GB1309547A - Tensioning apparatus for hollow bolts or hollow studs - Google Patents

Abstract

1309547 Tensioning hollow bolts and studs ENGLISH ELECTRIC CO Ltd 24 July 1970 [25 April 1969] 21195/69 Heading F2H Tensioning apparatus for a hollow bolt or stud comprises a member 3 attachable to the bolt or stud so as to close one end of the bore 2, a push-rod 7 for insertion into the bore to engage a reaction surface provided by or supported by the member, a fluid operated piston and cylinder 9, 14 removably attachable to the opposite end of the bolt or stud arranged such that the piston can engage the end of the push-rod which can thus be urged axially against the reaction surface by fluid pressure and so apply a compressive force to the pushrod and hence tension the bolt or stud. Push-rod 7 bears at one end against load spreader 27 in cap nut 3 and at the other end against piston 14 sliding in cylinder 9. Chamber 24 in cylinder 9 above the piston receives oil via inlet 22, and air is bled out via valve 23. Cup washer 18 held on piston 14 by nut 19 on stud 21 seals chamber 24 when pressure is applied to the oil in chamber 24 to apply stress to the bolt. Bush 10 enables cylinder 9 to be fitted to the desired size of bolt. Aperture 25 is for admitting a pin of a diameter which determines whether piston 14 has sufficient travel before contacting the top of bolt 1. In use, after the oil is pressurized, nut 4 is adjusted to take up the longitudinal strain. Instead of tensioning a bolt using a cap nut, the invention may tension a stud screwed directly into one of two or more members to be fastened.