Timed and Mechanical Action Fuzes, Clocks and Timers

Question 1

Difference between positive and organic safety?

Answer 1

Positive Safety - Blocking material forward of the firing pin to positively prevent final initiating action
Organic Safety - Safety block that comes with component, provided by manufacturer

Question 2

Define a tripwire?

Answer 2

An extension of a switch/fuze.

Question 3

What is the first thing to do when encountering a tripwire?

Answer 3

Trace both ends of wire ALL THE WAY to circuit.

Question 4

If an xray shows two wires seemingly going nowhere, what type of switch is it potentially?

Answer 4

Tin Foil switch

Question 5

What type of firing device is the military M5, “mousetrap” style switch?

Answer 5

Pressure Release

Question 6

What is the most hazardous switch to a bomb technician?

Answer 6

Anti-Disturbance

Question 7

Give three examples of an anti-disturbance switch?

Answer 7

Mercury switch, vibratory switch, tilt switch, vapor

Question 8

What causes a bi-metal switch to function?

Answer 8

Changes in temperature

Question 9

How does a barometric switch operate?

Answer 9

Changes in atmospheric pressure

Question 10

What improvised switches use a taut tripwire?

Answer 10

Clothespin or moustrap

Question 11

What two ways can a mousetrap fuze be used in a hazardous device?

Answer 11

1. Electrical circuit using striker as contact

2. Percussion type using striker as firing pin

Question 12

Using a clothespin type switch as a soluble material fuze, what is normally used to separate the contacts?

Answer 12

Aspirin

Question 13

What is the type by function of the M-1 Time pencil fuze?

Answer 13

Chemical delay

Question 14

What is normally employed in a circuit containing a trembler switch to provide an arming delay?

Answer 14

A clock or timer

Question 15

What could prevent a clock from not functioning a device?

Answer 15

paint or coating on the hands, lack of power, or forgetting to wind the clock

Question 16

What is the maximum delay using the minute hand on a clock? Hour hand?

Answer 16

59 minutes

11 hours 59 minutes

Question 17

Why is it important that the screw does not contact the face of a clock when using the clock hand method to fire a device?

Answer 17

If the screw comes in contact with face of clock, firing circuit would be completed (or short)

Question 18

When using the clock hand method, how is the time delay changed from minutes to hours?

Answer 18

By removing the minute hand

Question 19

Why do many clock devices misfire?

Answer 19

The bomber forgets to scrape insulation paint from contacts and hands

Question 20

What MUST be assumed if a clock is heard running in a device?

Answer 20

That the clock is either armed or fired by the clock