Hi-Q Coupling Half, 0.88 Inch Bore, 3/16 Inch Key

Coupling hydraulic pumps to electric motors is exactly what this part is built around. The Hi-Q half is machined cast iron, so it holds up well in industrial use, and it compensates for minor misalignments which is a real help when you're lining up a pump and motor in the field. Just keep in mind the angular offset tolerance is 1 degree and the parallel offset tops out at 0.015 inches, so your alignment still needs to be reasonably close before you button everything up.

This one matches a 0.875 inch (7/8) bore and a 3/16 inch key, so it lines up with a 7/8 shaft that uses a 3/16 key.