Hi-Q Coupling Half, 0.75 Inch Bore, 3/16 Inch Key

that bore size lines up exactly. The FC100-3/4 is built for 3/4 inch shafts with a 3/16 inch keyway, and coupling hydraulic pumps to electric motors is pretty much the textbook use case for this whole product line. Just make sure your mating coupling half matches up, and keep in mind it'll handle up to 1 degree of angular misalignment and 0.015 inches of parallel offset, so your alignment doesn't have to be perfect but it shouldn't be sloppy either.

Designed for coupling hydraulic pumps to electric motors, this Hi-Q coupling half can definitely be used in a variety of other applications, too.

The bore on this coupling half is 0.75 inch and it uses a 3/16 inch key, so it matches a 3/4 inch shaft with a 3/16 keyway.

Connecting hydraulic pumps to electric motors is exactly what it's built for, though it handles plenty of other shaft-to-shaft applications just fine. The bore is 0.75 inches with a 3/16 inch key, so as long as your shaft matches up, you're in good shape. It also tolerates minor angular and parallel misalignments, up to 1 degree angular and 0.015 inches parallel, which takes some of the headache out of lining things up perfectly every time.