An ebonite beam B is rocked up and down rapidly by a train of mechanism, and moves the cranks FIG.
In this engine the two piston-rods of one side are not coupled to a common cross-head, but drive on separate cranks at an angle of 180°, the pair of 180° cranks on each side being placed at right angles.
All cylinders drive on one crank-axle with three cranks at 120°.
The low-pressure cylinders drive on the leading crank-axle with cranks at right angles, the highpressure cylinders driving on the trailing wheels.
When the four cranks are placed with two pairs at 180°, the pairs being at 90°, the forces are balanced without the introduction of a hammer-blow, but there remain large unbalanced couples, which if balanced by means of revolving weights in the wheels again reintroduce the hammerblow, and if left unbalanced tend to make the engine oscillate in a horizontal plane at high speed.
As the cranks are set go apart, there is no dead centre, and the engine is able to start under full load from any point of the stroke.
At first the rolls were driven by workmen by means of cranks, but later they were worked by horses, mules or water-power.
Circular shifting is regulated by attaching two or more points of the shifting piece to ends of equal and parallel rotating cranks, or by combinations of wheel-work to be afterwards described.
As an example of circular shifting may be cited the motion of the coupling rod, by which the parallel and equal cranks upon two or more axles of a locomotive engine are connected and made to rotate simultaneously.
Linkwoyk in GeneralThe pieces which are connected by linkwork, if they rotate or oscillate, are usually called cranks, beams and levers.
Coupling of Parallel Axes.Two or more parallel shafts (such as those of a locomotive engine, with two or more pairs of driving wheels) are made to rotate with constantly equal angular velocities by having equal cranks, which are maintained parallel by a coupling-rod of such a length that the line of c000exion is equal to the distance between the axes.
The cranks pass their deadpoints simultaneously.
To obviate the unsteadiness of motion which this tends to cause, the shafts are provided with a second set of cranks at right angles to the first, connected by means of a similar coupling-rod, so that one set of cranks pass their dead points at the instant when the other set are farthest from theirs.
For Moscow society Pierre was the nicest, kindest, most intellectual, merriest, and most magnanimous of cranks, a heedless, genial nobleman of the old Russian type.