Hydrotransmatic Plus Driveline System

Posted on August 29, 2011

Hytrac has partnered with Stiebel on the development of the Hydrotransmatic Plus transmission for heavy off-highway vehicles with operating weights of more than 24,250 lb. such as wheel loaders, motor graders, mining machines and forestry equipment. Stiebel manufactured the pump drives for the transmission and Hytrac provided drivetrain technology for the Hydrotransmatic Plus, which was engineered to reduce fuel consumption, increase available and provide uninterruptable traction.

The driveline system uses a planetary gearbox, driven by two standard bent axis hydraulic motors. Three clutches are operated so that the hydraulic motors are always providing optimized vehicle traction force and speed at the best efficiency, the companies said. In the first gear operation mode both hydraulic motors are coupled to the sun wheel of the planetary gear. Torque is added to provide high force at the vehicle wheel. Gear ratio is rated 4.73 to 6.51

In the second gear operation mode, one of the hydraulic motors is taken off the sun wheel and coupled to the ring wheel of the planetary gearbox. Here, the addition of the revolution of both hydraulic motors takes into account the need of higher vehicle speed for a gear ratio of 1.26 to 1.74.

Within the third gear operation mode the planetary gear is blocked between the ring wheel and the sun wheel. This functions as a shaft, resulting in higher mechanical efficiencies and optimal lower engine speeds, the company said. Also, the hydraulic motors are then driven with the lowest possible revolutions. For this reason, the third gear operation mode is named the ECO-Drive (Economical drive).