GB1397748A - Method and apparatus for length stabilization of a cable - Google Patents

Abstract

1397748 Stretching USS ENGS & CONSULTANTS Inc 26 July 1972 [4 Aug 1971] 35012/72 Headings B3E and B3V The length of a cable is stabilized by subjecting the cable while moving to tensioning cycles each consisting of the applications of a prestressing load followed by a relaxing load. As shown, an armoured electrical oil well lagging cable 2 is fed from a reel 4 to a driven take-up reel 28. Between the reels 4, 28 are braking sheaves 8, fixed sheaves 10-22, a movable sheave 24 and power-driven capstan sheaves 26. The braking sheaves 8, through gearing 70 and a gear-box 72, drive a pump 74 which is connected to an adjustable relief valve 80 for setting the braking effect. The valve 80 is by-passed cyclically by operation of a valve 84 by a motor-driven cam 86, so as to vary the prestressing load and return the pumped fluid to a tank 76. An hydraulic jack 56, 58 for the sheave 24 is supplied through a pump 62, an adjustable relief valve 64 and a valve 66, the supply being controlled by an electricallyoperated valve 50 which is connected to a potentiometer (48), Fig. 3 (not shown), operated by movement of the sheave 24. In operation, when the valve 80 is being bypassed for minium braking effect, the released tension tends to move the piston 56 to the left, thus actuating the potentiometer (48) for resetting valve 50 and moving the piston to the right to a neutral position for minimum tension. Conversely, when valve 80 is not being bypassed, the increased tension moves the piston 56 further to the right only to be returned to the left to a neutral position for maximum tension. An electrical heating system 90 may be operative during tensioning.