Great War truck Posted August 4, 2009 Author Share Posted August 4, 2009 We got the diff back from the sand blaster today. Tony gave it a quick coat of primer, with another one to be done tomorrow. Looks better already. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted August 5, 2009 Author Share Posted August 5, 2009 Objective today was to get most of the sand and grease off the outside of the Worm Wheel so that the assembly can be stripped down. This shows the state of the wheel before we started to clean We knew that the wheel was very worn but hoped that there would be enough life left in it to fight another day. But as the sand and grease came off, it revealed that some of the teeth were not only badly worn, they were chipped and pitted. Food for thought here. Do we go for a new wheel at this stage whilst it is stripped down (costing about £1,000) or do we chance it? I think we will give it a go as it is and change it only if we have no alternative. The whole wheel looking much cleaner Quote Link to comment Share on other sites More sharing options...
Great War truck Posted August 5, 2009 Author Share Posted August 5, 2009 So to strip the assembly down, first thing to get the split pins out - take off the nuts and knock the bolts through with a mallet. Surprise surprise - but should have thought of it! All comes apart easily, but wheel full of oil and no prior provision made to catch it as it ran out. A real mess to clear up! here we have the inside of the wheel and the inside of the "lid" and here the splines for the half shaft - I hope that they clean up OK and are useable. Quote Link to comment Share on other sites More sharing options...
Great War truck Posted August 7, 2009 Author Share Posted August 7, 2009 Minesweeper paraffin washed the diff components today - a mucky job but all done OK. There is some rust around the splines for half shaft but this is not too deep and we are quite sure that they will be OK when the rust is removed. A wire brush job! These four pictures show the worm wheel still attached to the other "cover" after cleaning. Mysterious markings engraved on the bronze! Quote Link to comment Share on other sites More sharing options...
Grasshopper Posted August 7, 2009 Share Posted August 7, 2009 Thanks for keeping us all updated with this thread, i find it inspiring. Doing my Scorpion project it helps knowing that there are bigger, more difficult projects being undertaken! Vince Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted August 8, 2009 Share Posted August 8, 2009 Steve tells me that the stamped numbers on the Bronze Wheel are the drive ratio and the pressure angle of the gear. That is sufficient information for the pair to be remade if needs be. We are very fortunate to have this. Quote Link to comment Share on other sites More sharing options...
Swill1952xs Posted August 8, 2009 Share Posted August 8, 2009 What would have caused the pitting on the crown wheel teeth? Could it be due to poor lubricant quality.... or lack of it? Apart from wear grooves in the teeth of the crown wheel, it must be difficult to judge the exact amount of wear; as the teeth never quite appear to be the shape you would expect them to be...... ie, having a flat top to the teeth, rather than the apparent sharp edge. It's a whole different piece of kit from a spiral bevel gearset. Doesn't look like it went round too many corners though. The diff planetary gears look to be virtually new. One final question regarding the diff outer casing. Will you be leaving the casting in the form it is at the moment, or will you "Dress" it in some way to reduce the pitting. Rust pitting must be an annoying problem when doing a restoration to the standard of the rest of your truck? Quote Link to comment Share on other sites More sharing options...
Old Bill Posted August 8, 2009 Share Posted August 8, 2009 The cause of the pitting is rather guesswork on our part. It could be corrosion due to suphur compounds in the oil. EP oils have these and they eat bronze so it could be that although I don't know when EP oils came in. The lorry probably went out of service before they were invented! Dad hasn't mentioned whether the pitting is on all the teeth or just a few. If just a few, they could be the ones left in the oil after the lorry was laid up and they corroded then. The other possible reason could be lumps dropping out of the surface due to fatigue in the same way that rolling bearings spall after extended use. This wheel is in a high surface pressure application and although the number of loading cycles on each tooth is nothing like that seen in a bearing, the bronze is a lot softer than the alloy bearing steels. I'm sorry, I'm guessing! Is there a tame tribologist out there please? We won't do anything about the pitting of the casing as it is ninety years old and we don't mind if it looks it. However, the front bolting flange locates the torque tube so we will have it skimmed just enough to give a solid mounting. Our target restoration standard is to put the vehicle into good working order, looking its age but also looking as if it has been loved and maintained with factory parts. Cheers! Steve Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted August 8, 2009 Share Posted August 8, 2009 The pitting is not on all the teeth - say bout 30% of them - and scattered around the circumference in no regular pattern or groups. Tony Quote Link to comment Share on other sites More sharing options...
