Patent ID: 7789201
Filing Date: 2010-09-07
Classification: E02D,E21B

Abstract:
1. A gear unit for foundation engineering devices, comprising: a gear housing having an internal pressure, a power-driven, active setting device for changing the internal pressure in the gear housing, the active setting device including a compensating tank partly filled with gear oil, a pressure change device for hydraulically generating a change in the pressure of the gear oil in the compensating tank, and a piston for changing the internal volume of the compensating tank, wherein the piston includes a piston rod, a measuring device for measuring the extension of the piston rod and determining the level of the gear oil based on the measured extension of the piston rod, a control device for controlling the pressure change device, fluid communication means providing fluid communication between the compensating tank and the gear housing for changing the internal pressure in the gear housing in response to the pressure change in the gear oil in the compensating tank, by supplying gear oil to the gear housing from the compensating tank and by discharging gear oil from the gear housing to the compensating tank, and damping means provided in the compensating tank for damping a pressure change in the gear oil in the compensating tank generated by the pressure change device and transmitting the dampened pressure change to the gear oil in the gear housing via the fluid communication means, wherein the damping means and the piston separate the gear oil and the pressure change device from each other.