汽车专业英语 教学课件 ppt 作者 廖忠诚 杨晓波 主编Chapter5 Transmissions.ppt

chapter 5 transmissions yanganjie 5.1 Clutch when placing the transmission into gear, - the transmission input shaft must be disconnected from the engine. when moving the vehicle from rest, - slowly releasing the pedal, gives a gradual engagement of the drive, as the friction facings slip and allow torque to be applied progressively until both units are rigidly connected. when selecting an alternative ratio, that is, changing gears, when the vehicle is in motion - the transmission of engine torque must again be interrupted for this to occur. and, when bringing the vehicle to a halt, - the transmission must be disengaged to leave the engine running at its idling speed. 5.1.4 Operating mechanisms The clutch operating mechanism may be mechanical or hydraulic(Fig.5-3). Mechanical systems may use a system of levers but cable operation gives more flexibility and is more common. This is a cable-operated control for a front-wheel drive vehicle. The outer cable is fixed to the pedal box inside the vehicle and to the clutch housing in the engine compartment. The inner cable connects between the upper end of the clutch pedal and an external lever on top of the clutch housing. This lever is connected to a vertical shaft, supported in the housing and attached internally to a release fork, which carries the release bearing. 5.1.5 Pressure plate In light vehicle applications the pressure plate is normally a diaphragm type and is serviced as an assembly (Fig.5-4). It consists of a pressed steel cover, a pressure plate with a machined flat surface, a number of spring steel drive straps, and the diaphragm spring. This diaphragm is located inside the clutch cover on 2 fulcrum rings, held by a number of rivets passing through the diaphragm. The pressure plate is connected to the cover by the spring steel drive straps, riveted to the cover at one end, and to projecting lugs on the plate, at the other. Retraction clips hold the pressure plate in contact with th