1914 Dennis Lorry

Merry Christmas

Merry Christmas

 

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A good thing you have chocked the wheel, other wise it may run of with you chasint it yelling ho ho ho...:-D

A good friend of mine assured me he had a spare Dennis 2 ton clutch in his shed so we visited to have a look. After a couple of hours of shunting vehicles around and dropping the boiler out of a steam lorry we spent a few hours emptying a shed to find the clutch (and some parts for his projects!).

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The crack and broken rim was a bit of a concern and where the clutch stop acts it has worn down to less than 0.1"

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Removing the woven lining showed even more damage. I will have to decide if it is worth investing in an AC TIG welder to have a go at repairing it or just build it up into a pattern with ply and filler.

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I already have clutch stops and these have been blasted and primed. The friction linings need to be replaced.

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forget using the argon set on that ben

I doubt it`d have it...

forget using the argon set on that ben

 

I doubt it`d have it...

I went down the new casting route. It still needs machining.

We have been catching up with friends and family this Christmas so progress has been fairly limited but I hope to spend a couple of days on the lorry before returning to work. I have been preparing for the gearbox work and have assembled nuts, bolts and washers to fix the repair frames.

The plan is to spread metal reinforced epoxy on the horizontal surfaces and then clamp the fabricated frame into place so the epoxy can take up the irregularities. For the rear (and mostly complete) mounting I intend to only drill through the vertical faces of the mountings and then fix through with large washers and 5/16 BSF fasteners. Before tightening the bolts I will probably use a syringe to inject low viscosity epoxy resin into the crevice between the fabrication and the casting.

The front fabrication will have to follow a similar procedure but there is so much of the original casting missing that some of the fixings will have to pass thorough the main section of the gearbox. This will require more care to avoid interfering with the gears and obviously all these bolts will be fitted with slotted nuts.

I have been scrubbing the gearbox clean to prepare for this work.

Do you expect any corrosion/electrolysis problems in the future? You have given me an idea for my Leyland gearbox. Thanks. Robert

Do you expect any corrosion/electrolysis problems in the future? You have given me an idea for my Leyland gearbox. Thanks. Robert

My electrochemistry is a bit rusty (sorry for the pun, I could not resist). The aluminium will certainly be sacrificed in favour of the iron if the passive aluminium oxide layer is broken down but this is not much different to the situation with the bolts and cover plates. It would be nice to use another metal to protect the aluminium but it would have to be something like magnesium (sodium, calcium, barium, potassium and lithium also have potential) so I don't think it is a practical solution.

I think the key to protection will be excluding the electrolyte and I think paint will suffice for this along with the water repelling effect of the various oil leaks.

The crevice formed between the steel fabrications and the aluminium casting could lead to quite an aggressive environment as the oxygen is consumed and the hydrogen ions build up, reducing the pH (making the water in the crevice acidic). I hope that filling these gaps with epoxy should stop this happening.

Anyway, I have made a start on the gearbox repairs as we had a day without visitors. Starting with clamping the first frame in place, drilling the easy holes and fitting the bolts.

Then some of the more difficult holes. The 5/16" drill had to be shortened to half its length so I could get it into the space.

I then removed the fabrication again and started to mix up some "marine metal"; a reinforced epoxy I happened to have on the shelf.

We first applied a few dabs of the epoxy across the faces before a first trial fit of the fabrication. This allowed me to see how far each dab spread and allowed me to add a little more where required.

I then had slightly too much on one side and could not pull the fabrication down so had to remove a little before the final fitting.

The epoxy that extruded out in various places was scraped back and the nuts were slightly tightened.

I will let this reinforced epoxy set before attempting to inject a low viscosity resin into all the crevices. I used up all the "marine metal" I had in stock so it will be a while before I fit the other fabrication.

Did you consider making the fabricated mount out of aluminum?

The gear box will continue to corrode with electrolysis as it is attached to other steel items about the chassis and the positive ions will continue to move to the lesser reactive metal ( Aluminum). Your method of repair has given a fresh lead to rebuilding similar damaged gear boxes here.

Doug

Did you consider making the fabricated mount out of aluminium?

