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