Tag Archives: Denis Bates

Converting the Murphy-Bachmann 141 Class Diesel to 21mm Gauge

Denis Bates

 

The General Motors 141 Class diesel of CIE was introduced in 1962, and for over 40 years has been among the most successful of the Irish diesels.  So it was not by accident that Murphy Models chose it for their first foray into a completely designed Irish model (the previous Woolwich Mogul and the NCC Jinty were of course repainted versions of the English models).  So, although my main interests are in steam days, and particularly the BCDR, I couldn’t resist purchasing one, with a view to re-wheeling it to 21mm gauge and P4 standards.  The prototype is described and drawn in two of the model magazines: by Tim Cramer in Model Railways for March 1977, and by Shane McQuillan in Practical Model Railways for June 1986. The latter article describes also the building of one, from a kit by the Model Irish Railways group. Comparing the Murphy model with the drawings, I could find nothing amiss – except for the buffer spacing. The buffer centres should be at a spacing of 6’3”; on the model they are at 23mm (5’9”). I presume that is to match the spacing of other Murphy-Bachmann models, at English spacing.

I first determined that a P4 wheelset would fit between the bogie frames, and it does, just. My main mistake was to dismantle the loco as far as possible – this is not necessary, as the bogie frames can be levered off. They are similar to those of the Bachmann Class 20 diesel (described by Keith Norgrove at http://www.norgrove.me.uk/index.htm). A screwdriver is used to prise out the frames, which appear to be identical on the two bogies. The wheelsets can then be prised out of the bogies. Each wheelset has an offset plastic gear wheel, two brass bearings which are a push fit in the sideframes, and brass wheels with insulating sleeves. Measure the distance of the gear from the ends of the axles, before tapping out the wheels and sleeves using a small drift and hammer. The gear wheel can similarly be tapped off the axle.

If the model is to be converted to EM gauge, all that is necessary is to cut 2mm steel rod to the appropriate length, and put the gear and wheels on. Although there is a spline on the original axle for the gear, it seems tight enough on a plain rod (a smear of loctite could be used to anchor it firmly). To keep the axle laterally in place, two brass sleeves, or an appropriate number of washers, should be added between the gear and the bearings (or between the bearings and the insulating sleeves (see figure). For conversion to P4 and 21mm, the original brass wheels can be used, but have to be turned down to receive P4 rims (these are obtainable from Alan Gibson on special order). It is also possible to turn down the existing rims to P4 standards. For those without a lathe, it may be possible to purchase P4 wheels to suit. Before finally inserting the wheel sets, the pickups need to be adjusted so that they bear on the backs of the wheels. On the Bachmann wheelsets, the hub projects further out than the rim, and does not fit easily between the sideframes. However, the insides of the frames can be filed out (about 0.5mm or more) to give clearance. I used a cylindrical dental burr to do this, held in a drill press, and hand held the frames. Once finished, the loco ran just as well as it had done on 00 track. Now to try it on Adavoyle Junction, out of period though it be!

3 Comments

Filed under Modelling

Building BCDR Diesel No. 2

Denis Bates

 

No. 2 at Ballynahinch (Denis Bates Collection)
No. 2 at Ballynahinch (Denis Bates Collection)
No. 2 at Ballynahinch (Denis Bates Collection)
No. 2 at Ballynahinch (Denis Bates Collection)

When travelling from Dundrum to Belfast in the 1940s, a journey I often did, one of the sights on the journey was of the Ballynahinch branch train. Although sometimes the branch engine was 2-4-0 No.6, more often it was No.2, the Harland and Wolff diesel electric loco of 1933. Looking like a Co, it was in fact a 1B: the front axle was un-powered, and the other two axles motored. Harland and Wolff tried, with a little success, to break into the diesel market in the 1930’s, supplying engines to the LMS. A diesel shunter was supplied to the NCC, and a Bo-Bo, No.28, to the BCDR.  No.2 (originally numbered D1) was their first diesel electric locomotive, and was described in some detail in The Locomotive (June 15th 1933) and The Oil Engine (May 1933) from which the general arrangement drawing is taken.  The engine was rated at 270hp, and could haul 200 tons up a gradient of 1:100 at 16mph. On the BCDR it spent most of its life on the Ballynahinch branch. As it could not provide steam heating, a set of carriages was modified to provide electric heating. On the closure of BCDR’s main line in 1950, it was sent, together with brake carriage, to provide a short lived service between Newcastle and Castlewellan. It travelled south on Sunday 14th January 1950, illustrated in RM Arnold’s book at Crossgar. I recorded it at Dundrum – it must have travelled via Downpatrick station rather than the Loop Line, as it was cab first at Crossgar, and bonnet first at Dundrum.. Eventually it was returned to Harland and Wolff, and was used by them as a shunter in the shipyards.

No. 2 in what appears to be mint condition (Denis Bates Collection)
No. 2 in what appears to be mint condition (Denis Bates Collection)
No. 2 at Dundrum (Denis Bates Collection)

No. 2 at Dundrum (Denis Bates Collection)

The Model: Chassis
When buying Athearn diesel parts for building my Turfburner model (New Irish Lines…), I measured a number of Athearn diesels. I found that the bogie wheelbases of loco PA-1 were the same as those for No.2. This led me to buy an extra bogie. In addition, a set of gears made by the Ernst Manufacturing Co, of Oregon (listed in Walther’s catalogue) enabled the gear reduction to be increased.
Chassis

Chassis

At the time of writing, this loco is not listed in the current Athearn listings, so may be out of production. As with the Turfburner, wheelsets were made up using the Athearn axle muffs, turning stub axles and wheel centres, in conjunction with P4 wheel rims supplied by Alan Gibson. A small Mashima motor and a turned flywheel were mounted on top of the bogie, driving the original Athearn worm wheel and hence the drive train. Leads from the motor were soldered to the chassis side frames, and off the mechanism went. For P4 standards, the centre axle cut outs were filed slightly high to allow the axle more vertical play. The rest of the chassis is composed of the dummy outside frames, buffer beams and footplate. The most distinctive features are the Isothermos axle boxes. These were turned on the lathe, and added to the spring units: I think I trawled through catalogues to find tender springs/axle boxes which seemed closest in appearance. Sprung buffers were again turned.

 

 

Body
Body

 

 

 

 

 

Body
Body

I originally thought to make the body myself, but eventually asked Joe Magill, who has made some beautiful models of Irish prototypes in both 4 and 7mm scales, to make it for me – so the striking appearance is his. The distinctive louvres were etched to order by Bill Bedford, to artwork that I drew (they now appear in his pricelist). The paintwork is again by Joe Magill.

So No.2 is ready to enter service, when I get some track laid. Baseboards have already been made, and at the moment the thoughts are of the Ardglass branch – either the very simple Ballynoe station, or Ardglass itself, with its turntable and extension to the quay. Ballynoe station still has its full complement of buildings; Ardglass in 2004 had the goods shed, and a very derelict but complete station building.

 

 

The Model: Body

 

 

9 Comments

Filed under Modelling