What is the working principle of an automatic transmission oil pump?
4 Answers
Automatic transmission oil pump works by providing hydraulic oil with certain pressure and flow for the torque converter and hydraulic control system, while ensuring lubrication needs for friction parts such as planetary gear mechanisms. Below are some details about automatic transmission oil pumps: 1. Installation location: The automatic transmission oil pump is usually installed behind the torque converter and is driven by the shaft sleeve at the rear end of the torque converter housing. In the oil supply system of an automatic transmission, there are two types of oil pumps: fixed displacement pump and variable displacement pump. 2. Fixed displacement pump: Common fixed displacement pumps include internal gear pumps, rotor pumps, and vane pumps, with internal gear pumps being the most widely used. The internal gear pump mainly consists of an external gear, internal gear, crescent-shaped partition, pump housing, and pump cover. The gears are tightly fitted in the pump's inner cavity, with the external gear as the driving gear and the internal gear as the driven gear, separated by the crescent-shaped partition. 3. Variable displacement pump: The oil delivery volume of a variable displacement pump stops increasing after the engine speed exceeds a certain value, thereby reducing the operating resistance of the oil pump at high speeds and improving the vehicle's fuel economy.
The oil pump plays a crucial role in an automatic transmission. It is directly driven by the engine through the torque converter or input shaft, starting to work as soon as the vehicle moves. The specific principle is that the engine generates power, driving the gears or vanes inside the oil pump to rotate, sucking transmission fluid from the oil pan and then compressing and pressurizing it. This high-pressure oil is delivered to various parts of the transmission system to actuate clutches and brakes for gear shifting, ensuring a smooth and jerk-free shifting process. If the oil pump is worn or the oil is too dirty, causing insufficient pressure, you may experience delayed shifting, strong impact sensations, and in severe cases, transmission overheating or even failure. I recommend checking the pump's condition every 50,000 kilometers when changing the oil. New cars use high-efficiency designs, but the basic principle remains the same—neglecting maintenance will cost you dearly.
Speaking of the automatic transmission oil pump, I think of it as an invisible assistant that starts working as soon as the engine is turned on. Simply put, the engine's power connects to the pump, driving internal components to rotate, suck in oil, and pressurize it. This pressure then pushes the oil to operate components like the clutch, enabling smooth gear shifts. You might not notice it while driving, but if it malfunctions—say, due to pump wear or dirty oil—the car will experience jerky gear shifts and poor acceleration. Once on a long drive, I encountered a similar issue; a check at the repair shop revealed a clogged oil pump, and changing the oil fixed it. Don’t overlook regular transmission fluid checks in daily use—it extends lifespan and saves fuel. Modern designs are more durable, but maintenance remains key.
The core working principle of the oil pump is that the engine drives it to pump and pressurize oil, lubricate, and control shifting actions. The engine connects to the pump, where gears or vanes rotate to suck in, compress, and pressurize the oil, then deliver it to the transmission internals. During maintenance, I always advise car owners to change the transmission oil regularly to prevent the oil pump from sticking or wearing out. Insufficient pressure can affect shift smoothness, so early inspection helps avoid major repairs. Simple maintenance can keep the car running longer.
