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1911 Dennis Fire Engine 3035


mammoth

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You need some sort of embiggening chamber. 

As for the welded-on parts, I think that I would be looking to plasma-cut off the modern wheel and then machine off the weld (and remaining bits of wheel) on a lathe. 

Though the "modern" wheel looks plenty old, too. 

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Ha, the thought of turning up the dial on a 3-D printing machine crossed my mind as well.

I think you are right Andy, however separating the hub from the axle beam will need to be achieved first. (Barry, can you advise?)

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1 hour ago, mammoth said:

I think you are right Andy, however separating the hub from the axle beam will need to be achieved first. (Barry, can you advise?)

Having taken the wheels off of N-types more often than most myself....

You should be able to just undo the nut. 

 

The half-shaft is anchored  inside the differential. 

The hub runs on a bearing on the outside of the axle tube.

The "spider" is keyed to the half-shaft and held on by the nut. 

The nut clamps the hub between the spider and the thrust bearing ring. 

The spider transfers the torque from the half-shaft to the hub. 

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IMG_0085.thumb.jpg.05df774b1062afe757a237fdac5491d2.jpg

These are pictures of my hubs. The wooden wheel is clamped between the hub which dogs into the drive shaft and the brake drum. On my machine both the holes in the hub and the brake drum had fretted oval so they were drilled out and oversize coach bolts made and fitted

IMG_0086.jpg

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This is one of the actual wheels. At some time the original full width hoop has been removed and two new bands were fitted at either edge of the wheel these bands were then screwed into the wooden wheel. The wheel with the bands was then inserted into the tyre. As it was slack and not a press fit the bands were then edge welded to the hoop of the tyre. To make extra sure that everything was going to hold together coach bolts were then put through the felloes into the actual tyre  band and the nuts countersunk into the rubber! All of this was done at least 50 years ago.

So the plan being is to have new wheels made with the correct size hoop for a tight press fit into the tyre hoop.

 

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One of the great mysteries of these components is that I am convinced that the brake drum was drilled for the coach bolts using the hub as the template and then kept as a pair. The drilling of the hub (even allowing for the difficulty in picking up the true centre of the holes due to the fretting) does not seem up to the usual Dennis precision. When I made an aluminium plate template from one side hub there was no way in which it was going align with the  holes in the opposite side hub.

 

More Wheel pictures can be found on this ED810 Flikr page:

 https://www.flickr.com/gp/asciidv/R9638M

 

IMG_0097.jpg

Edited by Asciidv
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It is all starting to make sense now. Aiming for a 720mm tyre size. Are the spokes connected to the felloe with a 1" dowel, and  how thick are they? They look to be of parallel thickness and width, except perhaps for a bulge at the brake drum fixing. What is the advice on thickness of a band for the wood wheel?

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Steven, the spokes are parallel at 4 inches wide with the wheel being just over 6 inches wide. I am just preparing some fully dimensioned drawings for you. It did cross. my mind whether CNC routers can run with 4” long cutting tools as one would make short work of the spokes?

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5 minutes ago, andypugh said:

Try eBay for long-series cutters. https://www.ebay.co.uk/itm/193879967564 for example.

Thinking further: https://www.ebay.co.uk/itm/174707121469 in a CNC horizontal mill might work. How tight is that internal radius? 
I do have a  long 25mm cutter going spare:  https://photos.app.goo.gl/U8TiSe9iKoyeYzow8

Throwing money at a wheelwright might be the more expedient solution. 

If you do want to make your own wheels (and it is something that I have always fancied a go at myself) then watching "Engel's Coach Shop" on that YouTube might be rather informative. 

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Andy, I am thinking of going to a traditional wheelwright for final assembly but as he makes all his spokes by hand it seems an unnecessary waste of time and money. The same goes for the felloes.

Rather than mucking up my VMC with wood dust I am now tending towards commercial CNC routing job shops who have hard wood experience. I need 24 spokes and if Steven joins in that would be 48 spokes.

 

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It also appears that the brake drum mounting ones have a definite bulge, rather than just a lesser degree of radiusing where the bolts go through? 

Possibly made with a form tool originally? 

Anyway, the answer is probably to make a copy machine, like this one:

 

 

 

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14 minutes ago, Asciidv said:

Andy the profile of the spokes is actually quite complex.

That's why I am suggesting the copying machine. 

