The chair , {TAIL ~ device carriage} , and {HEAD ~ footrest assembly} are coupled to the shaft to selectively pivot together about the shaft , and in such a manner that a constant spatial relationship is maintained between the chair and the device carriage  
The chair , { TAIL ~ device carriage } , and { HEAD ~ footrest assembly } are coupled to the shaft to selectively pivot together about the shaft , and in such a manner that a constant spatial relationship is maintained between the chair and the device carriage
OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH