Guide track means

Claim 1

ENDLESS BALL TRACK BEARING UNIT, COMPRISING A BODY, AT LEAST ONE STRAIGHT LINEAR BALL GUIDE TRACK GROOVE IN THE BODY PERIPHERY, AT LEAST ONE BALL GUIDE PASSAGEWAY LONGITUDINALLY THROUGH THE BODY AND PARALLEL WITH SAID TRACK, SAID TRACK AND PASSAGEWAY EXTENDING FROM END TO END OF SAID BODY, A SUBSTANTIALLY NARROW PROJECTING PART ON EACH OF THE BODY END FACES IN ALIGNMENT WITH THE TRACK GROOVE AND PASSAGEWAY, SAID PART HAVING A CURVED TRACK PROFILE, A REMOVABLE CAP ON EACH END OF THE BODY, EACH CAP HAVING A CURVED CAVITY TO RECEIVE A SAID PROJECTING PART AND CO-OPERATE WITH SAID PROFILE TRACK TO FORM AN END GUIDE PATH FOR LINKING THE ADJACENT END OF THE TRACK GROOVE WITH THE ADJACENT OPEN END OF THE GUIDE PASSAGEWAY, A SET OF BALL BEARINGS FILLING THE TRACK GROOVE, END PATHS AND PASSAGEWAY, SAID BODY HAVING AT LEAST PART OF ITS PERIPHERY CURVED TO ENGAGE A STRUCTURE MEMBER, AND SECURING BOLTS FOR PASSING THROUGH THE BODY WITH CLEARANCE INTO SAID MEMBER, THE ARRANGEMENT BEING SUCH AS TO ENABLE THE BODY TO BE SELF-ALIGNING ABOUT A LINEAL LINE INTO AN OPERATIVE POSITION ON SAID STRUCTURE MEMBER FOR THE BALLS IN THE TRACK GROOVE TO BE LOCATED IN A TRACK PROVIDED IN ANOTHER STRUCTURE GUIDE MEMBER.