tensoning device

Abstract

The present invention relates broadly to a tensioning device ( 1 ) for a strata support cable tendon ( 80 ). The tensioning device ( 1 ) comprises a barrel fitting ( 60 ) and a barrel actuator ( 50 ). The tensioning device ( 1 ) also includes locking means ( 40 ) coupled to the barrel actuator ( 50 ) for releasable engagement with the barrel fitting ( 60 ) to temporarily prevent movement of the actuator ( 50 ) relative to the barrel fitting ( 60 ). Release of the locking means ( 40 ) from the barrel fitting ( 60 ) permits longitudinal movement of the barrel actuator ( 50 ) relative to the barrel fitting ( 60 ) for tensioning of the cable or tendon ( 80 ) within the cavity.

1 . A tensioning device for a strata support cable or tendon, said device comprising:
 a barrel fitting being elongate and adapted to attach to the cable or tendon;   a barrel actuator being movably connected to the barrel fitting for longitudinal movement relative to the barrel fitting; and   locking means operatively coupled to the barrel actuator for releasable engagement with the barrel fitting, or vice versa, to temporarily prevent at least longitudinal movement of said actuator relative to the barrel fitting whereby movement of the barrel actuator effects a corresponding movement of the barrel fitting and the cable or tendon for its placement in a cavity and thereafter release of the locking means from the barrel fitting, or the barrel actuator, permits longitudinal movement of the barrel actuator relative to the barrel fitting for tensioning of the cable or tendon within the cavity.   
   
   
       2 . A tensioning device as defined in  claim 1  wherein the barrel fitting is externally threaded and the barrel actuator includes a nut threadably attached to the barrel fitting. 
   
   
       3 . A tensioning device as defined in  claim 1  wherein the barrel fitting is of a 2-piece construction including a barrel head connected to a threaded barrel section. 
   
   
       4 . A tensioning device as defined in  claim 1  wherein the locking means is in the form of a mechanical arrangement or chemical means. 
   
   
       5 . A tensioning device as defined in  claim 4  wherein the mechanical locking arrangement includes a pin or rod slidably located in a corresponding hole in the barrel actuator and being configured for engagement with a mating recess in the barrel fitting. 
   
   
       6 . A tensioning device as defined in  claim 5  wherein the pin or rod is in the form of a shear pin designed to break or fracture at a predetermined load to then permit movement of the barrel actuator relative to the barrel fitting. 
   
   
       7 . A tensioning device as defined in  claim 2  wherein the mechanical locking arrangement includes a variation in the configuration of the external thread of the barrel fitting. 
   
   
       8 . A tensioning device as defined in  claim 1  wherein the tensioning device comprises a strata plate having a central aperture through which the cable or tendon passes. 
   
   
       9 . A tensioning device as defined in  claim 8  wherein the tensioning device comprises a bearing assembly coupled to the barrel fitting to prevent relative rotational movement, the bearing assembly being arranged to locate intermediate the barrel actuator and the strata plate for abutment with the barrel actuator on tensioning of the cable or tendon. 
   
   
       10 . A tensioning device as defined in  claim 9  wherein the bearing assembly includes a domed washer being configured to abut the strata plate and permit angular installation of the cable or tendon relative to said plate. 
   
   
       11 . A tensioning device as defined in  claim 8  wherein the bearing assembly includes a friction washer, friction bearing, or thrust bearing located between the movable actuator and the domed washer. 
   
   
       12 . A tensioning device as defined in  claim 10  wherein the domed washer includes a roughened or soft exterior surface being designed to engage a corresponding surface in the strata plate to prevent rotational movement whilst permitting tilting of the domed washer relative to the strata plate to accommodate angular installation of the cable or tendon. 
   
   
       13 . A tensioning device as defined in  claim 1  wherein the barrel fitting includes an axially oriented groove along its external surface, the groove being configured to engage a key in the domed washer to prevent rotational movement whilst allowing relative longitudinal movement. 
   
   
       14 . A tensioning device as defined in  claim 13  wherein the groove is one of a pair of grooves located on opposing sides of the barrel fitting. 
   
   
       15 . A tensioning device as defined in  claim 1  also comprising a wedge assembly having an aperture for receipt of the cable or tendon, the wedge assembly having a tapered outside surface configured for engagement with a corresponding inside surface of the barrel fitting for clamping about the cable or tendon. 
   
   
       16 . A tensioning device as defined in  claim 15  wherein the wedge assembly is shaped in the form of a conical frustum and is of a split design. 
   
   
       17 . A tensioning device as defined in  claim 1  wherein the cavity in which the cable or tendon is placed is a pre-drilled cavity. 
   
   
       18 . A tensioning device as defined in  claim 1  wherein the strata support cable or tendon includes wire rope. 
   
   
       19 . A tensioning device for a strata support cable or tendon, said device comprising:
 a barrel fitting being elongate and adapted to attach to the cable or tendon;   a barrel actuator being movably connected to the barrel fitting for longitudinal movement relative to the barrel fitting; and   a locking portion arranged to temporarily prevent at least longitudinal movement of said actuator relative to the barrel fitting whereby movement of the barrel actuator effects a corresponding movement of the barrel fitting and the cable or tendon for its placement in a cavity, and thereafter release of the locking portion permits longitudinal movement of the barrel actuator relative to the barrel fitting for tensioning of the cable or tendon within the cavity.   
   
   
       20 . A tensioning device as defined in  claim 19  wherein the barrel fitting is externally threaded and the barrel actuator includes a nut threadably attached to the barrel fitting. 
   
   
       21 . A tensioning device as defined in  claim 19  wherein the locking portion is constructed to release upon application of a predetermined load to then permit movement of the barrel actuator relative to the barrel fitting. 
   
   
       22 . A tensioning device as defined in  claim 19  wherein the tensioning device comprises a strata plate having a central aperture through which the cable or tendon passes, and a bearing assembly coupled to the barrel fitting to prevent relative rotational movement, the bearing assembly being arranged to locate intermediate the barrel actuator and the strata plate for abutment with the barrel actuator on tensioning of the cable or tendon. 
   
   
       23 . A tensioning device as defined in  claim 19  also comprising a wedge assembly having an aperture for receipt of the cable or tendon, the wedge assembly having a tapered outside surface configured for engagement with a corresponding inside surface of the barrel fitting for clamping about the cable or tendon.