GB1118049A - Hydropneumatic cable tensioner - Google Patents

Abstract

1,118,049. Dashpots. RUCKER CO. 7 Feb., No. 5882/67. Heading F2S. [Also in Division B8] A hydropneumatic cable tensioner comprises a piston 16 having a piston rod 17 carrying a sheave block and slidable in a cylinder 12 carrying a sheave block, the cable being reeved around the sheaves of the two blocks such that as the piston moves outwardly from the cylinder, the cable is tensioned. Pressurized air is supplied to the cylinder at the end 31 and maintains the cable under tension. Oil is supplied from a reservoir 38 to the cylinder at the end from which the piston rod extends. The oil in the reservoir is maintained under pressure by feeding pressurized air from the cylinder at 51 to the reservoir via a pressure-reducing valve 53. Oil enters the cylinder 12 through two ports 73, 48, one of which is closed by the piston passing over it during extension and one of which is always open, the latter port 48 being fed via a non-return valve 62 around which a variable-flow valve 64 is shunted. During normal operation, the cable is tensioned by the air in the cylinder. With a sudden release of load in the cable e.g. cable breakage, the piston tends to extend rapidly and the oil damps down this motion. A conical-shaped surface 72 of the piston passing the first said oil port 73 gradually restricts the outflow of oil therethrough and the variable flow valve 64 restricts the oil flow out of the second said port 48. A sensing mechanism coupled to the piston and cylinder indicates their relative positions. In the embodiment of Fig. 6 (not shown) the oil reservoir is coaxially mounted around the cylinder.