Revamp of Great Western Railway's Small Prairie 2-6-2 Tank Engine No.4566

 

Introduction

I built my model of 4566 in 1987 and over the years it has suffered a number of minor knocks and loss of parts, this is a down-side of being transported around to various exhibitions. Despite this, it is still running well - it always has been a good runner: click here for an example.


The oldest photo I've got of 4566 - taken in 1992

 
 

The Revamp

 
 

The latest outing of 4566 on 15th March 2011 resulted in some more damage during transportation.  Upon inspecting the damage in the cold light of day, I decided the time was ripe for a revamp i.e. replace missing parts and add those things I intended in the the first place, but somehow never got added for one reason or another. Note the 24 year old Mashima motor still performs well. The plunger pick-ups (supplied in the kit) were dispensed with fairly early on, as the springs were excessively strong and made pretty good disc-brakes! Also note, in the following photo, the rather excessive amount of Araldite used to ensure a good joint of the tank-sides to the footplate - I hadn't at that point got to grips with soldering Whitemetal.

4566 was built from a Springside kit and being made of cast Whitemetal weighs a ton! When building, I realised that the smoke-box, boiler, firebox, back-head. cab front and cab roof could be built as a separate unit to the side tanks, cab and bunker; the ability to separate the two portions of the body has been really useful. Here's another view showing the (just added) loco crew - note I haven't bothered to paint the cab floor as it's not really visible when the roof is in place.

With the running repairs completed to the roof, smoke-box and front section of the boiler, foot-steps, lamp irons and lamp, I've detached  the front and rear pony trucks. These suffered the most over the years, and whilst still functional (although the rear truck derailed now and again) quite a few structural, in the prototype, but cosmetic in model form, parts have been lost, not to mention all the guard-irons. The wheel-sets are those made by Alan Gibson and were supplied in the kit. The axles of these wheel-sets are slightly under-size and I added paper packing washers, which was reasonably successfully accept one wheel of the rear pony truck wobbled - probably the cause of the (recently exhibited) odd derailment when running cab first.

And now to the major revamp of my model i.e. the replacement of the pony trucks and wheel-sets. I've chosen to use the super-detailed pony trucks (Brass castings) produced by 'Just Like The Real Thing' for their small prairie kit designed by Malcolm Mitchell, together with Slaters' wheel-sets. (The coupled wheel-sets were replaced with Slaters' ones, very early-on, following the discovery that the loco would drop between the rails of PECO Streamline track!!!!! It was a 'double whammy' on the part of the Alan Gibson wheel-sets, the axles too short, and the material employed for the wheel centres made the wheel, at the rims, excessively flexible.)

Here's a closer view of the cast parts to form the pony trucks:-


There's a fair bit of work just removing the casting excess.

Having removed all the excess casting material and offered-up the various parts, I came to realise that I needed a jig to aid assembly as, essentially, all the parts just butt together. I also fabricated a jig for opening-out the holes to 3/16th clearance for the Slaters axles. For info, using my jig to ensure the truck sides were square to the axle and aligned with one another, I first soldered the lower two stretcher rods in position. This made the two sides, whilst still mounted on an axle, sufficiently stable to solder in the place the cross-stretcher by just the front tabs. At this point the assembly was stiff enough to allow the top swing arms to be soldered; soldering these in place also solders the rear of the cross-stretcher to the sides. The assembly is now pretty solid, which is just as well considering the tweaking required to align the lower swing arm stiffeners. Here's the front pony truck freshly assembled and just needing a clean-up:-


From left: original truck and wheel-set; replacement truck; new wheel-set.

 
 

Here's two views of the replacement front pony truck, with its wheel-set, attached to the chassis.

        

Following some fairly successful test running, a final tweak was made to the rear pony truck's swing arm bearing, and the trucks and wheel-sets were spray-painted. At the time of reassembly (of the whole loco) I decided to replace the front brakes and their cross-stretcher with cast Brass versions.

And finally, two views of the revamped loco.