When the clutch is separated, when the clutch handle is held by the left hand, the clutch wire rope is pulled to drive the shift lever to move and drive the pressing block to press on the support plate. The support disk compresses the compression spring, and the pressure on the driving disk, the driving disk and the friction plate disappears immediately. They are in a free state respectively, and the end faces are not subjected to any pressure, so that the friction between each friction plate and the driving plate rotating together disappears. In this way, the driven part does not rotate with the engine crankshaft, and the clutch is in a disengaged state. When the clutch handle is released, the compression spring compresses the driving disk, the driving disk and the friction plate, and the clutch is soft-engaged. Qingqi 15 mopeds and Happiness 250 motorcycles all adopt the working principles of flat disc friction clutch and automatic centrifugal clutch.
The working principle of automatic clutch is that the centrifugal force generated when the driving disk rotates is in frictional contact with the moving disk, which generates friction to transmit torque. It is mainly composed of driving disk, centrifugal throwing block, buffer apron, tension spring, pin, pin and so on. The inner hole of the centrifugal throwing block is movably matched with the pin shaft, and the centrifugal throwing block can swing around the pin shaft, and the tension spring always pulls the centrifugal throwing block to the minimum arc size. They are all installed on the driving disk, which is fixed with the crankshaft of the engine, and the rotation of the crankshaft drives the driving disk to rotate. The driven plate is sleeved on the crankshaft, and the driven plate and the crankshaft can rotate relatively freely through bearings.
The inner diameter of the driven disk is larger than the diameter of the driving disk composed of three centrifugal throwing blocks. When the three centrifugal throwing blocks are not thrown out, the driving plate and the driven plate are not engaged, and the automatic centrifugal clutch is in a separated state. When the engine speed is higher than 1, 600 rpm, the three centrifugal throwing blocks on the driving plate overcome the tension of the spring under the action of centrifugal force and swing in the centrifugal direction around the pin axis respectively. So that the diameter of the excircle formed by them increases, and the excircle is pressed against the inner circular surface of the driven plate to generate friction force, which drives the driven plate to rotate, and the clutch is in an engaged state. When the engine speed is less than 1 600 rpm, the centrifugal force of the three centrifugal throwing blocks on the driving disk is less than the tension of the three springs, and they return to their original positions under the tension of the springs. At this time, the clutch is disengaged, and the driving disc rotates with the engine crankshaft, while the driven disc is stationary. The automatic centrifugal clutch is in the disengaged state again.
It can be seen that the engagement and disengagement of the centrifugal clutch are completely controlled by the engine speed. When the engine reaches a certain speed, the clutch will automatically engage; Otherwise it will separate automatically. So it is called automatic centrifugal clutch. Both Jialing CJ60 moped and Happiness 50 moped adopt automatic centrifugal clutch.