Alternatively, the shaft could be provided with a plurality of {HEAD ~ keys} or {TAIL ~ keyslots}, and the disc 51 provided with a single keyslot or slot engaging member 
Alternatively , the shaft could be provided with a plurality of { HEAD ~ keys } or { TAIL ~ keyslots } , and the disc 51 provided with a single keyslot or slot engaging member
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH