Peter Nutbrown describes the resurrection of a unique Roundhouse 0-6-2


You know how it goes; your fascination is tweaked by a word in your ear when you are standing looking at a table of items for sale. You never intended to make a purchase but there is a glimmer of possibilities with a box of what looks like Roundhouse items. It’s a dark green body with a chassis and a boiler, you are hooked and the sale is agreed.

On returning home with this box of bits you think, not another kit to make in the dark hours of winter, put it in the cupboard with several other unmade projects and half completed disasters and those awaiting inspiration or a trip to the bank. Fortunately, you promised to assemble a running loco from these pieces and so it becomes the next to do project.

The box of bits was emptied onto the table to assess the contents and a list of parts made for the completion of a loco. It’s surprisingly long and unfortunately requires a visit to Roundhouse or a very lengthy period in the garage at the lathe and vice. The decision is made, test the boiler, that’s fine at 80 PSI though there is a small ding at the 10 o’clock position port side front. The flame shield was assembled from the etched pieces and the meths burner fitted with wicks. The boiler was fitted with a safety valve, pressure gauge and outlet valve and the arrangement was mounted on blocks.  The burners were lit and the flames enveloped the boiler, some severe wick trimming was required. Nothing could be achieved and the flames continued to appear just above the boiler, not a good sight. The decision to make it gas fired for safety was made which was a shame but the only practical solution.

The list of components had now grown to include a gas burner system and so list for a quick fix was taken to Roundhouse where one of the engineers scrutinised the chassis and agreed that they had never made an 0-6-2 Lady Ann but it had been modified by persons unknown  as the file marks were evidence of a butcher. He thought that the chassis had been made for an inside operated valve gear Lady Ann as there were pivot lugs on the chassis. Aside, this butcher now had to increase the cut out to accept the preferred wheels. Armed with six wheels, axles, cylinders and valve gear I returned home in the knowledge that something would quickly arise from that box of bits.

The chassis was stripped down, cleaned and painted and the wheels, cylinders and running gear fitted as per the usual Roundhouse instructions. The assembly was mounted on blocks and tested on compressed air with much lubrication and the valve timing adjusted.

A pony assembly was made up from a pair of 25mm diameter IP engineering wheels from the scrap box and half bearings from pins of a 13A plug.

A small lubricator was made and located next to the gas tank, then it was the turn of the “superheater” pipe to be somehow wound into the space below the boiler. After 3 attempts a plausible route was achieved, fitting within the diffuser and around the burner.

The flame diffuser was much modified at the forward end as it was made for inside valve gear. Larger cut outs were required for the actuator rod and a small flame baffle was made to protect the motion from radiant heat. A poker style burner was made from stainless steel which fitted neatly in the holes for the original meths burner diffuser unit. The frame spacer which supports the rear boiler mounting screw was modified with a stud and a cut out below to accept the burner.

A small gas tank from the spares box was located on the RHS of the cab and a gas pipe and nozzle holder made to pipe the gas to the burner. Trial run of the poker burner was a failure with too much primary air blowing the flame towards the final apertures and starving 50% of the burner apertures. A second burner was made and a row of 15 X 1.5mm apertures with 2 X 1.5mm primary air holes. This was fired up on a steel tray in a jig and the flames were bright yellow tipped, a carburising flame and 50mm high indicating insufficient primary air. The primary air apertures were increased to 2mm and the flames were burning bluish but still with yellow tips about 30mm high. The number of burner holes was increased to 30 with additional holes either side of the centre line midway along the poker. This modification lowered the height to 10 to 20mm high of the flame but with some yellowing at the tips. Finally, 2 extra 1.5mm primary holes were made and the resulting flame was a good all blue colour, indicating a neutral flame had been achieved, this was accompanied by a pleasing low roar, success at last.

Now to painting. I plumped for BLACK in varying shades. The boiler and diffuser were spray painted in Bar-b-que heat resistant paint, the chassis received a matt satin spray and the bodywork and smokebox black gloss; oh and a splash of cream for the cab back head.

The bodywork was assembled, lamp irons fitted front and rear with rivets and a real coal load placed in the rear bunker, cast tank fillers were mounted and all was ready.

The usual oiling, watering and gassing up regime was followed for a Roundhouse loco which was then placed on my indoor layout. Within 8 minutes of igniting the burner from above the boiler the pressure gauge commenced to rise. At 20 PSI I engaged forwards and opened the throttle, nothing. Impatience had got the better of me so I shut the throttle and waited until the safety valve lifted at 30 PSI. This time the loco set off at an alarming pace throwing condensate out of the funnel for half a lap, obviously too much water in the boiler. Two loaded bogie wagons were coupled up after the 1st. lap and the loco happily pulled this load of about 2Kgs. For the next 15 minutes until the gas ran out, after all it is a small tank. The safety valve was removed from the boiler and reset at 40 PSI.

The second run was conducted more smoothly, the gas pressure was reduced to a minimum. This time 50ml. instead of 20ml of water was removed from the full boiler of 275ml prior to firing. A nice sedate run of 20 minutes was achieved but still with some expelled water on start up. I now look forward to running this manual external fired loco in the garden this summer and it might even get a mock steam dome and sanding gear with some boiler bands to hide that annoying ding on the boiler!

Peter Nutbrown June 2019
































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