DRIVING TROLLEY PLUS
by David Brownlow

HAVING recently read articles about electric pumps for miniature steam locos it may be of interest to comment on some versions I have built.  Cross Creek Railway Society at Featherston have a 7½”G loco purely for revenue running and a reliable backup water feed to cover the injector and hand pump was required.  The late Trevor Amos of KMR showed me a 12 volt spray pump obtained from Canada.  On viewing the website various sizes were available and I settled for a 200psi pump. Three of these were purchased for Max Kempson and myself as good backup arrangements for our locos.  

The photographs show the three compartments in the wagon housing the pump, 11 litre plastic water tank, and a deep cycle 26 ampere hour battery.  Drain holes are provided in the sealed water compartment. A push button on the front of the wagon operates the electric pump through a circuit breaker in the battery compartment.

Filling arrangements varied but on my wagon the cap incorporates a swan neck breather which served as a handle.  There is a supply water filter and a drain on the tank.  

The pumps have two inlet and two outlet connections allowing an easy application of an air bottle as a damper which improves the operation, particularly when sharing a clack valve as on the Fairlie.  An additional check valve was fitted on the locos at the headstock to protect the electric pump. For this I used a standard refrigeration non return valve at the rear of the loco and the connecting hose to the trolley is a refrigeration pressure hose with screw fittings as I have easy access to these.

The layout is neat and simple with much reserve in the battery as the pump is only on for seconds at a time.  It is also an easy way to fill the boiler at light up.  

The battery charger is a plug and socket arrangement and the battery is used for the light up fan, cab lighting, and the headlight.  All the wagons built have common plugs and sockets.  

The wagon on 5” gauge differs in that it has a smaller electric pump as a simple transfer arrangement feeding to the loco tanks only.

The wagons have been trouble free in use for over four years.  As the Fairlie has a reliable injector and a steam pump, the axle pump has actually been removed, and the electric pump is not used much, but it gives peace of mind should a problem occur.

This article first appeared in Blast Pipe, November 2011, the magazine of the Hutt Valley Model Engineering Society and the Maidstone Model Engineering Society, in New Zealand.

Photos by Peter Anderson.