Open gear drive mechanisms, often 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 prone to contamination by dust, debris, and moisture, leading to abrasive wear, pitting, and broken teeth.

Open Gear Drive Lube Methods

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

(1) Immersive Lubrication

Immersive lubrication involves filling the oil sump with lubricant to maintain a certain oil level, allowing the small gears or large sprockets to directly soak in the lubricant for lubrication. For this type of lubrication, the gear cover must be tightly sealed to prevent lubricant leakage and dust intrusion. Since lubricant leakage through the seal of the gear cover is inevitable, regular lubricant replenishment is necessary to ensure reliable lubrication and prevent oil shortage.

(2) Sprocket lubrication

Inertia wheel lubrication is a special form of immersion lubrication, where immersion lubrication involves the teeth of small gears or large sprockets being directly immersed in oil. Inertia wheel lubrication, however, transfers the 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 small quantity of lubricant participates in the oil circulation, thus minimizing the transfer of contaminated oil to the meshing surfaces.

(3) Spray Cycle Lubrication

Lubrication by spraying circulates lubricant to the small gears using an external oil pump. The advantage of this method over immersion lubrication is that it can evenly distribute a small amount of lubricant to the gear surface with almost no contaminants. However, only when the gear cover is extremely tight can it prevent external contaminants from entering the oil reservoir, making the circulation lubrication successful.

The oil circulation lubrication method is further divided into continuous and intermittent types. Currently, due to the requirements for machinery and equipment to meet energy-saving, environmental protection, and long service life, there is a demand for the development of high-performance open gear oils, which typically contain high-performance additives. For example, extreme pressure anti-wear additives generate a chemical reaction film on the metal surface, which has a residual effect and can withstand multiple wearings after forming the film once, allowing for intermittent lubrication under certain conditions. From the specific working conditions of open gears and the modern lubrication technology level, the lubrication method for open gear drives should be: intermittent jet lubrication using high-performance open gear oils (greases).