Kinematics and kinetics of machinery; a text-book for colleges and technical schools |
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1921 Excerpt: ...engine is usually built in the form of two units each composed of four cylinders arranged as described in Art. 114. The axes of the cylinders in one group are inclined at some angle t to those of the other group. In each of these units the primary forces and couples are balanced, but the secondary forces are not. Since the two sets of unbalanced secondary forces are inclined to each other at an angle t, they cannot neutralize each other, and the engine is therefore not balanced as far as the secondary forces are concerned.1 117. The Twelve-cylinder Automobile-type Engine.--This engine is usually built up of two groups of six cylinders, each group being arranged as described in Art. 115. Since each of the groups is completely balanced in itself, the whole engine is in perfect balance with regard to both primary and secondary forces and couples. 118. The Radial Engine.--The radial or star engine is a multiple-cylinder engine having a single crank. The cylinders are all in the same radial plane, and all the connecting rods are attached by special devices to a common crank pin. The size of all the cylinders and the weights of all the reciprocating parts are equal. The general arrangement is shown in Fig. 193. 1 It can be readily shown that if the angle t is a right angle, the resultant shaking forces are in a plane at right angles to the plane bisecting the angle t. The value of the unbalanced force is the sum of the components of the two individual sets of secondary forces in a direction normal to the bisecting plane. If the engine has n cylinders, the angle between the lines of stroke of two adjacent cylinders is 2t/n = f. Then when the common crank makes an angle a with the line of stroke of cylinder n, it makes an angle a--f with the line of stroke of cylin...
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