Description
The fuze head screws into an adapter fixed in the base of the rocket body, and the gasket and luting on the threads make a gas-tight seal. The top of the fuze is exposed to the front end of the rocket motor. The Base Fuze Mk 146 Mod 1 differs in that it has a more sensitive firing train. The fuze is shipped assembled in the base of the rocket head, and is not to be removed.
A few of the early experimental models incorporated a delay of 0.02 second to allow penetration. The Base Fuze Mk 157 was developed from these. The later models of this fuze have undergone the following modifications :
1. The inlet shield has been modified. The two outside legs are slightly longer than the flat base of the shield, so that the inlet screen will not be crushed when the inlet screw is tightened.
2. The ball retaining plug, slaked in place, has replaced the screw plug.
3. A safety pin has been fitted below the spacer sleeve to facilitate assembly operations.
4. The detonator shutter has taken on ail oval shape, eliminating1 the former squared comers.
5. The latest lots of Base Fuzes Mk 146 have been further altered to increase the overall sensitivity of the fuze by using a weaker creep spring, a more sensitive primer, and a more tapered firing point.
Functioning
When the rocket is fired, gas under considerable pressure from the rocket motor passes through the inlet screen underneath the inlet screw and enters the pressure chamber. As the gas pressure builds up. the diaphragm bears against the aiming plunger, breaking the shear wire and forcing the arming plunger inward. The locking ball, which is preventing the rearward .movement of the striker block, is forced over by the pressure of the springloaded striker block into the narrow portion of the arming plunger. The striker spring forces the striker block rearward, retracting the firing pin from the detonator shutter. The shutter is still prevented from moving across the fuze by action of its spring until after deceleration begins. since the force of set-back thrusts the shutter back and causes the shutter locking pin to engage in a recess in the firing-pin guide. After burning of the propellant ceases and deceleration begins, the shutter rides forward, disengaging the locking pin from the guide. The shutter spring forces the shutter across the shutter cavity, where it is locked in the armed position by a detent which is housed in the firing-pin guide and which engages a recess in the shutter. On impact, inertia drives the striker block forward against its spring, the firing pin striking the detonator.
Hazardous Components
No information about hazardous components.
See Also
Source(s)
OP 1664, Volume 1 - US Explosive Ordnance (1947)
