Hohner - Model IN20S Series - Incremental 2.0" Blind Hollow Shaft Encoder

Slide encoder onto shaft.  To keep encoder from rotating: have a pin to prevent rotation in one of the mounting holes, or a bracket bolted onto the mounting holes, or simply tie wrap the cable.  Whatever is done, ensure there is a bit of play between encoder and mounting arrangement to prevent bearing damage.  Hook up the encoder with the connections as described.  Make sure power supply meets specifications.