Patent GB-874409-A (GB)
Title: Improvements in or relating to cable sheathing
Inventor: LEE EDWIN CHARLES
IPC: H01B13/22
Filed: 1959-09-30
Abstract: 874,409. Making sheathed cables; drawing. STANDARD TELEPHONES & CABLES Ltd. Sept. 30, 1959, No. 33136/59. Classes 83 (2) and 83 (4). In a method of sheathing a cable 38 by drawing it into an oversize metal tube 4 and then sinking the tube on to the cable, the tube is supported in a metal pipe 1 while the cable is drawn into it and the assembly is drawn from the pipe through a sinking die 45. The method comprises the following steps: A pipe 1 is erected between stations A and B with an electrically insulated tow-line 5 therein, which extends beyond each end of the pipe and which is used to draw a tube 4, which has been straightened and cleaned, into the pipe. The tow line is attached to the tube by a gripper 8 and passes round a capstan 13 and on to a take-up reel 14. At the mouth of the pipe is an electrically-operated measuring device 17 which requires the presence of a metal tube to complete its circuit, and which is connected to two counters. One of these counters is preset to indicate the length of tube to be drawn into the pipe and counts down to zero, the other counts up from zero as the tube passes. When the first counter reaches zero the hauling automatically stops, the tube 4 is cut off and the surplus wound back on to a drum 6. A plug 26 to which is attached a light tow-line 23 is placed in the trailing end of the tube 4 which is swaged down a little behind the plug. The tube 4 is then pulled further through the pipe until the end can be engaged by a gripper 30, and a vacuum pump is attached to draw the plug 26 through the tube 4 to station A. The light line 23 is used to pull the tow-line 5 back to station B where it is passed round the capstan 24 and fastened to the take-up reel 32. The other end of tow-line 5 is fastened to the cable 38 by a swivel 34, a ball 37 and a grip 40 and the cable is pulled into the tube 4 through a measuring device 41 similar to the device 17. When the appropriate length of cable has been pulled into the tube, and the leading end of the cable is coincident with the end of the tube, the gripper 30 automatically opens and the cable 38 and tube 4 advance together to the end of the pipe where they stop automatically. The towline 5 is removed and the end of the tube reduced in a swaging device 22 to enter the sinking die 45, a grip 46 attached and a main hauling line 47 is wound round the capstan 24 and attached to the grip. At station A the plug 26 and gripper 8 are placed in a carrier 43 which is attached to the end of the cable 38 and a further tow-line 44 is connected to the carrier. The sinking operation commences and is stopped automatically when the end of the tube passes a pair of contacts 42 in the pipe. The tube is then advanced under manual control until the carrier 43 emerges from the pipe so that it can be detached and the sinking operation then completed. The plug 26 and grip 8 are removed from the carrier which is then drawn back, together with the swivel 34, the ball 37 and the cable towing grip 40 to station A, by the further tow-line 44 which also draws the tow-line 5 back through the pipe.