It's fair to say things have moved on since I made my first tentative steps towards a Proto 87 layout in late 1998. The only option then was the steel axle and tyred Alan Gibson wheelsets. But early 1999 saw NWSL come on stream with non-magnetic wheelsets and thus opened up P87 to the joys of Kadee type couplers. Soon afterwards NWSL half axles were available which made conversion of Athearn and LifeLike diesels a thirty minute doddle. But still there remained the question of re-wheeling a steam locomotive, never the easiest job in any scale but in P87 something of a leap in the dark

 

This is an account of the conversion to Proto87 of 'Federal Street's' first steam outline locomotive, a Pennsylvania Railroad A5s 0-4-0 Switcher. 'Federal Street' is a small switching layout being constructed to P87 track and wheel standards. The layout follows Pennsylvania Railroad practice c. 1948 to 52 and is based on the Whitehall Branch in Southside Pittsburgh on the Pennsy's Monongahela Division. The branch had street running and several spurs which wound their way in and out of various industrial locations.

It is not an account for the purist as it uses P4 Sharman driving wheels which, apart from not being correct for the A5, have a slightly overscale tyre width and flange. Also, in order not to overcomplicate matters, no attempt has been made to reduce the width of the tender trucks. Rather it was seen an exercise in getting a steam outline locomotive running on the layout and to see what problems might be encountered. The A5 was chosen as it seemed, on paper at least, to offer few problems in this my first conversion. And so it proved. Plenty are around on the secondhand market, too. In the light of all the many things considered during the construction of a layout it is debatable if any further alterations to the model will be made.

Prototype Info

The Pennsy's A5s* switchers might come as a bit of shock to those used to our Barclay's, Hawthorns and co. here in the UK.. The A5s was a class of 47 locos built at Altoona between 1916 and 1924 for work on tightly curved tracks on the system. Most worked in the eastern section of the PRR ...... New Jersey, New York, Philadelphia. But as 'Federal St'. is set in Pittsburgh I have had to resort to 'modeller's licence' and assume the loco is on trial on the Whitehall Branch for such a short period the composers of historical records failed to notice.

Cylinders 20" x 24" / Drivers 4' 2" (dia) / Pressure 185 psi / Grate Area 38.3 sq.ft. / Superheating Surface 219 sq. ft. / Weight (eng. & tender) 131,750 lb. / Tractive Force 30,190 lb.

As these 'tiny' locos had a wheelbase of only 7ft 3 ins they must have ridden like the proverbial bouncing cork!

* The 's' suffix denoted a superheated loco on the PRR

Parts List

1 x Sunset HO A5s PRR 0-4-0 Switcher ( Prestige Series)

4 x Sharman 14mm driving wheels ( Millimeter Range ) Code M426

1 x Pack of Puffers Flexichas Hornblocks ( for 1/8 ins axles ) Code CG001 & CG002

1 x NorthWest Short Line 28:1 ratio Idler Gearbox (for 1/8 ins axles) Code 142-6

2 x NorthWest Short Line "Wimpy" HO loco driver springs Code 1400-4

1 x NorthWest Short Line Universal Coupler Set (for 2.0mm & 2.4mm shafts) Code 482-6

1 x NorthWest Short Line 33 ins P87 wheelsets ( pack of 4 ) Code 37617-4

Plus a selection of hand-tools, needle files, soldering iron, epoxy resin (Araldite) etc.

 

Proto87 Conversion Method

From the outset I didn't want to alter any parts that would stop the loco being returned to its standard HO form so that ruled out re-profiling driving wheels and dis-assembling the original gearbox. Not using the original drivers meant that I would have to provide not only new drivers but also a set of axleboxes to match the rectangular cut-outs in the frames. Being a lazy so and so has definite advantages as my first reaction was to look through the 'junk' box to see if there was anything there that would do the biz. And the Puffers hornblock set were an almost exact match. I think it's fair to say that the main focus of the conversion centres around these parts. There are other makes of axle boxes but I haven't tried them, nor can I vouch for the hornblock cut-outs being the same dimensions in other brass locos. Any feedback here will be appreciated.


The Puffers Flexichas etching and hornblocks

The loco drivers and motion were removed and the Puffers axlebox guides soldered up. A triangular needle file was used to thin the hornblock guides until they were a comfortable fit in each hornblock cutouts. At this point I was assuming that the substitution of the Puffers units would match the centres of the wheels and as it turned out it did..... phew! The hornblocks themselves were tight for the Sharman Wheels axle and needed an 1/8 ins reamer. The guide units were then cemented in place with a smear of Araldite and left overnight to set.

Hornblocks in place on the chassis. The LHS hornblock has been turned around to show to the camera the small bracket that had to be soldered onto each one to take the small coiled springs used in American brass loco suspension.

