Description
These devices are clockwork mechanisms designed to tire demolition charges with a time delay, adjustable — depending upon the model — from five seconds to eleven hours. They are designed for firing either activator well, or detonating cord charges.
The principal parts of this series are the body, head, timing disc, timing-disc lever, cam, firing pin. arming pin, and cotter pin.
The Mk 12 may be set from 5 to 90 seconds delay; Mk 13, from 1 minute to 1 hour delay; Mk 15, from 1/4 to 11 hours delay. Because the Mk 15 is as much as 30% inaccurate for settings beneath one hour, these calibrations are coated with red paint as a warning.
Tabs have been placed under the screws fastening the head to the body, to make possible identification by feel in the dark, as follows: Mk 12 — no tab; Mk 13 — one tab: Mk 15 — two tabs.
This device can also be used in booby traps as a tripwire firing device.
Functioning
When the cotter pin is removed, the spring-loaded arming pin moves out of the notch in the timing disc. The timing disc, driven by a pre-wound clock movement, can then revolve until the notch meets the timing-disc lever. The lever position and, therefore, the elapsed time, is changed by rotating the head to the desired time setting. A spring-loaded firing pin, positively locked in place by a series of cams and levers, is released when the timing disc lever enters the notch. The firing pin penetrates the waterproof diaphragm and fires the percussion cap. The flash of flame which results will detonate the Special Non Electric Cap or the Detonating Cord Initiator Mk 2 Mod 0.
Hazardous Components
No information about hazardous components.
See Also
Nothing else to see.
Source(s)
OP 1664, Volume 2 - US Explosive Ordnance (1947)