 

If I had the facilities to make the support in aluminium I probably would have done. I would probably have wanted the aluminium to be thicker than the steel I have used and this would have given me problems getting the mounting bolts in so the design would have to change a little.

My first attempt at injecting the low viscosity epoxy did not go exactly to plan. I filled in the holes with putty and tape but found the epoxy still found ways to drain out. I then used some epoxy putty to fill the gaps the epoxy had been escaping and then had another go. In the end it was reasonably successful but a fairly slow process.

It also took a little while to clean up the mounting holes. Partly the result of them being filled with blue tack and epoxy and partly as a result of the holes in the fabrication not lining up exactly.

I then aligned the front fabrication and had a bit of a look at where the bolts could pass through the case. The missing mounting lug lines up with the detent plungers which does not leave a lot of space to get a fixing in. I will put all the gears in place to make sure I have accounted for everything before finally drilling these holes.

A trial fitting of the gears to make sure they would not interfere with any of the proposed fixing locations

Aligning the support frame and drilling for bolts.

The same procedure with "marine metal" was followed. The bolts through from the oily side were inserted with thread sealant and cross drilled for split pins.

I will probably try to get a couple of further fixings through.

I had a spare lamp mounting spade cut in the last batch of laser cutting but had not decided by that point exactly how the rear lamp bracket was meant to work. I studied the factory photo a bit more and it appears to mount off the rear timber bearer alongside the number plate. You can see in the photo that it loops down and back up and there has to be enough space to get the lamp on and off.

So I made up a T shaped bracket to mount to the bearer and heated up some EN3 steel before bending it around an old piece of gas pipe that seemed to be about the right size. Then it was just a case of trimming it to size and welding it all together. Finally I put it through the blast cabinet at work to prepare for painting.

The tail board brackets and the lamp bracket then had a coat of primer.

The sides of the cab are made from timber planks around 19" wide. These looked difficult/expensive to find but I saw some on an auction site and placed a low bid. To my amazement it was the winning bid so we had a trip out to collect them today.

There are no firm plans for the cab yet; I know how it should look and can get most of the overall dimensions from the drawings and photos. However most of the actual structure is not defined.

This photo shows were the gearbox position. The petrol tanks is positioned 2" above the chassis rails under the seat; it does not leave great access to the gearbox.

The gearbox I have is actually the post WWI variant where they fitted a tap for checking the oil level but on the one originally fitted it must have been a bit fiddly to check the oil level.

After checking it would not interfere with the selector rod and fork it turned out I could get another fixing on the side where the mounting lug is missing.

And a further small bolt at the front. I don't think any more would be a benefit.

I have filed back the excess "marine metal" in a few places.

Another job I wanted to start on was the headlamp bracket. There is only one and it was not fitted in the factory photo so I have used this example and the surviving fire engine ones.

I am sure someone on here will be able to explain what the markings on this lorry signify.

The first part of the lamp bracket was to turn the profile from some EN3 steel.

Then heat it up and bend it (mostly around a big piece of aluminium pipe). There was a little swearing involved as it did not go exactly to plan but I was able to put it right with a bit more heat and bending. I failed to take any photos of it when it was wonky.

The next part of the bracket was made by cutting some more steel with a hacksaw.

The flange that fits to the chassis was made in a previous batch of laser cutting so I could just v out the gaps and weld it all together.

Then use the angle grinder to dress back the welds.

And a trial fitting.

Before a little bit more tidying up with a file and emery cloth.

It is now ready for blasting, priming and painting.

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I am sure someone on here will be able to explain what the markings on this lorry signify.

Quite a lot of Sankey wheels in that photo, but I only know of one set in preservation, and that on a vehicle that has basically never been off the road. I wonder if they cope badly with being left in fields or under houses?

Quite a lot of Sankey wheels in that photo, but I only know of one set in preservation, and that on a vehicle that has basically never been off the road. I wonder if they cope badly with being left in fields or under houses?

The Sankey disc wheels are quite distinctive. The correspondence between the London Fire Brigade and Dennis Bros (who were under Ministry of Supply control by this point) stated they had to use the disc wheels as nothing else was available and I guess they were used here for the same reason.

I think there were fewer that 100 Denis vehicle produced with these wheels and as two have survived that probably exceeds the average!

