【正文】 e transmission. Smooth engagement is ensured by slipping of the disk before a full pressure is applied.The automobiles are equipped with a dry springloaded clutch. The clutch is termed dry because the surfaces of the pressure plate and driven disks are dry incontrast to oilbath clutches in which the plate and disks operate in a bath of oil. It is called springloaded because the pressure plate and the driven disk are always pressed to each other by springs and are released only for a time to shift gears or to brake the automobile.In addition to the plate and disk, the clutch includes a cover, release levers, a release yoke, pressure springs and a control linkage. The clutch cover is a steel stamping bolted to the flywheel. The release levers are secured inside the cover on the supporting bolts. The outer ends of the release levers are articulated to the pressure plate. Such a construction allows the pressure plate to approach the cover or move away from it, all the time rotating with the flywheel. The springs spaced around the circumference between the pressure plate and the clutch cover clamp the driven disk between the pressure plate and the flywheel.The springs are installed with the aid of projections and sockets provided on the cover and pressure plate. The pressure plate sockets have thermalinsulation gaskets for protecting the springs against overheating.The clutch release mechanism can be operated either mechanically or hydraulically. The mechanicallyoperated release mechanism consists of a pedal,a return spring, a shaft with lever, a rod, a release yoke lever, a release yoke, a release ball bearing with support and a clutch release spring. When the clutch pedalis depressed, the rod and shaft with yoke shift the released bearing and support assembly. The release bearing presses the inner ends of the release levers, the pressure plate is moved away from, the driven disk and the clutch is disengaged. To engage the clutch, the pedal is released, the release bearing thus releasing the release levers so that the pressure plate is forced by its springs towards the flywheel to clamp the driven disk and engage the clutch.The clutch hydraulicallyoperated release mechanism consists of a clutch pedal, clutch release spring, a main cylinder, a pneumatic booster, pipelines and hoses and a lever of the clutch release yoke shaft. The main cylinder acmodates a piston with a cup. The pneumatic booster serves to decrease the pedal force required to disengage the clutch. The booster includes two housings with the servo diaphragm clamped in between. The housing acmodates pneumatic, hydraulic and servo plungers. When the clutch pedal is pushed, the fluid pressure from the main cylinder is transmitted through the pipelines and hoses to the hydraulic and servo plungers of the pneumatic booster.The servo arrangement is intended for automatic change of the air pressure in the pneumatic cylinder proportionally to the force applied to the pedal. The plunger moves with the diaphragm, the outlet valve closes and the inlet valve opens thus admitting the pressed air to the pneumatic plunger piston. The forces created by the pneumatic and hydraulic plungers are added together and are applied through the push rod to the release yoke shaft lever, the lever turns the shaft and the release yoke shaft disengaging the clutch. After the clutch pedal is released,the outlet valve opens and the inlet closes. Under the action of the springs thepistons return the plungers to the initial position and the air from the cylinder is let out to the atmosphere. Automatic clutches were used in certain . and European cars. American MotorsEstick clutch eliminated the need for physical operation of the clutch pedal. A German car maker engineered an automatic clutch system called Hydrak, which consisted of a fluid flywheel connected to a single, dry disk clutch.In the EStick set up, the pressure plate levers engage the clutch disk rather than release them. Also, the clutch remains disengaged until a servo unit is applied by oil pressure when the shift lever is placed in gear with the engine running.The Hydrak unit also begins operation when the lever is in gear. This activates a booster unit, which disengages the clutch disk. The hydraulic clutch parts are bridged over by a freewheel unit, which goes in