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Offline Toosmall  
#1 Posted : 28 July 2021 10:00:27(UTC)
Toosmall

Australia   
Joined: 26/07/2021(UTC)
Posts: 27
Location: New South Wales, Newcastle
I have machined groves into the wheels of some of my locomotives. This was quite challenging having to create a cutting tool ground to the right width and angle. Also get the cutting height just right, the small radius of the wheel changes the tangent of the cutting tool to the wheel if the height is not exactly right. Also used cutting fluid. Initially I did ruin a couple of wheels, but used a loco that I had already butchered. Should have used a lathe collet chuck with jaws the right diameter with a larger percentage of the circumstance of the wheel to avoid the jaw marks, but as is, there are no issues with running.

The rubber for the tyres is 2x reduction heatshrink tube. It's not heated, but just a bit undersized and stretched over the wheel. If you heat shrink it, it gets too thick and has an uneven thickness.

I did have to cut quite a few tyres with a scalpel blade to get the right width. It is surprising the difference 0.1mm tyre width makes in this scale. Also some of the heatshrink tube varies in thickness a bit, so you end up with a wobble. But it actually doesn't take that much time to find good sections.

Once done the tyres do last, so no issues there, except for one time with an excessive oil spill. On a 4 axle locomotive I put the tyres on the third axle as this pushes down on the track the most and is more centred so gets weight from both ends. The 3 remaining axles for electrical pickup have worked fine.

With a bit of extra lead you can tow just about anything, I haven't actually tested a straight line 2% gradient, but we are not towing 240 carriages with iron ore to Dampier in Western Australia.

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thanks 4 users liked this useful post by Toosmall
Offline cookee_nz  
#2 Posted : 28 July 2021 11:41:37(UTC)
cookee_nz

New Zealand   
Joined: 31/12/2010(UTC)
Posts: 3,668
Location: Paremata, Wellington
Strewth, that's dedication to the extreme. Good job, but I have to ask, why? - what was the problem that led you down this path?

Normally the weight to tractive ratio is fairly good with Z, the rolling stock weighs hardly anything and the Loco's relatively powerful for their size.

On the other hand, looking at your hopper consist, I guess there's a bit of weight in those and if you have a climb perhaps it was a bit much?

Good effort all the same
Cookee
Wellington
NZ image
Offline Mman  
#3 Posted : 28 July 2021 12:33:37(UTC)
Mman

United Kingdom   
Joined: 23/05/2021(UTC)
Posts: 71
Location: England, Guildford
I have thought about doing this since I bought a Rokuhan loco with traction tyre and found out how much more you could haul. I followed that up with an ebay purchase of an axle (with gear) and two wheels that had a groove and traction tyre. This was from the USA to UK and it worked out very expensive with import duties, VAT and the Royal Mail’s handling charge and although it similarly improved the loco to which It was fitted the exercise was too expensive to repeat.
I see you have fitted tyres to both wheels on the axle, this must have mixed results, ie fine on the straights but a handicap on curves with two wheels with good adhesion but one must slip due to trying to rotate at different speeds.
I see that Rokuhan do their Z tyres as a spare part and I intend to get some of those and have a go at cutting a groove to suit. I have a Unimat 3 with collet chuck and hope something like a parting off blade will suffice.
ChrisG
Offline husafreak  
#4 Posted : 28 July 2021 17:15:49(UTC)
husafreak

United States   
Joined: 09/04/2019(UTC)
Posts: 342
Location: California, Bay Area
I always love to see the engineering work some of you can do so thank you and good job! It became obvious to me early on (in Z) that my Rokuhan and AZL locos could pull much more than my Marklin ones so it makes sense to modify the locos, like yours shown, that can pull a lot of cars in real life. While a small steam loco with a few small cars also looks good on a tiny layout they don't need the traction. For me the one of the coolest things about Z is the long trains that can be run!
Offline Poor Skeleton  
#5 Posted : 28 July 2021 18:05:48(UTC)
Poor Skeleton

United Kingdom   
Joined: 09/10/2015(UTC)
Posts: 373
Location: England, Cambridge
Wow!! I’m impressed by your bravery and machining skills! Have you found that electrical pick-up suffers? That would be my concern with doing this. (Well after the fact that I’d most likely bugger it up!)

Have you tried this with steam locos at all? They seem to be the ones that most suffer from poor traction.

Good job!


Chris
Offline Toosmall  
#6 Posted : 29 July 2021 04:00:40(UTC)
Toosmall

Australia   
Joined: 26/07/2021(UTC)
Posts: 27
Location: New South Wales, Newcastle
Thank you for the comments.

The tyres came about simply due to a comment. Why doesn't Z gauge have tyres like HO! Well let's give this a go. I thought it would be an expensive exercise as it would be a steep learning curve as there is a fair chance I would destroy a loco or two in the process. One never gets these things right first time. If you never give things a go what's the point of being here. Let's be honest, there are enough crap runners, so why not sacrifice them.

My Dad had a few lathes, but I ended up doing the wheels on a tiny desktop rubber band 3 speed lathe. It was the best solution for clamping the wheel with the chuck I had at the time. The bevel alone on the clamping edge of a 200mm chuck was larger than a Z wheel, so that was not possible to get the cutting tool in close enough. You are down to fractions of a mm to get clamping right. Often on these types of jobs you first need to design the tool so you can actually create the finished product.

It wasn't actually that difficult, but you have to be prepared to sacrifice things. I had a few locos that were crap runners, so I thought I would murder them for parts.

I have mostly bought 4 axle locos as they seem to run the best. 6 axles are ok with 4 axles actually driving. As much as I like steam locos I have avoided them. Probably also due to the fact that funds only stretch so far. We all know the cost of Z, but it is worth every cent.

I don't think steam locos would work that well with tyres. At the very least as only 2 axles actually drive, the remaining axles are a tiny bit raised, I think you would need to create electrical contact elsewhere, a bit like the ICE carriages and wire them back to the loco. Nothing is impossible. Diesel & electric locos have 4 driving axles, so you only loose 1/4 to electrical contact with tyres, and the bogies by nature give far more flexibility for movement for best contact whether it's traction or electrical.

Let's not waste offcuts after massacring wheels! With the loco "offcuts" I created a 6 pole twin engine loco. Motors are offset 60° as the 3 poles on each motor are at 120°. In principle turning two 3 cylinder engines into a straight 6. What more could one ask for, for ultimate torque and smooth running. Not only are there masses of silky smooth torque, the "six" pole motor is very nice at low speed. Z twin engine, traction tyres and lead, could it be improved... well I have got a prototype which could be merged.

The end of each motor's drive shaft was half filed away so they overlap. Then a spare gear clamping the two ends together. This is a very nice runner.

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