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1、1. Hydraulic Fundamentals2. Torque ConverterBASIC THEORYChonan TSTCCONTENTSChonan TSTC2Up to this point, the basic mechanics of the KM170 were highly emphasized. Now that gears and frictional units have been thoroughly discussed, its time to investigate the hydraulic systems of the transaxle. These
2、systems or circuits are very important for correct operation of the transaxle. Without the hydraulic circuits present in the transaxle, none of the components could combine to produce motion, nor could the transaxle function automatically. The transaxle is lubricated, cooled, shifted and connected t
3、o the engine by means of a fluid. Without hydraulic oil in the transaxle, none of these tasks could be performed satisfactorily. Therefore, it is imperative to learn the basics of hydraulic fundamentals before clutch and band application or hydraulic charts can be investigated thoroughly. 90% of all
4、 automatic transaxle failures can be diagnosed using hydraulic charts. If the understanding of hydraulic fundamentals is not complete, then these charts would be of little value to the service technician. HYDRAULIC FUNDAMENTALSChonan TSTC3In the early seventeenth century, Pascal, a French scientist,
5、 discovered the hydraulic lever. Through controlled laboratory experiments, he proved that force and motion could be transferred by means of a confined liquid. Further experimentation with weights and pistons of varying size, Pascal also found that mechanical advantage or force multiplication could
6、be obtained in a hydraulic pressure system, and that the relationships between force and distance were exactly the same as with a mechanical lever.From the laboratory data that Pascal collected, he formulated Pascals Law, which states : “Pressure on a confined fluid is transmitted equally in all dir
7、ections and acts with equal force on equal areas.” This law is a little complex to completely understand as it stands right now. The following illustrations and explanations break down each concept and discuss them thoroughly enough for easy understanding and retention.HYDRAULIC FUNDAMENTALSPASCALs
8、LawChonan TSTC4HYDRAULIC FUNDAMENTALSPASCALs Law10 kgf100 kgfArea : 1m2Area : 10m2P1=10kgf/m2Hydraulic fluidChonan TSTC5ForceA simplified definition of the term force is : the push or pull exerted on an object. There are two major kinds of forces : friction and gravity. The force of gravity is nothi
9、ng more than the mass, or weight of an object. In other words, if a steel block weighing 100 kg is sitting on the floor, then it is exerting a downward force of 100 kg on the floor. The force of friction is present when two objects attempt to move against one another. If the same 100 kg block were s
10、lid across the floor, there is a dragging feeling involved. This feeling is the force of friction between the block and the floor. When concerned with hydraulic valves, a third force is also involved. This force is called spring force. Spring force is the force a spring produces when it is compresse
11、d or stretched. The common unit used to measure this or any force is the kilogram (kg), or a division of the kilogram such as the gram (g).HYDRAULIC FUNDAMENTALSForce and Pressure RelationshipsChonan TSTC6PressurePressure is nothing more than force (kg) divided by area (m2), or force per unit area.
12、Given the same 100kg block used above and an area of 10m2 on the floor ; the pressure exerted by the block is : 100kg/10m2 or 10kg per square meter.HYDRAULIC FUNDAMENTALSForce and Pressure RelationshipsPressure On a Confined Fluid Pressure is exerted on a confined fluid by applying a force to some g
13、iven area in contact with the fluid. A good example of this would be if a cylinder is filled with a fluid, and a piston is closely fitted to the cylinder wall having a force applied to it, thus, pressure will be developed in the fluid. Of course, no pressure will be created if the fluid is not confi
14、ned. It will simply “leak” past the piston. There must be a resistance to flow in order to create pressure. Piston sealing, therefore, is extremely important in hydraulic operation. The force exerted is downward (gravity) ; although, the principle remains the same no matter which direction is taken.
15、Chonan TSTC7The pressure created in the fluid is equal to the force applied ; divided by the piston area. If the force is 100 kg, and the piston area is 10m2, then pressure created equals 10kg/m2 = 100kg/10m2. Another interpretation of Pascals Law is that : “Pressure on a confined fluid is transmitt
16、ed undiminished in all directions.” Regardless of container shape or size, the pressure will be maintained throughout, as long as the fluid is confined. In other words, the pressure in the fluid is the same everywhere. The pressure at the top near the piston is exactly same as it is at the bottom of the container, thus, the pressure at the sides of the container is exactly the same as at top and bot
