The present invention provides a leveling control system for a forestry machineemploying position sensors that relay information about the orientation ofthe carriage in relation to the swing-house assembly in order to control rolland pitch in a manner that maximizes the operating envelope of the leveling mechanism.The angles of pitch and roll of the swing-house assembly in relation to the carriageare measured and/or calculated and a controller limits operation of the levelingmechanism to an operating envelope that may be described in terms of pitch androll. The cylinders are decelerated gradually as the operating envelope is approached.The controller can include an automatic leveling mode. The controller can changethe function of the fore, aft, left and right operator controls so that they aretrue from the operators frame of reference regardless of the rotary positionof the cab relative to the carriage.
