The transmission consists of the shell, transmission part and operation part.
(1) Shell: The shell is the foundation for the installation and support of all parts of the transmission and storage of lubricants. There are bores for mounting the bearings on it. The transmission is subjected to variable load, so the shell should have sufficient rigidity, the inner wall is reinforced, the shape is complex, mostly castings (material is gray cast iron, commonly used HT200).
In order to facilitate installation, the transmission part and manipulation part is often made into a split type, the box cover and shell with bolts and reliable positioning. Shell with oil, oil drain, oil surface check dipstick mouth, should also consider heat dissipation.
(2) transmission part: refers to gears, shafts, bearings and other transmission parts. The geometric size of the shaft is determined by strength and stiffness calculation. Because the main decision on the stiffness, and carbon steel and alloy steel modulus of elasticity is nearly equal, so the general use of carbon steel (commonly used 45 steel). Only gears and shafts made of one piece or shaft load is serious to use alloy steel. Shaft and gears are mostly spline coupling (good alignment, reliable transmission of power, small extrusion stress, etc.). The spline part of the shaft and the bearing place are surface quenched. Shaft mostly with rolling bearing support, simple lubrication, high efficiency, small radial clearance, axial positioning should be reliable. Lubrication method mostly with splash (υ>25m/s, as long as the viscosity is appropriate can be thrown to the wall).
(3) manipulation part: the main parts are located in the transmission cover. (1) can reduce the number of gears, and the more gears to reduce the number of advantages more obvious. Compared with the simple transmission, it can shorten the length of the shaft, reduce the external size and weight of the whole transmission, and can easily get more than one reverse gear. Therefore, when the number of forward gears exceeds six, almost all of them are used in component transmissions.
