Whats this part called?

[devon TWiG]

24 minutes ago, Con said:

Any one with bikes will know it as a cush drive. Absorbs the shock from changes in speed

yep , most motorbikes ( but not all ) have them in the rear wheel , reduces snatch in the system , particularly chain / sprockets ...

[Dan Maynard]

Also to accommodate any slight misalignment between the engine and pump shafts.

[roys]

In industry we called them spider couplings, usually between electric motors and gearbox’s, noted I am not the first to mention spider coupling on this thread.

[spudulike]

Engineers will know them as "Doofers"!