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| Japanese Explosive Ordnance – Bombs, Bomb Fuzes, Land Mines,
Grenades, Firing Devices and Sabotage Devices |
| Chapter 3 - Section 2 |
| Firing Devices and Sabotage Devices |
| Twenty-Four-Hour Demolition Clock |
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This clock will fire a charge electrically after a delay of up to 24 hours. It has two bridg-ing contact arms which ride on two semicircular electrical contacts connected by leads through a battery to the charge. The releation of the two arms to each other governs the amount of delay. They may be set only in one hour increments. |
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No outer protective case for the working parts of the clock is provided. |
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Type 99 Long-Delay Demolition Clock |
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This clock is electrically wound and fires its charge electrically. It has a maximum delay time of 10 1/2 days, and winds itself every 4 3/4 minutes. Setting is accomplished by ro-tating the graduated dial to the desired delay time. At completion of the delay time, a spring-loaded contact arm drops into an aperture on the outer rim of the dial, and closes the firing circuit. |
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Additional gear trains and setting dials may be provided in some cases to extend delay time to 30 or 60 days. |
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Power for the operation of the clock and firing of the charge is provided by a battery contained in the clock's wooden protective case. |
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Figure 191 – Demolition Clocks. |
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| Seven-and-One-Half-Day Demolition Clock |
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Apparently of European design, this clock is smaller and more finely made than any of the others. It is hand wound by means of an attached key, and is set by means of a ratchet bearing against the outer edge of the dial. The dial is graduated in one hour intervals to 7 1/2 days. The clock fires when a trigger arm falls into an aperture on the circumferen-ce of the dial, releasing the spring-loaded striker. The striker aperture is threaded on the inside to take a blasting cap, and on the outside to take a demolition block. |
| Type 92 - Seven-Day Demolition Clock |
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This is a spring-driven clock with settings up to 7 days. It is capable of firing a charge either electrically or mechanically. Electric leads connect the contacts on the clock through a battery to the charge. At the base of the clock is a receptacle for safety fuze which is used if the clock is to fire its charge mechanically. A graduated ring is provided at the base of the clock for the purpose of setting delay time. |
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Figure 192 – Demolition Clock. |
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