Hydraulic-mechanical automatic transmission for agricultural vehicles | Faculty of Mechanical Engineering and Ship Technology at the Gdańsk University of Technology

Scientists from the Faculty of Mechanical Engineering and Ship Technology of Gdańsk University of Technology have designed a hydraulic-mechanical automatic transmission for agricultural vehicles and working machines. It will allow for a smooth change of gear at low speed and a step change of gear in the range of high speeds.

The gearbox was designed under the Lider VIII program. The project was financed by the National Center for Research and Development. The co-financing amount was PLN 1 197 500.

– At low travel speeds, the drive is transferred via a hydraulic transmission consisting of a prototype variable displacement piston pump and a prototype two-speed piston hydraulic motor with free wheel function. On the other hand, at higher speeds, the drive is transmitted through a two-speed gear transmission, equipped with a set of three wet clutches, ensuring smooth shifting. There is no need to disconnect the drive from the vehicle wheels - said Piotr Patrosz, PhD, Eng. from the Institute of Mechanics and Machine Design, the manager of the project.

The use of a hydraulic transmission at low speeds allows for very high torques and smooth control of the drive parameters in difficult terrain conditions. Thanks to the mechanical transmission used at higher speeds, the drive becomes more efficient, which minimizes fuel consumption.

Clutch control unit

The gearbox is equipped with an electro-hydraulic control unit for wet clutches and the volume of the pump and the hydraulic motor.

– As part of the project, we also designed an axial piston pump with an offset axis of rotation of the swivel disc, which increased its volumetric efficiency. On the other hand, the prototype piston motor with a tilting plate allows work in a free wheel. As a result, it did not have to be mechanically disconnected from the transmission when not in use.

The gearbox can be introduced into production and used in real vehicles. This particular prototype was designed with the existing telehandler in mind, yet the application can be much wider. In theory, it can be applied to any slow running machine.

Members of the project team: Piotr Patrosz, PhD, Eng., Paweł Załuski, PhD, Eng., Marcin Bąk, MSc. and Sławomir Sommer, MSc

In the photo from the left: Piotr Patrosz, PhD, Eng., Paweł Załuski, PhD, Eng., Marcin Bąk, MSc. Photo FMEST materials