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Double Tangye Steam Engine

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Jo:
The Edgar Westbury Double Tangye “Type” Mill Engine builds upon an earlier design by William Ballantyne published in Model Engineer in 1933. The original engine was a single cylinder design and casting sets for it have been know to appear on Fleabay. Edgar Westbury chose to double up the engine to make a “double”, that is two equal diameter cylinders rather than a compound which has different diameter cylinders in which the steam being first used in the smaller diameter “High Pressure” Cylinder and subsequently further expanded in the “Low Pressure” Cylinder.

The original type of engines upon which it was based was produced by Tangye around the turn of the century, although it should be noted that Westbury was unable to get any information from Tangye to support his redesign. His design was for a double engine which consisted of two complete engines sharing a common crankshaft. Both engines arranged right/left handed were mirrors of each other with independent valve gear, governor and throttle. The idea being that it represented a type of engine that you could make the engine up as either a left hand or right hand engine as single handed engines. But with a double engine with readily accessible working parts it could have been possible to disconnected one of the crankhead bearings and eccentric strap and run the remaining engine as a single providing better economy on light loads.

But as mention Edgar Westbury did not actually get any evidence from Tangye’s that they ever built such engines or that if they did anyone actually disconnected the second engine. The Westbury design published in 1953 originally showed a single Watts governor on one of the engines. If a single engine was always the one that was disconnected then this is adequate but subsequently in the series of articles for some strange reason the idea of putting on two governors came about. Hence many of the models you will see today have two watts governors fitted:



Technically Tangye’s about this time were always fitted with Pickering governors and records show that even on double engines a single  :ThumbsUp: Pickering Governor was used to control both engines.

When Westbury designed this engine he took the opportunity of reusing an existing model engine flywheel that was readily available. To date I have been unable to find any Tangyes that have a flywheel similar to the one he chose, their engines had a much simpler flywheel design.

So this build is going to take a standard design seek to make a model that is more like the original engines made by the Tangye factory and as for the colour.. :shrug:.. most are black.

Jo

Jasonb:
So you are not tempted to make it a compound rather than Double high?  :mischief:

J

Jo:
No twins have their advantages as well ;) I have seen the compound that was published in ME a few years back and it is not for me. Most of these engines went out to the colonies and for their use smoothness of running was desirable but an increase in pressure was not. Operating your boiler on what ever sugar cane remains was kicking around was never going to generate the same amount of heat as best Welsh steam coal which was too expensive to ship out. So most of these engines made do operating on lower pressures, so I question if whilst they were built as compounds if they really operated as compounds. I have seen engravings of Tangye doubles  ;)

My starting point for this engine is a set of castings that have been partially started by a "toolmaker" and his mate as for who did what: lets say there are some opportunities for correcting what has been done  :lolb: . I have been having a think:



Jo

b.lindsey:
Very nice engine Jo. Looks like they left you plenty to do too :)

Bill

steamer:
Nice looking engine Jo!   Looking forward to it!

Dave

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