Something that had been troubling me since the start of my planning was how I was going to mount the pilot wheels. There's not a lot of room for the length of a conventional pivot that would be used in most models. In reality this wouldn't swing and I'm not planning on R1s on my line but I wanted a good amount of flex in there so that nothing was holding the drivers off of the track.
Kent Garden Rail delivered my Lilliput spoked wheels and I found a pair of flanged sleeves to suit the diameter of the axle. The axle stubs were sawn off as this will be an inside bearing job.
the first step was to make up the bearing block. The width of the block means it can swing 5mm in either direction within the frame. The wheels then have 4mm to slide in either direction before the inside face touches the frame. A box was made up from plasticard. A 5mm hole was drilled into each side and used to align the box while it was was assembled. Once it was a solid piece, the final 7.5mm hole was drilled through the entire part to ensure the alignment of the bearings.
The bearings were inserted dry and the axle pushed through to check everything was straight. Once I was happy with that, they were superglued into the block. The wheels were then pushed back onto the axle.
The pivot will also be made from plasticard. I would have preferred to make the whole thing from aluminium or steel but my engineering supplies are currently all at my parent's house and unobtainable. It might be another candidate for printing in the future.
Owing to the space constraints the pivot will essentially be backwards; the wheels will swing around a point forward of their own axis. The large amount of side play in the wheels is needed to ensure they maintain the correct arc in relation to the driving wheels when on a corner. I found it easier to think of it as the rear half of a radial four-wheeled bogie.
The swinging link was measured out. It looks a bit bulky but this pivots around another top hat. This ensures I can have everything tight and secure without clamping the swinging link.
The sides were cut and the whole assembly fixed to the bearing block. It all seems quite solid so I imagine it will be a case of improving once this wears out. The pivot is bolted through the base plate, through the top hat and all tied together with a lock nut.
