Reversing.—When the car is not running the gears G H are always in a neutral position, as shown in Fig. 41, and in order to reverse shaft B, the lever P, is drawn back, as shown in Fig. 44, so that the small gear O, will engage with the large and the small gears H M, respectively. The result is, gear H, is reversed, and this reversal can take place only when the two gears G H are in a neutral position.
The term progressive takes its name from the motion of the control lever involved in changing the gears. It proceeds regularly from the lowest to the highest.
Selective Type.—The second method, the selective, enables the operator to select any speed at will, and in doing so, it is not necessary to go through the other speeds to reach the high or the low, as is the case with the progressive.
Where there are only three speeds forward, and one in reversing, this is not so material, but as the better class cars have four speeds forward, it means that in order to reach high the gear in a progressive system must go through two intermediate speeds.
The shaft B, Fig. 47, which connects with the engine through a clutch, has its end journaled in a driven shaft A, and a gear C is fixed to the shaft B, and provided with a recessed side. This has internal teeth to receive the teeth of a sliding gear D. Another, smaller, sliding gear E is also on the shaft.
Fig. 47. Selective Transmission. Low Gear.
Below the shafts A B is a shaft F, which carries a gear G, about half the diameter of the gear C, with which it is constantly in engagement. This shaft, further, has a gear I, the same diameter as the gear D, with which it meshes, and the shaft also carries a gear K, smaller than gear J.
Behind the gear K is an idler pinion L, in such position that it may be slid into contact with K, and the gear E, on shaft B, is also adapted to be meshed with the pinion L by sliding contact.
All the gears G I J K are keyed to the shaft F, and only the gears D E and L are capable of being shifted.