Tom Tom


Joining the Elmtree Line in the later weeks of 2016 Merlin’s model is a fair representation of this attractive prototype. It has some unusual and innovative features.

This engine was designed by Colin Cooper, son of Tom.


The body of the locomotive, including smokebox, side tanks, and cab, lifts off the working chassis as a single unit, being held in place only by gravity. This engine is radio controlled, as were all of Merlin’s engines of this type.


The electronics and batteries are carried in the right side tank. The large butane tank is housed in the left.


As with most R/C locomotives, this one uses two channels – one for the throttle and one for reversing. The reversing servo is near the front on the left side tank. A linkage connects it to a lever that moves the radius rod.


The servo controlling the throttle is opposite it on the right side. This is connected to the throttle via a very long arm that extends over the electronics compartment.


This example (built in 1981/2) is fitted with a pressure gauge and safety valve. Others had water glasses (there were several changes and modifications done at the factory over the production life of this engine). The throttle is unusual for a couple of reasons. One is that it is integral with the lubricator.


Another is that it does not employ a needle valve to control the steam. Instead, it has a rotating plate with holes in it that, when the throttle is open, aligns with holes in the throttle body. When closed, the plate rotates so that the holes are not in alignment, blocking the steam passages.


The chassis is fairly straightforward. The engine shown here is an earlier example that was made with remaining Beck piston-valve cylinders, which the company had acquired in 1981 when Beck went out of business.


Valve gear is dummy Walschaerts. Drive wheels are regaugeable, but the lead and trailing bogies have to be replaced if the gauge is to be changed.


The detail level is relatively low. Prototype photos show a variety of details (on various engines) that might be incorporated into this model. These include a double, “tropical” roof and strap-iron pilots on both ends.


Pictures to the right show as arriving at the Elmtree Line.


Pictures Underneath show after a trip through the workshops and in service.....