Page:The Kinematics of Machinery.djvu/596

 574

�KINEMATICS OF MACHINERY.

�chain. Both are placed upon the link 6 '7, and give a very near approximation to the required motion. Compound (C") chains are also employed in numerous modifications as weighing machines.

The skew screw-chain (<7$^P^), which we examined in 154, has also come lately into use in the " dogs " used upon the face plates of lathes,* &c., in several forms.

Another example which is in place here is that of the reverted wheel-chain ((7 z2 OJj'), which we examined in 105. 1 must content myself here with merely mentioning this : we have already

seen what an immense number of me- chanisms are formed from the chain

j n"\, 2 <-v-

As a fifth and last example we shall take the chain shown in a general form in Fig. 431, which gives us some very notable mechanisms. It is a combined chain consisting of the simple spur- wheel chain (O t C') with two links, each p ra 430 containing two parallel cylinder pairs,

added to the two wheels. The chain lias therefore five links and six pairs, the latter being the cylinder pairs

���Fri. 431.

1, 2, 3, 4, 5 and the pair 6 of the form (C 2 ). We may write it shortly as (0JQ) and in full :

6 d 1 a 2 I 3 c 6

ii

..

�d 5 e 4 c

p. 215.
 * See for example Danbtiry's drill-chuck, Scientific American, vol. xix. (1373)

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