The type of Dennis lorry in this photo did not meet the subsidy specification so it is interesting to see that they were being purchased and I can only assume this was also just a case of what could be made with the available parts.

I decided to machine the casting for the fuel filler cap that has been sitting around for quite a while.

Then fitted it to the tank.

As it was not raining yesterday I pushed the lorry forward so I could line up the tail lamp bracket and drill the rear bearer for the coach screws. It is now two years since I started putting the lorry back together so it is nice to think that I may need a registration number on that plate at some point this year.

The gearbox breather was missing the brass hemispherical umbrella when I received it.

I thought the easy way to make this would be to press some brass sheet through a hole with a ball bearing. My disc was of diameter=pi*ball diameter/2

My first attempt ended up a bit too frilly.

For the second attempt I reduced the diameter by nearly 1/4" so there was not so much excess material to be left as frills and that was much more satisfactory. After pressing I soldered a 3/16BSW screw in the centre.

I rubbed the cap on a file to level off the rim and then cleaned up any imperfections with some emery cloth.

Before giving it a quick polish.

There has been a bit of blasting, priming and flatting back as well but those photos are a bit dull!

This week has mainly been taken up by preparation and painting. The front wings have had another coat.

Although not originally fitted I have cleaned up and painted a pair of mirrors.

These clevises and levers will be used to connect up the ignition timing and throttle. None of them came with this vehicle but most are Dennis parts and it will certainly need a few more parts to make it all work properly.

The shaper has been used to tidy up the ends of the universal joint hub casting.

I need to carefully mark it out to define exactly where the holes need to be.

This piece of angle fits to the back of the cab and follows the roof radius. It was made by cutting slots and welding them back together. It has had a coat of primer and will now be stored until needed.

For a while I have been thinking a modern AC/DC TIG set would be the magic wand needed for the repair of aluminium parts. I booked a demonstration of a reputable make of 200A capacity; it was a joy to use on nice clean aluminium and I could imagine fabricating all kinds of parts with one.

I took with me the stuffing box for the gearbox selector rods; previously I had warmed it up with a propane torch until the oil stopped sweating out of it and given it a fairly thorough cleaning. Using a 2.4mm tungsten all we could get was smoke (both white and black) and fireworks. We eventually tried a 1/8" tungsten, gas lens and the balance to maximise cleaning but only managed to melt some of the aluminium and managed to blow the gas shroud apart. So I came away without a TIG welder.

When I got home I decided to go down a different route with the repair. Starting by opening up the crack.

Then using an aluminium stick welding rod to put a little bit of strength back into the casting. I did not dare try to weld the thinner parts. These rods have to be used "electrode positive" to give the maximum cleaning effect (destabilising the aluminium oxide). They are nothing like regular arc-welding to use; the flux is incredibly aggressive and leaves a really hard (almost glass like) slag over the weld. I also find I have to snip the flux off the end of the rod to be able to get it to strike. Finally as 2/3 of the arc energy is at the positive electrode it is consumed really quickly. It is not elegant but it does impart some strength.

You have to scrub all the slag off or it will corrode the aluminium away when it gets damp.

The next step was to machine 1/4" off the back of the stuffing box to remove what was left of the original mounting flange. This left enough of the existing casting that the new flange will not be taking any of the force compressing the gland stuffing. The bit of aluminium in the left hand hole is where we melted it with the TIG welder.

Then I machined a slot in the new flange that was laser cut previously. I cut three bungs of acetal to align the two parts where the selector rods fit

Before gluing the two parts together.

The flange was also secured with four countersunk screws.

Threadlock adhesive was applied to make sure they do not work loose.

Marine metal was applied to hopefully prevent oil leaking from the crack and to generally tidy up the appearance.

In order to make the bore round again where is had been deformed during TIG welding the stuffing box was clamped to the table of the milling machine and a centre indicator used to make sure the spindle was correctly aligned with the bore.

Then a boring head used to machine the bore until it was once again circular.

A coat of paint was applied to tidy up the appearance and offer some corrosion protection.

And now it is ready for fitting. It would probably have been as easy to make another one but it is nice to rescue as many original parts as possible.