W&M railbus failure

[rorz101uk]

2 hours ago, PJT said:

 

As far as I knew at the time Ultrascale didn't do the twin gear that meshes with the motor worm; maybe they do now.  You'd have to ask them.  I have to say my railbus works very nicely with brass final drive gears, brass intermediates and nylon twin gears.

 

As I said further up the page, the intermediate gear has a clearance fit on its shaft (it's supplied with the shaft), so it is free to rotate on it - which is just fine.  The brass final drive gear needs securing to the axle; while it's a tight-ish hand-push fit onto the axle, its grip on the axle is not enough on its own.  You will need to secure it in place - my method is to file/grind a flat onto the axle, creating a small gap where a tiny fillet of Araldite can bind both to the flat and the bore of the gear.  That's enough to lock it in place, for me anyway. 

 

When you remove the damaged nylon final drive gear from the axle, you will find there are three (from memory) thrust washers either side of the gear, governing the sideways float of the axle/gear assembly.  Refit the washers selectively on the axle either side of the new brass gear, test fitting the axle/gear assembly in its housing in the railbus chassis to ensure you neither have too much float, nor so little float that the gear and axle pinch in the housing and don't run freely.  As it happens, I ended up using the same quantity of washers with the new brass gear as were used with the old nylon one, but you shouldn't take it for granted you'll use the same number.

 

Pete T.

 

Thanks Pete, a purchase next month! 

[PJT]

6 hours ago, rorz101uk said:

Thanks Pete, a purchase next month! 

 

You're welcome.  When you get around to doing the job, if you have any further queries then I'd be happy for you to ask me here or PM me.

 

Pete T.

 

[rorz101uk]

Hello All

 

i just spoken to David at Ultrascale, the parts for the railbus with be discontinuing at the end of the year, if you need your models repaired with part, I’d get them ordered!

[CWJ]

When my W&M railbuses suffered cracked final drive gears I was put off by either the price or the lead time for Ultrascale replacements (can't remember which). So I worked out the gear type from the diameter and number of teeth, and ordered brass replacements from China via Amazon.

 

These only came in a wider size, so I had to reduce them to the required thickness. After a few false starts I did this by mounting the gear on a temporary axle, cutting it crudely in half with the junior hacksaw, then mounting it in the pillar drill and pressing the cut end down on a piece of sandpaper to tidy it up. If you have a lathe you could of course just use a parting tool.

 

It worked a treat and was quite satisfying to do something that could be very broadly described as engineering. If anyone is equally desperate here's the link to the gears I used:  https://amzn.eu/d/3woBKzG

 

Cheers,

 

Will