Sleeve shaft couplings or elastomeric donut couplings have their elastomeric elements in shear.  The type of coupling uses a rubber element with internal and external gear teeth that engage with mating teeth in the two shaft hubs.  The rubber element comes in one piece, one piece split, two piece split with a steel locking ring that fits into a groove in the rubber. These couplings accommodate 1 degree of shaft misalignment while dampening shock and vibration.