Description: The essential parts of this fuze are the generator, firing circuit, and the air pressure operated switch. The generator consists of a series of coils secured to a closing plate and four quarter section magnets encased within a brass sleeve which rides on a ball race seated on the coils. The vanes do not come off but are threaded on securely, and in rotation turn the magnets around the coils. The firing circuit consists of two plug leads which conduct the current from the generator to an air pressure operated switch. Leads to a squib plug into the circuit from the switch. The switch consists of two con-tact points. One point is attached to a pivoted lever and a leaf spring bears against this lever and tends to force the contact point against the other point on the setting screw. A stud attached to an aneroid type metallic vaccum box bears against the other side of the lever, however, and tends to hold the contact points apart. By rotating the setting screw the distance between the contact point can be adjusted. Twelve small air ports permit air to enter and pass down the hollow spindle into the fuze.

Operation: On release from the plane, the arming wire is withdrawn from the holes in the arming vanes and the vanes are freed to rotate. An electric current is generated by the rotation of the magnets around the coils. Air entering the small holes in the spindle exerts pressure on the vaccum box causing it to contract and lift the stud from the switch lever. The leaf spring forces the lever up and thus closes the contact points. The circuit being complete, the squib fires.

The functioning altitude can be set by inserting the fuze in a testing apparatus and ad-justing the setting screw in both direction until the contact points are just closed and a pilot light lights. The zero mark on the altitude scale is then placed at this point and the functioning altitude is set by rotating the pointers on the setting screw to the desired height.

Remarks: The only apparent difference between the D-1 (a) and D-1 (b) is length; the D-1 (a) body being 3 7/8 inches long and the D-1 (b) 4 3/8 inches. In addition, this same fuze has been found with a bakelite body instead of aluminum, but is otherwise the same.

Figure 110 – D-1 (a) and D-1 (b) Bomb Fuzes