Hüdroautomaatkäigukasti

Hüdroautomaatkäigukast, often referred to as an automatic transmission, is a type of motor vehicle gearbox that automatically changes gear ratios as the vehicle moves, freeing the driver from having to shift gears manually. The most common type of automatic transmission is the hydraulic automatic transmission.

A hydraulic automatic transmission uses a planetary gearset, hydraulic control system, and a torque converter to achieve automatic gear changes. The torque converter replaces the clutch found in manual transmissions, allowing the engine to remain running while the vehicle is stopped. It consists of a pump impeller, a turbine, and a stator, all housed within a fluid-filled casing. Hydraulic fluid is used to transmit power from the engine to the transmission.

The hydraulic control system directs pressurized fluid to engage and disengage different clutch packs and brake bands within the transmission. These clutches and bands, in turn, lock and unlock various components of the planetary gearset, creating different gear ratios. Sensors monitor factors such as vehicle speed, engine load, and throttle position to determine when a gear change is necessary.

The operation is smooth and seamless, as the torque converter can slip, allowing for gradual engagement and preventing stalling. Modern hüdroautomaatkäigukastid also incorporate electronic control units (ECUs) that optimize shift points for fuel efficiency and performance. While historically less fuel-efficient than manual transmissions, advancements have significantly narrowed this gap. They are prevalent in many passenger vehicles due to their ease of use and comfort.