What is the function of hydraulic transmission oil?
3 Answers
Hydraulic transmission oil is the hydraulic medium used in hydraulic systems that utilize liquid pressure energy. It plays roles in energy transmission, wear resistance, system lubrication, corrosion prevention, rust prevention, and cooling within the hydraulic system. Hydraulic transmission oil is a high-quality hydraulic oil. The oil used as a transmission medium in hydraulic systems is called hydraulic oil, also referred to as hydraulic transmission oil or hydraulic fluid. Hydraulic transmission oil is an indispensable transmission medium in hydraulic systems. To meet transmission requirements, it must first have good viscosity-temperature characteristics. Within the operating temperature range, the oil's viscosity should change minimally with temperature, meaning it should have a high viscosity index. Additionally, it should possess excellent lubricating properties. Hydraulic oil not only serves as an energy transmission medium but also as a lubricant for mechanical movement. Good lubricity ensures the normal operation of machinery. A high-quality hydraulic transmission oil should also be pure, free from mechanical impurities, and non-corrosive. Moreover, it should resist oxidation, minimizing or avoiding the formation of oxides when temperatures rise, which can accelerate oil degradation and clog oil passages.
Hydraulic transmission fluid is indeed the lifeline of an automatic transmission. It first transfers engine power in the torque converter, acting like a diligent courier delivering energy to the gear sets. Additionally, it lubricates gears and bearings to reduce friction damage, while the heat generated during operation is entirely dissipated through fluid circulation. As a seasoned car owner, I've witnessed many friends neglect fluid changes—degraded oil leads to jerky gear shifts like riding a horse, and in severe cases, completely ruins the transmission. Fresh fluid replacement is required every 40,000 kilometers, with specific grades like DEXRON or MERCON series tailored to different models. Never mix types or substitute with engine oil as a stopgap.
In auto repair shops, transmission failures are often caused by transmission fluid issues—about 80% of the time. This fluid must maintain hydraulic pressure to drive the turbine in the torque converter while staying clean to prevent sludge buildup that clogs solenoids. Last month, an Audi with gear slippage was disassembled, revealing blackened fluid with metal shavings—a clear case of wear due to overdue fluid changes. We recommend owners develop a habit of changing it every two years or 50,000 km. When selecting fluid, check the manufacturer-approved specifications, and pay attention to temperature adaptability—viscosity shouldn’t drop under summer heat.
