Trolley wheels

[tramcar trev]

An authorative discourse on trolley wheels.

After the amazing experience of running a tram using the trolley wheel I experimented to try and discover exactly why some wheels jumped off the wire and others stayed on it.

Wheels that are fixed have the advantage that the dragging action along the wire tends to keep them clean but they also tend to climb over the wire and flick off if the wire presents itself in any position other than directly ?into? the wheel.

Wheels that rotate have the disadvantage that the rolling action tends to press dirt into the collecting face of the wheel but have the advantage that even if the wire is presented at an angle to the wheel they tend to stay where I want them especially if there is a little axial play in the wheel. The wheels can be easily cleaned though with a cotton bud and some metho.

The wheel diameter also has a bearing on this too, 6mm dia trolley wheels will de-wire at the least provocation where as a more reasonably sized 8mm wheel with a thickness of just under 2mm with a 1.5mm groove (just over 2 times the trolley wire diameter) seems to be ideal and I have adopted it as standard. Maybe not strictly to scale (5/16? diameter) but they look quite ok and only the most robust rivet counter would notice?.

I knocked up a batch of what started out to be 9 but ended up as 6, 3 being ?lost? in the manufacturing process?..

The ?harp is from 1/8" sq brass tube with a small length of 3/32" round tube soldered into it that has a 1/16? bore which will be soldered onto the ends of the trolley poles. The wheel slot I machined out on the micro mill using a 2mm carbide ?Dremel? cutter?

The axles are held in place by simply inserting the sharp end of a scriber into the centre hole and pushing down with a bit of a wiggle; this expands the tubular axle into the hole in the ?harp? and holds it secure. Electrical continuity is ensured by then carefully placing about 3/5ths of one nano skerrick of solder paste on one side and carefully heating it up to allow it to bond the joint.

I wish I had paid for the CNC machinery now?.

Ok now the tricky bit; stringing the rest of the overhead?.

And the collective noun for a group of trolley wheels is?????​

 

[Rhinochugger]

The last model railway exhibition I visited at chi, had a guy with some 1/12th scale trams, all running with trolley poles.

His occasionally came off, but then that's prototypical. I'm too young to remember trams (except Blackpool) but I was brought up in a big trolley bus area, and remember the things grinding to a halt at busy road junctions and the conductor having to get a long bamboo pole out, that was kept in a tube underneath the bus running the length of the bus, to re-rail the trolley

 

[Dtsteam]

Ohhh they're really good Trev - can I order a couple of gross ?
Seriously, the way you've built the o'head by soldering the wire to the edge of an etching means that you can afford a deep groove in the wheel and therefore more reliable overhead. Mind you, better string a frog and see what happens....
As to diameter, you're on about an 8 inch wheel, but I'm pretty sure I've seen pictures of wheels so large they were spoked (and therefore bigger than that) so you must be in the clear.

 

[tramcar trev]

Yes. I wish I had CNC machinery, I could have made spoked wheels.....

 

[trammayo]

Very nice wheels Trev

There are two types of "wheeled" trolley heads - fixed and swivel. The fixed head uses large diameter (approx 6") whereas the swivel head uses one nearly half that diameter. I have a wheel from the swivel head type (see if I can find it and take a piccy). It is the angle of the groove that helps keep it in place round curves.

 

[trammayo]

Here's a pic of my swivel head trolley wheel ...

 

[tramcar trev]

Well no wonder you have it ; it's worn out
But the pic clearly shows the profile of what the groove would have looked like in its "heyday" best described as more of a V with a rounded bottom. Yes and obviously this is going to help keep wheel on wire far more so that if the grove was either semi circular or U shaped. I tried to take a micrograph of mine to ensure they were up to scratch but they are too small to photograph easily..... Just a tick while I jot down on my xmas gift wish list.... Scanning electron microscope
8" wheels were common in the early days and look rather elegant....

 

[dunnyrail]

Trev! Very nice turning. Just a question (another I am always asking them) do you get get "Singing" with the wheels. We do get some singing on the Ruschbahn but only in a hidden part of the line. Must investigate why we do not notice it elsewhere. But thinking about it as all our Locomotives are sound, the area that you notice the "Singing" is where the Train is about to pop out of the open through a Tunnel Mouth and into a hidden area.
JonD

 

[trammayo]

You're right about it being worn It escaped the melting pot to become a pulley for a pull frog!

I reckon you're doing all right without an electron microscope

 

[tramcar trev]

I didn't notice any sing at all, maybe there was too much ambient noise. In real life singing is more pronounced where the trolley wire is a bit slack and hangs down in a catenary type curve. Also its far more pronounced in quieter surroundings.... Another reason is that some trolley wheels actually had roller bearings in them and the current was picked up by a phosphor bronze wiper running on the flat side of the wheel... now the roller bearings were not sealed and a bit of dirt in there and you have an entire Welsh Male Choir.... You could also expect some noise from trolley wheels with worn out centres...
I'll be happy to just get it set up 8| then I'll worry about sound effects. I do have some recorded ready to use though....:wave:

 

[tramcar trev]

I have been tweaking the trolley wheels. Based on the theory that if the trolleys come off the wire in a regular location that there is a fault with the overhead but if the trolley arbitrarily dewires there must be a problem with the wheels….

A little experimentation and I came up with version 22C trolley wheels. The wheel is .5mm wider and the groove is also far wider and the inner diameter of the wheel is now 3.25mm. The wider wheel copes with a lot more angular approach of the wheel to the wire and the deeper sheave means that small burrs do not cause a dewirement…

I have also replaced the copper tube axles and instead now use a piece of .5mm Phosphor bronze wire as an axle, Phosphor Bronze is self lubricating so the wheels wont “gall” on their axles as was the case with the copper axles….
I shall adopt this as a standard. Next time ALDI have one of those little ultrasonic cleaners for $10 I'll grab one to clean my small parts......I just hope they last the distance.....

​