Patent GB-1140636-A (GB)
Title: Improvements in or relating to duct clamps
Inventor: BROWNHILL FRANK DENISON
IPC: F16L23/10
Filed: 1967-11-14
Abstract: 1,140,636. Clamps. ROLLS-ROYCE Ltd. 14 Nov., 1967, No. 51764/67. Heading E2B. A clamp of the type adapted to be used for a clamping together in endwise coaxial abutment a pair of ducts, each duct having a radially outwardly extending flange member at its end abutting the other duct, the flange members abutting in coaxial relationship and being tapered such that the axial width of the abutting flanges is less at their radially outer portions than at their radially inner portions comprises a part circular clamp ring 21 having a groove which is adapted to receive the said flange members, and a strap device engageable with the ends of the clamp ring and adapted to draw the ends of the clamp ring towards each other thereby imparting forces to the flange members to maintain them in coaxial abutment, the strap device having a radially inwardly projecting peg 68 adapted to engage a locating slot 20 in one of the said flange members in such a way that when the peg is engaged in the slot the clamp is angularly located with 'respect to the axis of the slotted flange member. In the construction shown the strap device comprises a sheet metal frame 'member 60 and a tie bolt assembly; the frame member 60 comprises a side member 61, 62 and an interconnecting cross member 63 from which the .peg 68 projects. The tie bolt assembly consists of a pin 38 disposed in a hole 28 in one of the lugs 26 of the clamp ring the pin 38 passing through a ring 45 of a tie bolt 44 so that the tie bolt is pivotally attached to the lug 26. The ring 45 is disposed in a slot 31 in the lug 26. The tie bolt extends through a slot 35 of the lug 27 and the end portion 46 of the tie bolt remote from the ring 45 is of smaller diameter and is screw threaded; a chamfered shoulder 47 is thus provided between the portion 46 and the shank of the tie bolt. A thrust collar 50 is mounted on the tie bolt 44 the thrust collar comprising a first substantially cylindrical portion 51 and a second substantially cylindrical portion 52 whose axis is perpendicular to the axis of the first portion. The tie bolt passes through a bore 55 in the portion 52, the bore having a chamfered step 57. A nut 58 is screwed onto the threaded end portion 46 of the bolt 44 and bears against the end face of portion 52 of the thrust collar 50 which itself engages an arcuate cut-out 29 in the lug 27. Rotation of the nut thus forces the lugs 26 and 27 together The side members 61, 62 of the frame member 60 have elongated slots 65, 66 respective end portions of the thrust collar and the pin 38 entering the slots the side members being retained on the end portions by nuts 40, 54. The length of the slots is such as to allow the full range of movement of the thrust collar 50 along the bolt 44 and the relative positions of the shoulders 47 and 57 of the tie bolt and collar are arranged so that as the nut 58 is tightened the shoulders come into abutment and prevent further tightening of the nut before the clamp ring 21 has been sufficiently reduced in diameter for the outer edges of the flanges 12,. 13 of the ducts to engage the bottom of the groove 22. Both of the flange members can have a locating slot 20 if desired.