Manual for submarine mining

by United States. War Department

The plug proper is held upright in a vise. The fuse can, the threads of the cap having been coated with ruberine, is screwed home and secured by its set-screw. The loading wire must be pulled through the opening in the plug proper with extreme care. It must not be injured in placing the fuse can in position and in screwing it home. The transformer leads are cut about 6 inches long, and the ends bared for 1 inch. The brass collar is screwed on the transformer; a little ruberine on the screw threads facilitates the operation. The connecting collar is slipped over the fuse leads and loading wire and allowed to rest on the fuse can. The transformer is supported by allowing two of the connecting bolts to slip into the holes in the collar; telegraph joints or brass jointers may be used between the secondary leads and the fuses and between the primary lead and the loading wire. The joints are wound with rubber tape, care being taken that there are no sharp ends to cut through the tape.

The transformer is raised vertically above the fuse can until the lead wires are extended. It is lowered and at the same time the leads are coiled in the base of the transformer. As the transformer and collar approach their position on the connecting bolts, the connecting collar is screwed on the transformer, the threads of the transformer having been covered with ruberine. The connecting collar will take care of the remainder of the leads and joints. The set-screw in the connecting collar is screwed home; the brass collar is placed on the connecting bolts and secured in position by the nuts and cotter pins.

The lips of the fuse can and connecting collar are covered with a thin covering of rubber cement. A piece of rubber tape is cut about 18 inches long and laid around this opening without stretching. A piece of protective tape is cut about 18 inches long and laid over the rubber tape with considerable stress. This forces the soft tape over the lips on the connecting collar and the fuse can and makes a tight but flexible joint. The stuffing box in the plug proper is prepared as under (a).

Great care must be taken not to injure the insulation of the loading wire in tightening up the follower in the stuffing box of the fuse can or of the plug proper.

(c) Trotol fuse can.—Starting with the compound plug dismantled.

Two mine service fuses, which have been tested for continuity of circuit, are cut with 12-inch leads, the wires bared for 1 inch and connected in multiple. A piece of loading wire is cut about 3 feet long and the ends bared for telegraph joints. The loading wire is threaded through the fuse can and cap. The threads of the fuse can are covered with ruberine. The can is screwed into the cap. The threads of the connecting collar are coated with ruberine and the collar is screwed down entirely. The loading wire should project about 4 inches above the connecting collar. The stuffing box of the cap is prepared. The plug proper is held upright in a vise. The fuse can cap, its threads having been coated with ruberine, is screwed firmly into the plug proper by means of a spanner wrench. The loading wire must be pulled through the opening in the plug proper with extreme care. It must not be injured in placing the fuse can in position and screwing it home.

The fuses are inserted in the fuse can, which is filled with trotol to the top of the connecting collar. The transformer leads are cut 4 inches long and the ends bared for 1 inch. The threads of the brass collar are covered with ruberine. It is screwed on the transformer. The latter is raised vertically above the fuse can and lowered on the connecting bolts.

Telegraph joints are made between the secondary leads and the fuses and the primary lead and the loading wire. The joints are wound with rubber tape, care being taken that no sharp ends cut through the tape. The leads and joints are coiled in the base of the transformer. The connecting collar, its threads having been covered with ruberine, is screwed upon the transformer against the brass collar. The bolt-securing nuts and cotter pins are placed in position. The stuffing box in the plug proper is assembled as under (a).

The actual resistance of the assembled plug in the vertical and the horizontal positions is determined by testing with a voltmeter.

In service, after the loaded plug tests out satisfactorily, all set screws are set up.