tågväxellåda

A tågväxellåda, often translated as a train gearbox or transmission, is a crucial component in many diesel-electric and diesel-hydraulic locomotives. Its primary function is to transmit power from the diesel engine to the driving wheels, allowing the locomotive to start moving and achieve varying speeds. The need for a tågväxellåda arises because diesel engines operate most efficiently within a relatively narrow range of revolutions per minute (RPM), while a train's operational requirements necessitate a wide range of speeds and tractive forces.

In diesel-electric locomotives, the diesel engine drives a generator, producing electricity. This electricity then powers electric traction motors, which are connected to the wheels. In this system, a tågväxellåda, in the traditional sense of mechanical gears, is not directly involved in transmitting power to the wheels. Instead, the control of power and speed is managed electronically by varying the output of the generator and the power supplied to the traction motors.

However, in diesel-hydraulic locomotives, a mechanical or hydraulic tågväxellåda is used. These transmissions employ complex gear sets or hydraulic torque converters to adjust the gear ratio between the engine and the wheels. This allows the engine to maintain an optimal RPM while providing the necessary torque for acceleration and speed. The selection of gears or hydraulic stages is often automated, responding to the locomotive's speed and the demands placed upon it. Modern tågväxellådor are designed for durability, efficiency, and smooth power delivery, playing a vital role in the performance and operational flexibility of diesel-powered railway vehicles.