, 2009 Share Posted January 26, 2009 You are completely right, Norman. As Tim said, the lathe was being stretched to its upmost to do this job and the tool was extended to its limit to reach the extremity of the drum surface. Not very comfortable - especially with the tool bouncing over the rusty pits and leaving some chatter marks. Tim has another three photos of the finished job to post which do show a better finish. Tony Quote Link to comment Share on other sites More sharing options...
Great War truck Posted January 26, 2009 Author Share Posted January 26, 2009 (edited) Yes, here they are: As you can see we have been left with the one very pitted place, but all the rest is acceptably smooth and the brake shoe very adequately covers it. If we take off any more then the drum will be too thin - and of course the difference in the radii of the shoes and drum will be getting even larger. Even now, there will be a fair bit of differentiation for the Linings to take up so we need to order up thick ones. Edited January 26, 2009 by Great War truck Quote Link to comment Share on other sites More sharing options...
abn deuce Posted January 27, 2009 Share Posted January 27, 2009 I have heard of people having shafts and other items that have been scored or damaged restored by a method called plasma spraying , applying new metal to a surface and then regrinding to return the object to original dimension could that be done to this clutch brake drum ? Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted January 27, 2009 Share Posted January 27, 2009 Steve is the best person to come back on this one and I expect that he will pick it up later on today. I know that "metal spraying" is an accepted process, but I do not know if it will work on this "dirty" cast iron without drilling or grinding out all the rusty bits first. Or even if you can do it on cast iron. My amateurish opinion is that there is now enough smooth metal there for the Brake Linings to be effective without tearing them up when being used. We have got rid of the really nasty corrosion on the Drum. Tony Quote Link to comment Share on other sites More sharing options...
sirhc Posted January 27, 2009 Share Posted January 27, 2009 I spend my days engineering thermal spray processes, both plasma and HVOF. We regularly repair worn and mis-machined parts for customers. As long as the part is properly prepared before coating then it should be possible to repair, even if there is pitting. Quote Link to comment Share on other sites More sharing options...
Old Bill Posted January 27, 2009 Share Posted January 27, 2009 Thanks for the suggestion. We did have metal spraying up our sleeves as a final solution but thought that a simple skim would sort it out well enough. I have only seen the photographs above but I think that although it appears a bit poxy there is enough shiny metal there to avoid any serious damage to the linings. After all, the normal service brake is the hand brake and the pedal operated transmission brake is always described as the 'emergency brake' in the manual, so it shouldn't get much use. Incidentally, does anyone know when the foot brake became the service brake and what instituted the change? Steve Quote Link to comment Share on other sites More sharing options...
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