Файл:TFrictionTubeMkIV.jpg

British "T" Friction Tube Mk IV, for BL guns, 1914.

Height approx. 1 7/8 inches. T approx 1 7/8 inches. Tube tapering to 1/4 inch.
A hole is bored through the side of the head, at right angles to the wire passing through. The hole is filled with detonating composition, surrounding the roughened part of the wire, and the hole is sealed up.
Action :-

• The gunlayer inserts the tube in the breech vent.
• A lanyard is attached to the loop in the wire in the T.
• The gunlayer pulls, or extends and "chops down on" the lanyard.
• The friction wire is pulled through the detonating composition and out of the head, igniting the detonating composition by friction.
• The flash passes down the small hole in the top of the body, over the copper ball, through the fire-holes in the brass screw-plug, and ignites the powder.
• The expanding gas forces the copper ball up into the cone seating, sealing the vent on the inside of the tube, and expands the tube body, sealing the vent outside the tube.

Used with :-

• BL 12 pounder 6 cwt Gun
• BL 15 pounder Gun
• BL 2.75 inch Mountain Gun
• BL 5 inch Howitzer
• BL 5.4 inch Howitzer
• BL 6 inch 30 cwt Howitzer