Page:Motors and motor-driving (1902).djvu/158

126 weight to fly outwards, describing a circle, and if the hand is revolved rapidly, the weight will fly still further out until the string forms a right angle with the perpendicular. Now in fig. 17 occupies the position of the hand. It is a gear wheel attached to shaft (the two-to-one shaft) and is operated by a smaller gear wheel on the engine shaft,  are two weights pivoted at one of the extremities of the gear wheel, and which of course are free to fly outwards when the gear is rapidly revolving.

Now we would ask our readers for a moment to look at the diagram irrespective of the dotted lines, as this represents the position of affairs when the gear wheel is at rest. It will be observed that there are two arms which carry the weights and are pivoted at. is a sleeve which is free to slide upon the shaft, and on this sleeve are two cams,  and a collar , the latter being a true circle, and the other two eccentrics. represents the end of the hammer as shown in figs. 14, 15, and 16. Now, so long as rests upon the circular collar, the exhaust valves open in regular sequence (see fig. 14), and neither cylinder is cut out.

We shall proceed to describe how the hammer is influenced to slip on to the eccentric cams  and, and so make one or both cylinders cut out.

We would now call special attention to the dotted lines in the diagram. The weights are connected by springs regulated to the proper tension, but which, for clearness sake, are not shown in the diagram. When the speed of spur wheel reaches the maximum pace at which the engine has been set, the weights  fly out until they assume the position  as shown in the diagram. The ends of the arms are thus moved forward until they assume the positions shown in  and in moving push against, and consequently move the entire sleeve  forward until  assumes the position , and the collar and cams  and , positions  and. The hammer, not being free to move laterally, climbs in succession from collar to cam , and from cam  to