104 



HANDBOOK OF MECHANICAL DESIGN 



TAPER-PIN APPLICATIONS 



Fig. 109. Fig. 110. Fig. 111. Fig. 112. 



Fig. 109. — The conventional way of applying a taper pin, which depends upon friction to hold the pin in place. 

 In gear boxes and other sealed mechanisms where it would be injurious for a pin to work loose, positive locking means 

 must be provided. 



Fig. 110. — The large end of the pin comes just below the surface of the external member it is holding and is 

 staked as shown in the plan view. These little swellings, or burrs, straighten out or shear off it it is necessary to remove 

 the pin, but usually will score the surface of the pin. It should be noted that cast iron does not stake readily as it 

 is brittle and will not flow. 



Fig. 111. — A small cotter pin retains but does not prevent loosening of the taper pin. 



Fig. 112. — With this design, the taper pin is pulled tight with the hex nut which bears against a flat on the 

 external member, although this flat is not necessary. Some engineers prefer to use a lock washer under the nut, in 

 which case both the nut and the external member should not be Hardened. Thus the lock washer can get a grip. 



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Fig. 113. Fig. 114. 



Fig. 113. — In this design, the screw stud is expanded and locked by the use of a taper pin. The stud is slitted 

 as shown in the end view. The taper pin rests in the bottom of the hole, and the stud is screwed in until it can be 

 turned no farther. 



Fig. 114. — This shows a twofold purpose. The sa wed-off taper pin acts as a holding device and as a key guide to 

 the sUdable inner member. 



Fig. 115. Fig. 116. Fig. 117. Fig. 118. 



Fig. 115. — Here the pin is flattened off and used as a wedge. This method calls for accurate work, but, if the 

 hole is reamed too large or wears too much, the next larger taper pin maj' be used. 



Figs. 116, 117, and 118. — When a taper pin is to be used in a blind hole, one of the three methods shown here can 

 be used. To facilitate loosening the pin, a square may be milled at the large end as in Fig. 116. It is well to cj'anide 

 this squared end. Figure 117 shows a special form with a square head, the flat of which is equal to the large diameter. 

 This type should be hardened all over and ground on the body. In Fig. 118, the pin is threaded and jacked out by a 

 hex nut against a washer. The top end should be cyanided so it will not be pounded over during assembly. A fine 

 thread should be used so as not to weaken the pin by too small a root diameter. For appearances, the washer and 

 nut are left on, but this does not render it foolproof. This form is used as a dowel pin where the held member must 

 be located accurately. 



