Fig. 109. Friction Transmission
The Planetary Type of Transmission.—The planetary type of transmission made its appearance along about the same time as the friction type. The power is transmitted to the load through a set of reduction gears arranged in a drum. A king gear on the engine shaft operates a set of small gears in the drum. These small gears reduce the leverage speed and transmit the power to the drive shaft, a band similar to that used on brakes is fitted to the face of the drum. When this drum containing the reduction gears is not in use it turns at crank shaft speed. The speed is used by pressing a foot pedal which tightens the brake band and holds the drum stationary, thereby forcing the smaller gears into action.
Planetary transmissions are shown and fully explained in a later chapter. (See [Model T Ford Supplement].)
The Sliding Gear Transmission.—This type of transmission has proved very successful, and is used by 98 per cent of the present day automobile manufacturers. This type of transmission made its first appearance with a progressive gear shift, that is, it was necessary to proceed through one speed or set of gears to engage the next. This arrangement caused considerable confusion at times, as it was necessary to reshift the gears back through these speeds to attain neutral, when the car was brought to a stand still.
| Neutral | ||||
| 2nd. | Rev. | Rev. | ||
| 2nd. | ||||
| Neut. | ||||
| 1st. | ||||
| 3rd. | ||||
| 3rd. | 1st. | |||
| Ball-and-Socket Shift | H or Gate Type Gear Shift | |||
Fig. 110. Selective Type of Gear Shifts
Fig. 111. Sliding Gear Transmission—Sectional View
The control lever operated on a straight forward and backward direction on a quadrant, having a notch for each speed change. This gear shifting arrangement has also been abandoned by manufacturers in favor of the selective gear shift which is arranged so that the driver may choose any speed at will. [Fig. 110] shows the control lever which operates in a frame resembling the block letter H and the ball and socket shift which operates in the same manner. [Fig. 111] shows the complete assembly of the selective sliding gear transmission. The sliding gears are arranged on a separate core and are operated by an individual throw fork, which seats in a groove on the shoulder of the gear. Low and reverse are always opposite each other on the same core. High and intermediate are located on another core, and are controlled by another individual shifting fork. The gear box arrangement ([Fig. A]) shows the cast gear box which contains the gears, shafts, and bearings, and a roomy compartment below the gears in which grease is carried, as the gears in this type of transmission always operate in an oil bath which prevents excessive wear and causes them to operate noiselessly. [Fig. B], the gear case cover, contains the slotted sliding shafts, to which the gear in shifting forks are attached. [Fig. C] shows the arrangement of the gears in the case and explains their operation. Gear No. 1 is attached to the extreme end of the engine shaft, and is continually engaged with gear No. 4, which causes the counter shaft No. 11, containing the stationery gears, to revolve whenever the engine shaft No. 9 is in operation. The drive shaft No. 8 does not run straight through and connect with No. 9, the engine shaft, but ends and takes its bearing in the core of gear No. 1. Consequently, when the gears on the drive shaft are slid into mesh with the gears on the counter shaft, variable speeds are attained. Low speed is obtained by sliding gear No. 3 into mesh with gear No. 6; second or intermediate is obtained by meshing gears No. 2 and gear No. 5.