The Steamboating Forum

It seems that my 6A has quite a lot of play in the crosshead guides. Is this normal or what should it be? I have 0.006" on the HP and 0.010" on the LP.
Gudmund

Gudmund,

You should be about 0.002" with this type but that's assuming things are lined up properly and the wear is even, it would probably be better to strip down and check to see if the guide faces need re-machining. The trouble with the 6A and many other brit machines is that they are too short in the conn rod length leading to high crosshead forces.

regards
Jack

steamboatjack wrote:Gudmund,

You should be about 0.002" with this type but that's assuming things are lined up properly and the wear is even, it would probably be better to strip down and check to see if the guide faces need re-machining. The trouble with the 6A and many other brit machines is that they are too short in the conn rod length leading to high crosshead forces.

regards
Jack

Yep! It's called angularity and not only does it cause greater wear, but the angle the conn rod makes with the piston travel also creates some really great discrepancies in % of piston travel as compared to % of crankshaft rotation. One reason why a "loping" motion is greatly accented in the short conn rod engines. Engine designers of 100+ years ago made their connectly rods as long as FEASIBLY possible. Makes for a "long legged" engine that runs VERY smoothly.