The chain saw is also called a chain saw. It is a portable saw powered by a gasoline engine. It is mainly used for logging and timber production. Its working principle is to rely on the lateral movement of the L-shaped blades on the saw chain to perform the cutting action. Chain saws are generally divided into motorized chain saws and non-motorized chain saws. 1. The adjusting screw of the chain is behind the rotating shaft of the active machine of the chain saw. There is an adjusting screw between the chain and the bearing. Use a screwdriver to tighten clockwise and loose counterclockwise. 2. While adjusting the elastic screw, check the tightness of the chain. When the tension is appropriate, the chain can be pulled by hand when the chain is hanging on the lower part of the guide plate. 3. After adjusting the loosening screws of the loose chain, tighten the two fixing screws to prevent the loosening of the loosening screws of the chain.  Precautions 1. Always check the tension of the saw chain. When checking and adjusting, please turn off the engine and wear protective gloves. The proper tension is that when the chain hangs on the lower part of the guide plate, the chain can be pulled by hand. 2. There must always be a little oil spilled on the chain. Every time before work, the chain lubrication and the oil level of the lubricant tank must be checked. The chain can never work without lubrication. If you work with a dry chain, the cutting device will be damaged. Never use old motor oil. Old engine oil can not meet the lubrication requirements, not suitable for chain lubrication. 3. If the oil level in the oil tank does not decrease, it may be that the lubrication and transmission has failed. Should check the chain lubrication, check the oil circuit. Passing a contaminated filter can also lead to poor lubricant supply. The lubricating oil filter in the connecting pipe between the oil tank and the pump should be cleaned or replaced. 4. After replacing and installing a new chain, the saw chain needs 2 to 3 minutes of running-in time. Check the chain tension after running in, and readjust if necessary. New chains require more frequent tensioning than chains that have been used for a while. When cold, the saw chain must be attached to the lower part of the guide plate, but the saw chain can be moved on the upper guide plate by hand. If necessary, tighten the chain again. 5. When the working temperature is reached, the saw chain expands slightly and sags, and the drive joint at the lower part of the guide plate cannot be released from the chain slot, otherwise the chain will jump and the chain needs to be retensioned. The chain must be relaxed after work. The chain shrinks as it cools, and a chain that does not loosen will damage the crankshaft and bearings. If the chain is tensioned under working conditions, the chain will shrink when cooled, and over-tightening the chain will damage the crankshaft and bearings. 1/4" pitch saw chains