hi carl,

is your version the slide valve or piston valve version?

both use the same valve gear despite martin evans' misunderstanding the use of launch links with direct drive for slide valves (outside admission). the slide valve valve gear version is defective, as requires a considerable suspension offset where the bottom of the lifting links joins with the expansion link which isnt as per the drawings.

cheers,

julian

Hi Chris,

You will not find the angles of advance for the eccentrics on the Torquay Manor drawings because Martin Evans did not know how to work this out.

With Stephensons valve gear there is an optimum setting of the eccentrics for best valve events.

You can these days work all this out accurately and quickly on a computer on a valve gear simulator such as Prof Bill Hall's. Or you work everything out mathematically using Don Ashton's book.

Or you can guess the angle of advance by laborious minor alterations at certain cut offs and noting the amount of lead at Front Dead Centre (FDC), and Back Dead Centre (BDC).

On a piston valve loco I would use the cylinder drain cocks to find out when the valve opens to steam, checking first that the drain cock holes are not obscured by the piston at the end of it's strokes.

The GWR Churchward Stephensons valve gear uses relatively short eccentric rods which causes lead to increase far more as the gear is notched up when compared with other arrangements.

Therefore your Manor should be set for the valves to provide negative lead in full gear cut off of say 79%. A good starting point would be negative lead of 10 thou in full gear. This will result in lead not being excessive when the gear is notched up.

Each time you alter one eccentric or both the valve will need centralising again to produce equal leads – which is rather time consuming on a piston valve loco.

FDC and BDC must be accurately established and not guessed at.

Cheers,

Julian