In order to make use of the coiled spring suspension as found almost universally in Japanese and Korean brass locos a small bracket made from brass angle had to be soldered to the top of each hornblock. If a thicker hornblock was available this wouldn't have been necessary. The original springs were left in the front hornblocks as this wheelset wasn't to be allowed much movement. NWSL "wimpy" springs were substituted at the rear. The hornblock guides on the outside of the loco frames were seen to be slightly proud of the hornblocks and the opportunity was taken at this stage to file them flush. This action would stop any edges catching on the insides of the driving wheels.

Ventral view of the frames showing the new crankpins made for the driving wheels and the removal of plastic at the bottom of the gearbox for clearance purposes.

A couple of concerns with the Sharman Wheels were encountered during the conversion. The driving wheel crankpins were too small for the A5's rods and Walshaerts eccentric crank so new ones had to be fabricated. As the Sharman Wheels' crankpin is moulded into the wheel and I did not want to risk cutting it out, I used small brass tubing (about 1.5mm dia) which was Araldited in place around the original. These new crankpins were slightly coned at the ends with a needle file to give a good force fit with the eccentric. The coupled wheels' crankpins were used as is. For these, the brass bushes supplied with the wheels were carefully filed down to just clear the bearing hole recess in the coupling rod. The hexagonal nuts were rounded to shape by placing both together on a 12BA bolt, held in a pin vice, and filing until they fitted with clearance into the coupling rod recess.

On inspection I felt I needed to reduce the thickness of the metal at the rear of the flange to get it closer to the P87 profile. Looking for the easy option again, I decided to carry this out by hand using a needle file. But this turned out to be time consuming. On reflection I should have made an arbor for the wheels and gently skimmed them on the lathe. The gearwheel was then tapped carefully into place on an axle then the wheels put in place and quartered. I'm happy to do this by eye but a jig might be a better bet for some. A drop of Loctite or similar is recommended as I have known wheels such as these to slip out of alignment. The gearbox had to have a lot of plastic removed around the gear wheel to get the required ground clearance. This has exposed the gear but shouldn't be a problem.

I've never been keen on wiper pick-ups but de-insulating the Sharman Wheels (or any plastic centred wheels for that matter) always needs care. A 36 SWG copper wire was soldered (be careful) to the inside of the tyre and wound once around the axle, keeping the wire tight, and soldered to the opposite side of the tyre. Then the wire was snipped off and filed down at the solder so that it didn't affect the back to back at the rear of the flange. There is enough tyre thickness to take solder but please be careful, the application of the iron has to be precise and quick. My advice is to practice on an old wheel first if you are not confident. Years ago I explained this method to Mike Sharman. He's speaking to me now, but I can understand him not wanting to recommend it. Pools of melted plastic and angry letters come to mind.

NWSL idler gearbox, Universal couplings and steady bar attached to the Mashima 18/33 motor. Balance weights have been added to the wheels.

The gearbox needs to be constrained otherwise the loco will wobble all over the place when running (if it runs at all). This was carried out using a steady bar fabricated from 20 thou brass attached with 12BA scews tapped into the top of the gearbox. The other end was soldered to the motor's mounting plate ( see photo above ). NWSL universal couplers were fitted on each end of the two shafts which were carefully cut to length using a carborundum disc in a mini drill. Take care with this as it's easy to make the setup too tight or too slack. Aim for about 1mm free play. I don't care to use the Sunset's plastic tube to connect motor to gearbox when the distance between them is so short. Unless there's perfect alignment it can lead to nasty things like vibration and over-heating.


Ready to roll

Finally the motion was re-assembled and the Walshaerts eccentric cranks aligned and carefully soldered into place. Most brass locos I have come across have a screw for tightening these but not so this model. It is a nuisance when stripping a loco down.
The tender uses NWSL Proto87 33ins wheelsets which are insulated on one side only and are thus ideal for the job. A small amount of vertical play was introduced at each pin point with a fine pointed stone in the mini drill again. I have found it a very desirable feature to have independent vertical movement of each wheel in Proto87. Just relying on the rocking movement of the trucks is not sufficient to hold the track reliably.

And that's it. I'm very pleased with the running of the A5. The electromagnets in use on Federal Street require very precise control of the locos and it has proven as good as my two P87 diesel loco when switching. All can crawl at the slowest possible speed which you need when working with Kadee couplers. As much lead as possible has been added and still have the centre of gravity between the coupled wheels. Pulling power is only around 30 grams but it's easily enough to lug half a dozen heavily weighted freight cars around the layout.

Useful Addresses ( Thanks to Russ Elliott for recent updates )

Finally my thanks to folks on the PRR and Proto 87 lists for their assistance and support. The internet is bringing us all together and that can only be for the good of the hobby.

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© John H.Wright February 2000