KIT- 20R3368 - Caterpillar

Illustration 3 g01085112
Sliding gear transmissions have many variations. The sliding gear transmissions often provide as many as ten forward speeds and two reverse speeds.Illustration 3 shows the D6C Sliding Gear transmission. The positions of the three parallel shafts in the transmission can be seen at the right end. The transmission upper shaft (input shaft) is connected to the engine through a flywheel clutch. The countershaft is at the right and the output shaft is at the bottom of the transmission.The two shift levers, which the operator uses to change gears, are the forward and reverse lever (in back) and the speed shift lever.Gear Shift Mechanism
Illustration 4 g01085114
Illustration 4 shows a manual transmission with the shift controls removed. The shift controls are used to change gear positions. In sliding gear, collar shift, and synchromesh transmissions, the gears or collars are moved by means of a shifter fork which fits in a groove in the collar or gear. This fork is connected to the gearshift lever and moved manually by the gearshift lever. The gearshift lever reaches directly into the transmission from the operator's platform.The forward and reverse shifting fork is the single fork (1) at the top. The other three forks move the speed gears. The input shaft and the forward/reverse sliding gear are visible inside the case (at the top.)The shifter forks, which slide the gears or collars, are attached to the gearshift rails or shafts. The gearshift lever has a ball that fits into a socket in the top of the transmission cover. This permits swiveling of the gearshift lever into the various shift positions. Movement of the lever causes the finger on the lower end to select and move one of the rails, the forks, and a gear or collar.For example, in a four-speed transmission, as the gearshift lever is moved from NEUTRAL (N) to the left, the finger on the lower end of the lever moves into the slot in the low and second speed rail. This action selects the rail, forks, and gears in order to be moved. Then, as the lever is pushed forward into low speed, the rail assembly is pushed toward the rear. Then the low gear is engaged.A locking system must be used in order to hold the shift rail in position and to prevent other rails from moving. The shift rails contain spring-loaded detent balls that drop down into undercuts on the rails as the rails are moved into the various shift positions. This holds the gears in mesh.Input Shaft
Illustration 5 g01085115
A model will be used to illustrate how the sliding gear transmission works.The first components of the model (Illustration 5) are an input shaft or upper shaft that are cranked by the engine and a forward and reverse sliding gear. The drive shaft and gear turn with the engine when the clutch is engaged. The forward and reverse sliding gear is splined to the input shaft. The input shaft and gear turn together and the gear can slide back and forth.