Enigma Posted August 13, 2009 Share Posted August 13, 2009 Great project. I think pitting is OK, it gives a idea of the work that had to be done. Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted August 17, 2009 Share Posted August 17, 2009 Tony has had a go at cleaning the rust out of the two "Differential wheels" inside the Differential assembly. The splines in both wheels were quite heavily rusted as they were not protected from the elements when the chassis was put aside all those years ago This shows the splines before any work done on them. The splines after chipping, wire brushing and scraping. A trial fitting on the end of the half shaft (another challenge approaching there as we only have one half shaft! The one that we have is very deeply pitted along its length so it may well be that we will have to make two as the oil seal - leather - runs on the half shaft and will never seal on it in its existing condition). Obviously the Differentail wheels do not look pristine, but they are going to be a good snug fit on the half shafts so I am keeping my fingers crossed on that one! Quote Link to comment Share on other sites More sharing options...
chevpol Posted August 17, 2009 Share Posted August 17, 2009 wow!!! Mark Quote Link to comment Share on other sites More sharing options...
Stormin Posted August 18, 2009 Share Posted August 18, 2009 A trial fitting on the end of the half shaft (another challenge approaching there as we only have one half shaft! The one that we have is very deeply pitted along its length so it may well be that we will have to make two as the oil seal - leather - runs on the half shaft and will never seal on it in its existing condition). Haven't seen the half shaft yet, but any chance of using a speedi-sleeve over the part of the shaft where the seal runs? Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted August 18, 2009 Share Posted August 18, 2009 Steve has had a go at filling the indentations in the half shaft around where the seal will sit and this may work. I'll leave it to him to post details of what exactly he has done - probably later on today - but I will post a picture of the half-shaft later as that will help explain - and you will be able to see it for yourself! Tony Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted August 18, 2009 Share Posted August 18, 2009 Here are some pictures of the half shaft: Here is the inside of the axle casing showing where the oil seal retaining assembly goes. Quote Link to comment Share on other sites More sharing options...
Old Bill Posted August 18, 2009 Share Posted August 18, 2009 This is the half-shaft seal before we removed it from the axle. It is a simple leather lip-seal held in place with a washer and clamp screws, suitably wire-locked as one coming loose and going through the gears is not to be countenanced! This half-shaft was left in one of the recovered chassis. The chassis had obviously not moved for a very long time as the shaft is deeply pitted all along one side. The seal runs on the surface so I repaired that with titanium loaded Devcon filler which sets very hard indeed. I dressed it back and polished it and the surface is pretty good now so I think we will get away with it. We now need another half-shaft which would be simple enough to make but is just a bit big for my equipment. I might have a go but we shall see. Of course, we need to make new seals as well. I don't know much about leather but I understand that if one soaks it in water for a number of hours and then just works it into shape over a mandrel then it can be left to dry and will retain that shape. One fully dried, I will dress it with oil and install it. That is the plan, anyway! Steve Quote Link to comment Share on other sites More sharing options...
Richard Farrant Posted August 18, 2009 Share Posted August 18, 2009 Of course, we need to make new seals as well. I don't know much about leather but I understand that if one soaks it in water for a number of hours and then just works it into shape over a mandrel then it can be left to dry and will retain that shape. One fully dried, I will dress it with oil and install it. That is the plan, anyway! Steve, I have successfully made leather piston seals for Clayton servos with the method you describe. Quote Link to comment Share on other sites More sharing options...
