sq4 Coupling gear play

[Henning G]

Hi, does anyone know how much play there is acceptable in the SQ4 coupling gears

[allan.walker]

An interesting question!
I'm sorry that I can't offer any specific advice on this, but I do wonder that if the play is not acceptable, what can be done about it?
Both of my Square Fours have some play in the meshing of the coupling gears, but I just live with it.

Someone else will be along with a more helpful answer to your query, I'm sure.

[Paul_Linden]

There should be no play on the gears on their shafts [obviously].
There might be a very small amount of play between the teeth of the gears.
If I recall correctly, the coupling gears were paired at the factory for balance and play, and should have matching numbers on them. Is it possible you have a mismatched pair?

[JohnnyBeckett]

hi the only way to fix it if it got too much play is to get a new pair made , or try and find someone who has got a good pair for sale but i think they will be hard to find good a good pair i don't think metal spraying to build up the teeth will work for long

[Henning G]

Hi, Thanks a lot for your great replays. Correct, not much can be done about it, but mine had a play between the teeth of 0,01”. That made noise, found a pair with 0,004, but not sure if that’s ok..