Figure 2-5.-Clutch linkage.

Figure 2-3.-Cross section of a disc clutch. Figure 2-4.-Disc clutch operation. Figure 2-5.-Clutch linkage. 2-3 transmission transfers engine power from the clutch shaft to the propeller shaft and allows the operator to change the gear ratio between the engine and the rear wheels. Dual-ratio, or two-speed rear axles are often used on trucks. They have two gear ratios that can be chosen by the operator, usually by a manual control lever. A dual-ratio rear axle works the same as the auxiliary transmission; it doubles the number of gear ratios for driving the vehicle under the various loads and on different roads. The most common transmission type is the synchromesh transmission. The synchromesh transmission is basically a constant mesh, collar-shift transmission with an extra device, called a synchronizer, to equalize the speed of the mating parts before they engage. The synchronizer is used in all manual automotive transmissions and is common in other equipment where shifting while moving is required. Part of the prestart operation is to check the fluid level in the manual transmission. The normal level of lubricant is usually at the bottom of the filler plug opening. When lubricant is needed, you should always check the operator’s manual for the location and type of lubricant required for the transmission. When you keep the lubricant level correct, the gear teeth are protected, foam is reduced, and the transmission runs smoothly. Some transmission troubles that you may encounter and must document are as follows: l l l l l l Hard shifting Slipping out of gear No power through the transmission Transmission noisy when in gear Gear clash in shifting Oil leaks Manual Shift Operation Skill in manual shifting is a requirement of professional driving. Poor manual shifting results in poor vehicle performance and can cause vehicle damage. Know the gearshift lever positions so well that you can shift to any gear without looking at the shift lever. The gearshift pattern is usually diagramed in the vehicle or in the operator’s manual. Never move the gearshift lever from one position to another while the engine is running until you have fully depressed the