WW1 Dennis truck find

Several people have asked us how we got into the hobby with World War One trucks. If anyone is sufficiently interested to read it, Mark Barnes did one of his "Interviews" with us a year or two ago under the title "An interview with Great War Truck and his family". You can find it by clicking on

http://www.hmvf.co.uk/index.php?option=com_content&view=article&id=102:great-war-truck-tim-gosling-a-family-by-mark-barnes&catid=24:interviews&Itemid=26

We should have some more photos of the Dennis restoration posted up soon.

Several people have asked us how we got into the hobby with World War One trucks. If anyone is sufficiently interested to read it, Mark Barnes did one of his "Interviews" with us a year or two ago under the title "An interview with Great War Truck and his family". You can find it by clicking on

 

http://www.hmvf.co.uk/index.php?option=com_content&view=article&id=102:great-war-truck-tim-gosling-a-family-by-mark-barnes&catid=24:interviews&Itemid=26

 

We should have some more photos of the Dennis restoration posted up soon.

Post copied over to original thread http://www.hmvf.co.uk/forumvb/showthread.php?t=3657

The Torque Mounting Flange on the Diff case was heavily corroded and although the rust was removed when sand blasted, it left the face quite pitted and uneven. As this joint is highly stressed when in service, we were concerned that the surfaces would not meet closely enough to prevent the flanges from cracking. We have therefore, arranged for a friend with a large horizontal milling machine to skim the face flat.

As the back axle is connected to the chassis by a torque tube, there is no universal joint between the propellor shaft and the differential. The connection is made by a piece of thick tube with an internal spline.

We described earlier that we were going to be faced with replacing this as it had been exposed to the elements and there has been significant corrosion.

We decided to make the "blank" ourselves and have the splines cut by wire erosion - a special form of spark erosion.

A 80mm piece of EN8 has been turned down to to 2 7/8" diameter, a 1" hole has been put right through it to allow the wire to be fed through, and one end has been counterbored for lubrication purposes. This blank will now got to the Specialist to be completed.

Tim (too)

We mentioned earlier that the new splined coupling was to be made by wire erosion - Steve prepared a drawing of the spline by measuring the spline on the worm and this was handed to the EDM Wirecutter Specialist.

This was satisfactory for his purpose and he has firstly prepared a template which he has cut in 5/16" Gauge Plate for us to test on the spline. This has only arrived today and a first attempt to slip it onto the spline has failed as it is very tight. The actual coupling will not be cut until we are satisfied that it will fit.

It appears that the spline on the worm is not as clean as we thought that it was and that there is still some dirt and rust in the corners to be removed. Then it will be tried again.

The quality of this wire erosion is remarkable and the cleanness of the cutting is very apparent in the photo.

IMO The accuracy of present day manufacturing be it lazer,waterjet,plasma or wire erosion could not been dreamt of back at the start of 1900 .

Quite true, but isnt it truly amazing what they could achieve with the basic tools that they had then?

Following a clean up of the splines the gauge fitted rather well:

So we have gone ahead with the manufacture of the actual coupling by wire erosion. It is being done even as i write this and should be finished by tomorrow morning. Looking forwards to seeing it when it is finished. Here is the blank in the machine.

another great solution to the missing parts problem . likely it will be better and stronger than any original you would ever find any how .

The finished coupling and the bit cut out of the insides. Quite amazing.

Tim (too)

What an amazing process, those bits look like a CGI of it, how long does it take, and does the part need any further treatment?

All done over night, I understand. The machine is set up in the evening and allowed to run on its own until the job is finished - then ready the next morning. We have used EN8 steel and we will not treat it any further.

Here is the old alongside the new. It fits very well. Tony is just left to make the oil pick up and the locking screw. We will soon be ready for reassembly.

Nice job.

I know the modern techniques are superb, but it doeas make you appreciate the skill of the original manufactures.

Nice job.

