The slots have to be longer to give engagement with imperfect alignment, which is to be expected if an oldham coupling is being used.

I assume the taper on the tongues is to deal with angular alignment.

I have to ask, is this a particularly ill-built or flexible car?

Neil

Similar couplings were used on many budget-priced n-gauge locos in the 80's. They allow a degree of horizontal misalignment (not angular) as the brass (or in n-gauge locos nylon) centre is free to slide in the tongues machined on the driving and driven plates to take up the misalignment. The driving and driven tongues would normally be at 90 degrees to each other to permit this. Provided lubrication is maintained they would seem to have a relatively long life.

Maurice's mention of these couplings in teleprinters stirred an ancient memory. The fibre disc was designed to break (like a shear pin) in the hope of preventing damage should the mechanism jam. (Useful to know this when checking out a time-served teleprinter before buying it. )

Possibly the brass disk in the old car is protective?

Dave

Very many fuel injection pumps on Diesel engines were driven by a similar coupling with steel flanges driving onto, and by a Tufnol type material with four evenly spaced slots, to match the straight sided teeth. Despite the torsionals from the fuel pump coming one way, and the crankshaft torsionals coming via the timing gears, or chain, they used to last a long time.

More recently, this type was still being used to drive Jabsco Sea Water Pumps on marine engines

There was another type of coupling in which the steel elements had a "tooth"section similar to a knuckle thread, with a similar shape to the fibre or hard rubber insert. The clever ones had a difference of one tooth between the driving and driven sides, so as to allow a vernier adjustment for magneto timing.

Howard