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HANDBOOK OF MECHANICAL DESIGN 



Fig. 87. — The round plunger is flat milled to a 

 90-deg. included angle and prevented from turning 

 by pin A engaging milled slots in the threaded plug. 

 In the end view shown at B, it can be seen that, if 

 the spring tension is to be adjusted, at least a half 

 turn must be given so that the flattened point will 

 coincide with the slot in the rod. 



Fig. 88.— When the 

 plunger diameter and the 

 wall thickness are suffi- 

 ciently large, a keyway 

 can be milled into the 

 plunger for engaging a 

 pin, which prevents it 

 from rotating. 



Fig. 89. — The plunger is milled 

 square with round corners and 

 the hole is partly broached; this 

 does awaj' with the necessity of 

 a key. The point is flat milled. 



Fig. 90. — Sometimes the plunger can 

 be milled with a flat which bears against 

 a pin, as shown in the end view to the 

 right ; thus the plunger is prevented from 

 turning in the hole. This design is par- 

 ticular!}' suitable for solid-type plungers. 



Fig. 91. — Here is shown a square-headed 

 plunger with its body turned round to 

 accommodate the spring in an eccentric hole, 

 thereby giving a support to the pin A, which 

 acts as a key. 



F I G. 92.— Probably 

 one of the simplest yet 

 most highly efficient 

 forms of detent is 

 merely a flat spring 

 bent to a 90-deg. in- 

 cluded angle and seat- 

 ing in V's milled in the 

 rod. 



Fig. 93. — With a long spring and a fairlj' 

 short phmger, a common flat-head wire nail 

 can be used to support the spring against buck- 

 ling. The spring also fits closely into the 

 plunger hole to gain support, and the plunger 

 is flanged at its upper end to prevent its slipping 

 through the hole. 



Fig. 94. — This design is similar to Fig. 88. When confined to a 

 small diameter, a smaller spring is placed within the larger. By 

 using a ,?i6 in. outside diameter outer spring, 25 per cent spring 

 tension can be gained by the addition of the inner spring. The 

 larger one has a sliding fit in the plunger and screw plug holes. 

 Two guide pins, the heads fittings closely into the larger spring, keep 

 the inner spring central and free from buckling. 



