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Standard Gauge Plymouth Shunter

The Plymouth shunter provides a good starting point for a rebuild into both standard and narrow gauge operations. It is also easy to modify for the larger scales (SM32). Added to its good looks and ease of kitbashing is its running ability. A small loco it is but a great runner is hidden underneath. Do not write this one off if you see it, no matter how bad the body is, there is a great mechanism lying in wait.

This article focuses on the changes required for a standard gauge version.

A little History
In 1987 Chris Ellis, and Malcolm Carllson each wrote an article, in the then Scale Model Trains, about a conversion for the Atlas Plymouth Shunter. The purpose: to make a cheap and easily completed conversion to get your O gauge layout running.

At the time I was going into O so I followed along and began the detailing project. Years come and go and all the while I have kept at my hobby (this loco so far was bought new in 1981, started in 1986, restarted in 1994, and is being finished in 2000, possibly the worlds longest modelling project). While Chris Ellis' original article contained some great ideas, there are several ways to make the little engine that could much better than described in the original article.

The overall design of the loco is squat. This lack of height causes it to not look right for the English loading gauge. While the American loading gauge is wider than that used in either England or Australia this models is in 1:48 (American O) so the outsized gauge does not cause a problem for us 7mm to the footers.

Updating the Model

The mechanism and electricals

As it stands the mechanism of the shunter is its best feature. Out of the box all four of my locomotives have run well. After a few hours of running-in they run even better. Slow speed crawling and even starting being their best attributes.

The first thing to do to begin this process is to disassemble the motor from the block, by removing the two screws in the base of the block. To get to them you have to remove the retaining plate for the wheels. this is held in place by six screws.

With the motor out, and all electrical connections removed set the motor in a safe place and remove the wheel sets. Store these also. Replace the keeper plate and reseat the six screws.

Onto the body

The most obvious issue for modellers of English or Australian prototype practice is the height of the body. This will consume a great deal of the project time and require the most Plastikard. Do not think that this is beyond you however. I have used where ever possible stock components available either from Evergreen or Slaters.

Next most important piece of body work concerns the style of the windows. These need to have the bars removed. This gives the loco a more appealing look about it and removes the toy-like look.

Finally we will tackle the unit's weight and motor block. As the largest casting in the model it is very invasive to the viewing eye and needs to be hidden. Hiding it from view is done in two phases as part of the other construction:

  1. Raising the height of the loco body, and
  2. Painting the cast weight/motor housing black. (This lowers its visibility to a minor nuisance. And I can live with that.)

 My First Loco
I followed Chris Ellis' directions pretty much to letter with basic build of this first loco.

  1. I cut through the bonnet of the loco, 5mm aft of the radiator and added a 6.7 millimeter fillet to increase the overall length of the hood. While this minimizes the front porch of the loco, for the purposes of this project, and the uses intended for this loco, it is not an issue.
  2. I rebuilt the front end to remove the light and Plymouth name. I did this because I wanted to have an inherently Plymouth design, but, reflect the rebuild by the current owner. Also since this loco is bound for use on a UK based private line in the late 1970's a headlight, of the Plymouth type, would have looked out of place.
  3. I rebuilt the cab backend to refocus the loco to a rearward facing shunter rather than a hood first unit. I did this because I did not like the expanse of flat space on the rear of the loco inherent in the previous articles. By refocusing the loco's layout to the rear, I also made the unit's look much more aggressive. Something I felt was needed to have on a tough little industrial diesel. A full article will cover the design and fitting of the backend structural work and one piece skin.
  4. Narrowed the Cab by sawing through the front and rear windows. Removing about 1.5mm. (I will not do this one again.)
  5. Shortened the footplate by 10mm at the rear. (In the process removing the air-tank.) This was suggested by several of the previous articles and I decided to follow this design for the first loco and see if I liked it. I found that in practice cutting 10mm from the length makes the loco look unbalanced. By leaving more of the loco you give the unit a more balanced, substantial, appearance.
  6. Rebuilt the cab to a more angular profile. Replaced the loco roof with one of my own design which updates the Loco to a more contemporary 1970s design.

Chris Ellis' suggestions while interesting do lead to some other issues that I will not repeat on the remaining three.  For the article on the full rebuild, with graphics, follow this link.

I am suggesting that these locos represent two different phases of locomotives. The one (my first) a rebuild, to bring it up to current operating standards, due to union and Occupational Health and Safety pressure. The remaining three represent the locomotives in their original guise before going to the works for a rebuild.

The next three locos

The redesign on the next three locos will be simpler and require less cutting and chopping, to reflect an original locomotive bought from the Plymouth company.

The following modifications were carried out on the first loco and will be standard modifications on the sister locos:

  1. Add 80 Thou to the height of the footplate. (This helps when you place the buffers onto the loco. Provides a much more stable surface for parts to stick to also.)
  2. Removed the bars from all windows. Enlarged the inner front cab windows and re-profiled them to follow the curve of the bonnet (hood). (See next point.)
  3. Removed the standard exhaust housing on the loco and installed a stove pipe chimney. This also provides the means to secure the body to the chassis. (More on this later.)

While the list above looks extensive it is not. The overall effect is very powerful though and gives you a highly detailed model for very little money. For the article on the less exacting rebuild, follow this link.

I added handmade detail parts, that were not on either of the articles I read in the magazine. They comprise hand-made angle-cocks and hoses. Bolt and rivet detail on the buffing plates and some after market material too:

  • Glad-hands,
  • Three link couplings (Alan Gibson), and
  • Working sprung buffers.

I am still debating the effectiveness of this level of detail for the remaining three loco's. However until the paint job is finished I do not know how much of this detail will be lost. I am considering it as it makes the locomotive look much more workman like.

The first unit is fitted with Air and vacuum Brakes. The piping on the front buffer beam is simpler than it would be for an American loco, but the level of detail looks right for its setting.


I am still considering the paint scheme. I am leaning toward a mid-blue body, grey roof and black running gear. Yellow ends and possible tiger stripes may be there too. Your thoughts would be welcome.


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