112 



HANDBOOK OF MECHANICAL DESIGN 



/ Flo'f reioining plaie 



/! ■ — — — I I 



^^^> S^-.iT" 



Recianqulor lock 



boli milled ouf 

 cenlrally looccom- 

 modafe acluaflng 

 spring 



Fig. 194. — In this design the rectangular lock bolt is 

 milled out centrally to accommodate actuating spring. 

 A pin is provided tor hand actuation when desired. 



^'Lock boll wilh 

 rack machined 



~ 'Pinion manually 

 aclua led by 

 wrench or 

 handle 



• Fig. 195. — A rack is machined in the lock bolt. 

 Pinion meshing with rack is manxiaUy actuated with 

 wrench or handle. 



Fig. 196. — When indexing starts, the lock 

 bolt is released and rides on the periphery 

 of the plate. At point A, it starts to sUde 

 down the inclined slot. At B is shown the 

 shearing or wearing action that takes place. 

 In case the plate has overrun or indexed past its 

 position as at C, the spring behind the lock bolt 

 is required to turn the plate, together with 

 the whole rotating mass attached to it, back- 

 ward, resulting in wear on the side opposite 

 to that shown at B. At Z>, complete engage- 

 ment is shown. Rounded corners as at X 

 and Y should be provided. There should be 

 plenty of clearance as at E to allow for wear 

 because of the small angle of the slot. At H is 

 shown an improved form of gear. It assures 

 clearance and provides for grinding of the, 

 angular surfaces if necessary. If the lock-bolt 

 spring is not strong enough to seat the bolt by 

 rotating the plate, vibration will usually com- 

 plete the seating, causing chatter at the cutting 

 tool or spindle and wear on the bolt and slot. 

 In this type of bolt, the angular sides are alike, 

 hence the direction may be opposite from that 

 shown. 



Fig. 197. — More accurate form of 

 lock bolt, which is claimed by many 

 to be the correct method for this 

 type of design. The inclined sur- 

 face gets the wear as it seats the 

 the bolt, whereas the straight or 

 radial side positions the bolt accu- 

 rately. Positions A, B, C, and D 

 correspond to those in Fig. 196, and 

 indicate that the corners X and Y 

 should be rounded. At H is shown 

 how the groove is ground. Other 

 notations are the same as given in 

 Fig. 196. 



Milled \ 



— Pin pre venis 

 ro la I ion 



Fig. 198. 



'Tapered gibs perrnii accurole 

 ,-D^iJ. n selfinq of boll in bolh side 



Fig. 199. 



