QJS - D560 - 3C - 25 is a hard-tooth surface reducer in the QJ series. It is often used in heavy-load scenarios such as cranes. It is often lubricated by oil pool immersion. A reasonable oil pool depth is generally 1-2 tooth heights for large gears. If the depth of the oil pool is too shallow or too deep, it will shorten its service life by destroying the lubrication effect, exacerbating component wear, and deteriorating the oil. The specific effects are as follows:
The oil pool is too shallow: insufficient lubrication causes all-round wear
1. Premature failure of gears: If the oil pool is too shallow, the gears will not be immersed in enough oil, making it difficult to form a continuous and stable oil film on the tooth surfaces. Boundary friction or even dry friction will easily occur when the gears mesh. This will accelerate tooth surface wear and pitting corrosion. In the long run, it will also cause serious failures such as tooth surface gluing and tooth breakage. Moreover, a shallow oil pool means a small amount of oil, which cannot effectively take away the heat generated by meshing. Local high temperatures will further destroy the stability of the oil film, while reducing the performance of the gear material and greatly shortening the service life of the gear. In addition, if the oil pool is too shallow, it is easy for the gears to stir up the sludge and metal debris deposited on the bottom of the box. These impurities enter the meshing area and act like abrasives to aggravate gear wear.
2. The risk of bearing damage increases sharply: The heavy-duty bearings matched with this type of reducer rely on splash lubrication. When the oil pool is too shallow, the oil splash height and range are insufficient, and the bearing raceways and rolling elements are difficult to be covered by oil, and an effective oil film cannot be formed. Bearings will run in an oil-starved state, which will not only produce high-frequency abnormal noises, but also cause serious wear, raceway peeling and other problems, eventually leading to bearing jamming and forcing the equipment to shut down. If not handled in time, shaft components may also be damaged.
3. Premature aging of seals: The local high temperature caused by insufficient lubrication will be transmitted to the box seal. If the seal is exposed to a high temperature environment for a long time, the material will gradually become brittle, harden, and lose elasticity, leading to seal failure and oil leakage problems. Oil leakage will further reduce the amount of oil, forming a vicious cycle of 'worse lubrication - higher temperature - more serious oil leakage', accelerating damage to the entire machine.
The oil pool is too deep: excessive oil stirring causes multiple losses
1. The gear transmission efficiency decreases and the loss increases: The large gear of this type of reducer is large in size and has strong rotational inertia. If the oil pool is too deep, the oil in the large gear will exceed the standard. When the gear rotates at high speed, it needs to overcome huge oil resistance. Stirring the oil violently will not only cause a large amount of energy loss, but also cause a large number of bubbles to be mixed into the oil. When bubbles enter the meshing area and rupture, they will cause cavitation damage and destroy the integrity of the tooth surface; at the same time, the turbulent impact caused by oil churning will also aggravate gear surface fatigue, which may easily lead to gear cracks in the long run.
2. Excessive oil temperature will deteriorate the oil and damage components: excessive oil stirring will convert a large amount of mechanical energy into thermal energy. When the oil pool is too deep, the total amount of oil is large, convection is poor, and heat is difficult to dissipate, causing the oil temperature to continue to rise and easily exceed the critical temperature of 90°C. High temperature will accelerate the oxidation and deterioration of lubricating oil, causing its viscosity to decrease and its lubrication performance to be greatly reduced, making it unable to meet the lubrication needs under heavy load conditions. In addition, high temperature will also cause slight thermal deformation of the box, destroy the gear meshing accuracy and bearing clearance, and further aggravate the abnormal wear of gears and bearings.
3. Seal leakage and component corrosion: If the oil pool is too deep, the oil will exert greater pressure on the inside of the box. Coupled with the fluctuation impact caused by oil stirring, the seal will bear excessive pressure and oil leakage from the sealing gap will easily occur. At the same time, the oxidation of oil at high temperatures will generate acidic substances. Excessive oil will cause acidic substances to accumulate in the box. These acidic substances will corrode the metal surfaces inside the box that are not completely covered by the oil film, as well as the non-meshing parts of gears and bearings. Long-term corrosion will weaken the strength of components and increase the risk of failure.
