Torque converter, automatic transmission of forklift
Purpose
The torque converter of a forklift automatic transmission is an important transmission unit and serves for:
* Transfer torque from engine to gearbox
* Torque multiplications at low engine speeds
* Smooth starting and gear shifting
* Transmission overload protection
Design
The torque converter consists of three main elements:
* Pump impeller (driven by engine)
* Reactor wheel (connected to the automatic transmission shaft)
* Turbine impeller (connected to reactor wheel)
All these elements are enclosed in a common sealed housing filled with working fluid (hydraulic oil).
Operating principle
The torque converter operates on the principle of hydrodynamic torque transmission:
* The pump impeller creates a fluid flow that is directed to the turbine impeller.
* The turbine impeller converts the kinetic energy of the fluid flow into mechanical rotational energy and transfers it to the reactor wheel.
* The reactor wheel changes the direction of fluid flow and returns it to the pump impeller.
This closed circulation loop ensures transmission and torque multiplication.
Transformation ratio
The transformation coefficient of the torque converter is determined by the ratio of the speeds of the pump and turbine impellers. At low engine speeds, the transformation ratio is high, providing high tractive effort at low speed. As engine speed increases, the transformation ratio decreases, approaching 1:1 at high speeds.
Operating modes
The torque converter can operate in various modes:
*Hydraulic coupling mode (at low engine speed): the transformation ratio is high and the torque is transmitted with increasing force.
* Slip mode (at medium engine speed): the transformation ratio is reduced and torque is transmitted with slip.
* Mechanical link mode (at high engine speed): the transformation ratio approaches 1:1, and torque is transmitted without slipping.
Advantages of torque converters in automatic transmissions of forklifts
* Smooth starting and gear shifting
* High tractive effort at low engine speeds
* Transmission overload protection
* Increased gearbox life
* Reduce vibration and noise