| 摘要 |
An agricultural implement is provided with trailing swing arms, each of which has a trailing wheel. Each swing arm is provided with a lifting device in the form of a piston operating in a cylinder. This lifting device establishes the height at which the implement is supported relative to the ground. Each swing arm is also provided with a gas spring in the form of an upper piston operating in a cylinder to control the pressure of the implement against the ground surface despite undulations in the surface upon which the wheels engage. The lifting devices and the gas springs operate in conjunction with each other to establish substantially uniform pressure of the implement against the ground over the transverse width of the implement. A control device controls the pressures prevailing in the gas springs, which pressures may be different.
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