Old Bill Posted August 18, 2009 Share Posted August 18, 2009 Oh good! I will let you know how we get on in a week or two. Steve Quote Link to comment Share on other sites More sharing options...
andreadavide Posted August 19, 2009 Share Posted August 19, 2009 Besides, some oil leak should be tolerated. It's a British vehicle, after all! 8-) Andrea Quote Link to comment Share on other sites More sharing options...
CommanderChuff Posted August 20, 2009 Share Posted August 20, 2009 Tony has been very busy working on the diff so i have lots of photos to post for you. I do hope we are not boring you with the minute detail of this project. As a interested party in this epic and a non vehicle owner I am fascinated by the progress of this restoration. The detail of the vehicle is interesting for the technology that the makers had available and the solutions which were employed to overcome practical problems. Please do continue with recording the historical record of this excellent project which is a credit to you and the team, and an inspiration for the rest of us. David (modeler of Montgomery's British Army in Overlord) Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted August 20, 2009 Share Posted August 20, 2009 (edited) Many thanks for everybodys positive comments (and yes, you are quite right about the oil situation, Andrea). We are amazed that this blog seems to attract so much interest and that the number of hits keeps leaping upwards. I notice that the number of hits seems to jump up between about 11:30PM and 6:30AM,BST, so I assume that there are a number of interested people in different time zones. With comparatively few surviving MV's coming from the WW1 period I am delighted that people keep reading this and offer such enthusiastic replies and advice. I think that the "basic technology" of WW1 trucks makes it very easy for the layman to understand especially when you see it all broken down into hundreds of photos. We can tackle this level of restoration as we can do most of the work ourselves, but we would probably be unable to do the more complicated modern stuff that you lot do (anything from about 1930 onwards is modern to us). If nothing else, I do hope that this restoration thread gives some advice or encouragement to others who might consider the restoration of a similar age vehicle. Thank you everyone for all your support and your useful comments. Oh yes and before I forget, we are still considering what to do about the half shafts. Tim (too) Edited August 20, 2009 by Minesweeper Quote Link to comment Share on other sites More sharing options...
Charawacky Posted August 20, 2009 Share Posted August 20, 2009 The Dennis Half Shafts are interesting in that the spline cutter has been withdrawn to give a taper rather than a stress point. Interestingly a 3 litre Bentley (standard 80hp) half shaft has a 90 deg stress raiser where an end mill cutter has been lifted vertically and an 8 litre (standard 220hp) has an identical half shaft but the mill cutter has been with drawn to create the same taper as the Dennis half shaft. Just goes to show how engineers sometimes learn the same thing over again. Quote Link to comment Share on other sites More sharing options...
Jack Posted August 20, 2009 Share Posted August 20, 2009 Just keep up the good work guys - it is fast becoming a very historic record that may be around for hundreds of years, spooky thought that. Quote Link to comment Share on other sites More sharing options...
Old Bill Posted August 21, 2009 Share Posted August 21, 2009 The Dennis Half Shafts are interesting in that the spline cutter has been withdrawn to give a taper rather than a stress point.QUOTE] That's interesting. I had always thought that the run-out was caused by the radius of the tool as I had assumed that the slots were cut using a horizontal milling machine. Whichever way they were made, that run-out is much better than the square end that would be caused by a vertical milling cutter being lifted straight out. Does anyone have any suggestions for the material for the shafts? I don't think they are anything exotic and planned to use the equivalent of EN8 or EN24. ( Why do we all know exactly what EN numbers mean when they have been obsolete for forty years?!) Cheers! Steve Quote Link to comment Share on other sites More sharing options...
Minesweeper Posted August 21, 2009 Share Posted August 21, 2009 The differential case has now been painted and all new studs made and fitted. We will give the paint a few days to harden off and then give the case a final internal clean with fresh paraffin. Then we can start to put it all back together again. Tim (too) Quote Link to comment Share on other sites More sharing options...
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