Progress on John Heald's B-class

The valve gear is completed and spot on in both forward and reverse.

On the full sized engine the motion link eccentric pivot hole centre is directly in line between the piston rod centre and rear axle centre, thus giving what is called a perfect square layout for this type of valve gear. The model in 4" scale turned out to be the same but there was no way I could set valves until back set was built into the link. This was a major problem for Ray McMahon who had the same problem on his 3.5" model and he developed his back set by trial and error until he got equal valve travel in all gears. He stated this in his latest Model Engineer magazine article I got last week.

Just doing final fitting work to the running boards and setting up the position of the mechanical lubricator that will sit in the same position as per Sharp Stewart drawings, although I think I may take the drive off the motion link top or eccentric rod end.

I am working on the boiler fittings now and have the regulator installed with cleading to be done next week and with luck boiler on frames by mid June.

The the easy parts!!!

Just a few shots of the regulater. Its a 1/2" ball valve. The small 3/8" elbow is for the steam supply to the Manifold and will be held in place by a bracket to the 1/4" stud on the regulator face plate. It took me two days to figure out how to get the steam supply from the dome to the steam manifold!!!

Words and photos by John Heald

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Website developed and maintained by John Oxlade of john2consulting who is a member of the Cambridge-Rotorua Live Steamers Inc.