Gerald, Do you think that the Grub screw (which came along with the Orient motor package) would be sufficient to provide a secure connection between the motor shaft and the pinoin. Do we need to have a key inserted as well.

You should have a pair of grub-screws (2) in each pinion, 90 degrees apart. We have tightened ours once only (really tight), and added Loc-Tite, and they have not come loose.

A keyway is not recommended. They have a habit of developing a slight loose movement with frequent reversing of direction.