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Engine mounting

How best to fix down a steam engine

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michael howarth 116/07/2020 07:53:02
34 forum posts
4 photos

On testing my Vospers, fitted with a steam engine, I was forced to review how the engine is "tied down". The link between the 2 cylinder engine and the propshaft is via a universal coupling.... one of those red plastic types. With the engine bolted down firmly there is a significant sort of clicking "knock". This is obviously an alignment problem as the knock disappears if the rear of the engine is raised by about 5mm and I then get smooth running. Experimentally, I have placed a pad of dense foam under the rear of the engine which seems to have the effect of absorbing some vibration. Is this the way to go or should I go for a rigid fixing?


Edited By michael howarth 1 on 16/07/2020 07:53:46

Malcolm Frary16/07/2020 09:31:33
995 forum posts

If it is a single joint, alignment needs to be, and stay, perfect. That means having the center lines of the motor and prop shaft intersect at the center of the universal's spider. Anywhere else, something will be trying to realign itself, giving a repeating clonk. A resilient mount might reduce that, but will leave the motor constantly trying to realign itself. Anybodys guess how long before you find out what the weakest point of the mounting is.

A better answer would be to use a double universal or a rubber coupler or a dogbone type.

Ray Wood 216/07/2020 10:10:41
2357 forum posts
829 photos

Hi Mick,

Lots of full-size engineering alignment is based on using shims, aluminum packers would work to loose the knocking ??

Regards Ray

David Marks 116/07/2020 13:08:20
255 forum posts
44 photos

The red plastic coupling (trade name Huco) should be set up so that both halves are on a common axis. To do this I replace the plastic piece with a dummy body (made from aluminium bar) of the same length and bore size so that it accepts the two brass inserts. Once alignment is achieved the dummy body is replaced by the red plastic section.

michael howarth 116/07/2020 20:52:36
34 forum posts
4 photos

Thank you gents for the valuable advice. Why didn't I think of that alignment method?


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