Tim,

A Proper Job ( said in a Devon accent ) :-D

A very impressive process, how wide is the "cut" ? It only looks about 20 thou.

Just put a Feeler Gauge into the cut - 15 thous only. Really amazing!

Just put a Feeler Gauge into the cut - 15 thous only. Really amazing!

Thanks, amazing technology.

I use these guys sometimes for work related jobs (turbine components) but the website has some useful info if you're interested in EDM.

http://www.wmccm.co.uk/WMCCM/DesktopDefault.aspx?tabindex=0&tabid=2040

Chris

Thanks for that. Always useful to know who can do these sort of jobs.

Tony has now made the oil scoop and the locking nut.

Proper job!

We have the correct bearings (thanks Chris) so we just need to arrange a day when all of us can get down to Devon to put the thing back together. It is going to be a busy day. Then what is it next chaps? Water pump or torque tube?

Tim (too)

I thought we could save the oil seals for the half shafts, but they were a bit past it, so Steve made up some new ones.

He first turned up a tapered plug of 1 7/8" diameter from an odd piece of timber. Then cut a leather disc with a 1 1/2" hole in the middle and soaked it in water overnight. He carefully pushed it over the plug, stretching it as he went and working it to shape. After 24 hours, it was dry enough to be removed when he punched out the bolt holes with a wad punch. No problem at all in the end.

With the diff just needing to be put back together (and all three of us in the same location at the same time to do it), Steve has been having a look at the carb.

Now, we took this off the inlet manifold and it all looked very good.

But on examining it further we see that it is actually a Zenith 36UY and not a bit like the one in the manual:

which Ben confirms is a Claudel Hobson. We could probably make it run on the Zenith but probably not very well - as the engine was used of course to run a fire pump and not a lorry. So if anyone comes across a 36 Claudel Hobson, do please let me know.

Thanks

Tim (too)

As I mentioned some time ago our engine was missing its Water Pump and over the years we have been looking for one without success. Now there is another surving Dennis three ton subsidy lorry, but the water pump was stolen off that during the trucks restoration. The owner adapted a modern pump to go on it. We considered doing that but discounted the idea as we wanted to be as correct as we could.

Now, we heard of another surviving Dennis subsidy lorry, although we think it was a post war build and the owner still had its water pump. Steve made contact, but the owner told us that we would be welcome to have a look at it, but the pump had been stolen. With the intervention of our good friend Mick, we discovered that it had been removed by the owners Father (since deceased) and was in another part of the workshop.

Steve and i went up to have a look with the intention of drawing/photographing it in order to make a pattern for a copy. This was how the Dennis looked when we went to see it. it was in the darkest shed imagenable and the only light we had was from the camera flash:

The water pump assembly was left with us to photograph. Here are a few of the several hundred photos we took - just to give you an idea of the complexity of the project:

A bit of wear here:

As you can see, not an easy thing to copy. Anyway, from the photos and the measurements, Steve made some drawings. Seven in fact:

We are a bit disappointed not to have an original water pump, but with some work at least we will have an exact copy.

We have been putting off this task for a while hoping that one would turn up. After these years nothing has, so it is time to bite the bullet. Steve has just started making the patterns.

Tim (too)

Some serious mice in that shed ! Chewing the tarpaulin is normal but they really got their teeth into that impeller, didn't they ?

I think that you were quite brave going in there in the dark !

Blimey!

Must have been a good few hours work in doing the drawings. All hand drawn I'm fairly sure.

Not something you see much of these days with CAD.

Do you soak the leather washers in anything before fitting? Mineral oil is the kiss of death for leather. I always soak the washers for Tilley in Nikwak conditioner. Keeps the stuff supple and also seals the leather.

All hand drawn I'm fairly sure.

QUOTE]

 

Quite right! I find that scheming things out by hand at full size is a lot easier and quicker than trying to do it in 3D. I can concentrate on the drawing rather than on how to work the software too!

 

Steve