The selection of cardan shaft can be divided into single constant load, pulsating load, or two-way alternating load according to the type of transmission load. When disassembling the connecting bolts of universal joint, it is difficult to disassemble the bolts due to a layer of oil dirt, corrosion products and other deposits deposited on the thread surface. It is very difficult to disassemble the bolts with serious corrosion or damage. When tightening or loosening the bolt, it can make the bolt stronger and not easy to slip. For bolts that have been rusted or have more oil stains, they are often washed with solvent, and then soaked in kerosene with cotton yarn, and then placed at the joint of bolts and nuts to let kerosene seep into the threads, which will make it easier to disassemble.
If the bolt cannot be removed, the heating method is adopted. The heating temperature is generally below 200 ℃. The gap between the nut and the bolt is increased by heating, and the rust is easy to fall off, making the bolt removal easier. Large-scale boiler feed pump adopts speed-regulating hydraulic coupling, which can regulate flow well and reduce power consumption. The universal coupling has a strong bearing capacity. Compared with other types of couplings with the same rotating diameter, the torque transmitted by the universal coupling will be larger. Mechanical equipment with limited rotating diameter can be used.
The universal coupling uses high-strength bolts and self-locking nuts to connect the flanges at both ends to other mechanical components, and its transfer torque is transmitted through the friction force between the flange end keys and flanges. Hydraulic expansion method and thermal expansion method are usually used for the installation of universal coupling. The thermal expansion method is to immerse the hub of the coupling in the high point heat transfer oil, or use the oven hot gas or steam heating to make the hub reach a certain temperature and obtain the required expansion. The expansion amount should be the sum of the interference value required by the assembly and the clearance required by the actual assembly, so that the mating surface of the hub and the shaft cone will not be scratched, The bearing capacity of thermal expansion method after assembly is higher than that of pressing method.