If you do make your own spokes, then my watching of Engelscoachshop would lead me to suggest not cutting the tenons, or leaving them very short. That seems to be their main adjustment. 

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Wow, I have been away and come back to see this amazing computer work. I knew it would be complicated hence all my questions. These wheels do not have a wagon wheel type hub for the spokes to tenon into so the conventional wheelwright technique does not apply.

Next question:- there are two narrow steel bands on Barry's example and the thought was that they were not original. On the other hand  a single very wide one might be a big ask to slip over such a wide wheel in the usual heat shrink style.

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46 minutes ago, mammoth said:

 On the other hand  a single very wide one might be a big ask to slip over such a wide wheel in the usual heat shrink style.

You are right to worry about that, Steven.  We did my front wheels on my Aveling.  They are 1000mm dia, by 200mm wide in 10mm thick MS.  This is the amount of heat we needed, and still struggled.   There is coal in this fire, wood on top and compressed air from a lance... and we still just about made it.

PICT0010.thumb.JPG.c1cd9f0b5b05ce04aabf841c66573fa2.JPG

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A less traditional approach might be to  leave the ring unjointed, weld brackets to the join. Pull it up very tight, MIG weld the join and grind off the brackets. This probably won’t pull up as tight as a well-executed shrink fit, but might be more relaxing than a badly executed one. 

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More photos for comparison.

A wide single front on a Dennis hub. It is possible a wider rim and tyre were fitted at some point.

IMG_6448.thumb.JPG.7fc50148fcf2df8466d186e58ca3f899.JPG

 

An "original" front. I just cleaned it up and painted it. New 100 for 720 tyre. It was necessary to press the tyre onto the rim with canvas between to get sufficient tonnage.

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A professionally rebuilt front. All new timber with original hub and steel rim.

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Some of the timber that was replaced.

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Note the felloes are approximately the width of the tyre fitted. The heat shrunk rim is usually wider. In addition to protecting the wood from kerb damage this is also essential for pressing on the tyres - you do not want to be applying the load to the timber.

IMG_6450.thumb.JPG.3830035d7712543840c7cd8f02d242d2.JPG

 

An "original" or at least not rebuilt rear. This is of much heavier construction than typically seen on a 3 ton lorry. Not the additional bracing band for the brake drum and how much wider the spokes are than the felloes. Heat shrunk rim protrudes on both sides of the wheel.

IMG_6458.thumb.JPG.a179bb0788c3f97b2398c9670f52e04e.JPG

 

Rebuilt wheel, this is a copy of what was removed but a different design to the other side. Note the spokes are much narrower.

IMG_6457.thumb.JPG.f2d6bac6456c036c864ca1e1bf5248ca.JPG

 

The "as found" spokes and felloes.

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On this vehicle twin 120 for 720 tyres were specified. Note the felloes are approximately 230mm wide. The new ones ended up slightly wider. 

IMG_6454.thumb.JPG.89696ed736aab4b8bdf8282d58e25d83.JPG

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Thanks Ben, seems there has been a degree of freelance design happening. Also, all except the first are 14 spoke rather than Barry's 12. The idea of a 'pull-up' band would likely be part of the plan to tighten and test the wheel prior to a shrink fit.

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Ben, when I have had cast wheels rubbered the tyre bands were not removed but were wound in situ on the wheel and then the whole wheel put into the autoclave. When you had your tyre bands re-rubbered could they accept the tyre band directly or did it have to be mounted on a donor cast wheel? I am under the impression that the conditions for vulcanisation would always be too severe for a wooden wheel.

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4 hours ago, Asciidv said:

Ben, when I have had cast wheels rubbered the tyre bands were not removed but were wound in situ on the wheel and then the whole wheel put into the autoclave. When you had your tyre bands re-rubbered could they accept the tyre band directly or did it have to be mounted on a donor cast wheel? I am under the impression that the conditions for vulcanisation would always be too severe for a wooden wheel.

Some companies will apply the rubber to a loose band, others will insist that they are mounted. Certainly putting the wooden wheel through the autoclave for the vulcanisation process will destroy it.

I have led Steven down the wrong track with the wheels for ED-810, that has the lighter weight axle (used on 30cwt lorries). He appears to have the rear axle used on two and three ton lorries with larger hubs. It should all become clear as he dismantles what remains of the wheels.

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