1. The sprocket should be mounted on the shaft without skewing or swinging. The end faces of two sprockets in the same transmission assembly should be in the same plane. When the center distance of the sprocket is below 0 and 5 meters, the allowable deviation is 1 mm; when the center distance of the sprocket is above 0 and 5 meters, the allowable deviation is 2 Mm. However, it is not allowed to cause friction on the side of the sprocket teeth. If the two wheels deviate too much, it is easy to cause off-chain and accelerated wear. When replacing the sprocket, care must be taken to check and adjust the offset.
的松紧度应适宜，太紧增加功率消耗，轴承易磨损；太松链条易跳动和脱链。 2. The tightness of the chain
should be appropriate. Too tight will increase the power consumption and the bearing will be easy to wear. Too loose chain is easy to jump and off the chain. The tightness of the chain is: lifted or depressed from the middle of the chain, the center distance between the two sprockets is about 2-3cm.
3. The new chain is too long or stretched after use, and it is difficult to adjust. Depending on the situation, the chain link is removed, but it must be an even number. The chain link should pass through the back of the chain, the locking piece is inserted outside, and the opening of the locking piece should face the opposite direction of rotation.
4. When the sprocket is severely worn, new sprocket and new chain should be replaced at the same time to ensure good meshing. It is not possible to replace a new chain or sprocket alone. Otherwise it will cause poor meshing and accelerate the wear of the new chain or new sprocket. After the tooth surface of the sprocket is worn to a certain extent, it should be turned over in time (refer to the sprocket used for adjustable surface). To extend the use time.
5. The old chain cannot be mixed with part of the new chain, otherwise it is easy to generate impact in the transmission and pull the chain off.
6. The chain should be filled with lubricating oil in time during the work. Lubricating oil must enter the mating clearance of the roller and inner sleeve to improve working conditions and reduce wear.
7. When the machine is stored for a long time, the chain should be removed and cleaned with kerosene or diesel, then coated with oil or butter and stored in a dry place to prevent corrosion. 
Visual inspection of the chain
1. Whether the inner / outer chain is deformed, cracked or embroidered
2. Whether the pin is deformed or turned, embroidered
3. Whether the roller is cracked, damaged or excessively worn
4. Whether the joint is loose or deformed
5. Is there any abnormal noise or abnormal vibration during operation, and is the chain lubrication condition good?
The chain length accuracy should be measured according to the following requirements:
1.The chain is washed before measurement
2. Enclose the chain to be tested on two sprockets, and the upper and lower sides of the chain to be tested should be supported.
3. The chain before measurement should stay for 1 min under the state of one-third applied and minimum ultimate tensile load.
4. During the measurement, apply the specified measurement load on the chain to tension the upper and lower chains, and ensure that the chain is properly engaged with the sprocket.
5.Measure the center distance between two sprockets
Measuring chain elongation:
1. In order to remove the clearance of the entire chain, it is necessary to measure under a state of pulling tension on the chain
2. When measuring, in order to minimize the error, measure at 6-10 places
3. Measure the inner L1 and outer L2 dimensions between the rollers of the knots to find the judgment size L = (L1 + L2) / 2
4. Calculate the elongation length of the chain. This value is compared with the limit value of the chain extension used in the previous item.
Chain structure: It consists of inner and outer links. It consists of five small parts: inner link plate, outer link plate, pin, sleeve, and roller. The quality of the chain depends on the pin and sleeve. 
Before the car with the rear dial hits the chain, it moves the chain to the smallest wheel to the smallest wheel. This way, the chain is loose, easy to operate, and it is not easy to "bounce" after being cut off.
After cleaning and refueling the chain, slowly reverse the chainring, and the chain links coming out of the rear dial should be able to be straightened. If some chain links still maintain a certain angle, it means that it does not move smoothly and belongs to a knot. Adjustment. Damaged chain links must be replaced in a timely manner. It is recommended that the maintenance chain strictly distinguish three types of pins and use connecting pins.
Pay attention to the straightness when using the chain beater, so it is not easy to skew the thimble. Careful use of tools can both protect the tools and achieve good results. Otherwise, the tools will be easily damaged, and the damaged tools will more easily damage the parts, which is a vicious circle.