Open gear drive mechanisms, either uncovered or partially covered, predominantly employ involute gear transmission, and are widely used in large-scale rotating equipment such as crushers, dryers, and mining electric shovels. Despite numerous drawbacks compared to closed gear drives, open gear drives are still extensively used in industries like cement, metallurgy, and mining, even in developed countries in Europe and America. The reason lies in their good ventilation, lower processing difficulty, simple structure, and lower cost. However, open gear drives are susceptible to dust, debris, and moisture, leading to oil contamination, which can cause abrasive wear, pitting, and broken teeth.

Open Gear Drive Lube Method

In the early days, lubrication for open gear drives was primarily done manually by applying lubricant to the gear surfaces. Currently, the main methods of lubrication employed are immersion lubrication, idler wheel lubrication, and spray recirculation lubrication.

(1) Immersive Lubrication

Immersion lubrication involves filling the oil sump with lubricant and maintaining a certain oil level to allow the small gears or large gear ring to directly soak in lubricant for lubrication. For this type of lubrication, the protective cover for the drive gears must be tightly sealed to prevent lubricant leakage and dust intrusion. Since lubricant leakage through the sealed area of the gear cover is inevitable, regular lubricant replenishment is necessary to ensure reliable lubrication and prevent oil deficiency.

(Lubricating Sprocket)

Inertia wheel lubrication is a special form of immersion lubrication, where immersion lubrication involves directly submerging the teeth of small gears or large gear rings into oil. In contrast, inertia wheel lubrication transfers lubricant to the small gears through inertia wheels immersed in an oil bath. The advantages of this lubrication method are: only a small amount of lubricant is transferred to the gear surfaces, and only a minimal amount of lubricant participates in the oil circulation, thus minimizing the transfer of contaminated oil to the meshing surfaces.

(3) Spray Cycle Lubrication

Lubrication by oil recirculation involves using an external oil pump to deliver lubricant to the small gear. The advantage of this lubrication method over immersion lubrication is that it can evenly supply a small amount of lubricant to the gear surface, with almost no contaminants in the oil. However, only when the gear cover is extremely sealed can it prevent contaminants from the external environment from entering the oil tank, making the recirculation lubrication successful.

The lubrication method of the spraying cycle is divided into two types: continuous and intermittent. Currently, due to the requirements for machinery and equipment to meet energy-saving, environmental protection, and long service life, there is a need to develop high-performance open gear oils, which are typically enhanced with high-performance additives. For instance, extreme pressure anti-wear additives form a chemical reaction film on the metal surface, which has a residual effect. Once the film is formed, it can withstand multiple instances of wear, allowing for intermittent lubrication under certain conditions. From the specific operating conditions of open gears and the level of modern lubrication technology, the lubrication method for open gear drives should be: intermittent jet lubrication using high-performance open gear oils (greases).