Operation of the Progressive Gear.—The relative arrangement of the parts gives a comprehensive idea of the mechanical ideas involved, and by referring to the description and illustrations of the gears, it will be seen how the change lever 7, in moving back one notch, from its neutral position, will throw the gear G into mesh with L, and another movement of the lever to the next notch, will cause the crown teeth on G, to engage with the teeth on gear E, and thus effect a high gear connection.
The Selector Mechanism.—This is more or less confusing to the novice, and the accompanying illustration, Fig. 52, shows a perspective view, in which some of the parts are drawn out of proportion, merely for the sake of clearness. The aim is to show principles and not details of exact mechanical construction.
Fig. 52. Selective Control Mechanism.
Selector Bars.—The two selector bars A B, are mounted in guide ways so they move longitudinally alongside each other a limited distance. Each bar has an arm, as at C D, the end of each having a curved finger E to engage the annular grooves on the hubs of the shifting gears.
Above these bars, and at right angles thereto, is a rock-shaft F, mounted in bearings G G, so that it is longitudinally-movable a limited distance, to shift the selector lever H from one bar A to the other bar B.
Shifting Lever.—The selector I has two fore and aft slots J K, these slots being of such width that the gear shifting lever L can travel therein back and forth. Midway between the ends of the bar the intermediate wall of the selector plate has a cut-out portion as at M, so the lever may pass through.
This opening, or gate-way, is in such a position, relative to the cross lots N O, of the bars A B, that when the lever is in line with the gate-way, the slots N O are also in line, and in a neutral position, so that when a lateral motion is imparted to the lever L, and the rock-shaft F is moved longitudinally, the selector lever H will then engage with the other bar.
Speed Selectors.—The selector I, in Fig. 52, while made substantially the same in all cars, has a different order of lever movement. Each manufacturer has his own preferential type. In some cases the lever must be thrown forward in order to reverse, and in others it is drawn back.
In certain cars the lever is moved forwardly to throw the gears into first, or low, while a number of makers insist that the first movement should be to the rear.