Patent ID: 7090475

Claim:
Hydraulic control circuit for a hydraulic motor having at least two speeds, with which switching from one speed to another takes place by changing an absorption volume, comprising: a valve arrangement configured to selectively neutralize absorption volumes of selected motor working chambers, wherein a related intake side for the selected motor working chambers is short-circuited with an outlet side, wherein the valve arrangement has at least one intermediate switching position between two switching positions assigned to the switching process, in each instance, in which the intake side is connected with the outlet side, with throttling of flow medium supply to the motor working chambers to be neutralized, by an orifice arrangement, wherein control of the valve arrangement takes place such that a valve body of the valve arrangement is configured to move through the intermediate switching position in a controlled manner, wherein the valve arrangement includes a first directional valve formed by an infinitely adjustable 4/2-way valve, which produces a connection between an intake of a motor working chamber with an absorption volume not to be neutralized and the intake of the motor working chamber with an absorption volume to be neutralized and between outlets of the motor working chambers, in each instance, in a one end switching position of the 4/2-way valve, and in another end switching position of the 4/2-way valve short-circuits the intake and outlet of the motor working chamber to be turned on and shut off and, at a same time, blocks a remainder of the connection, wherein a control pressure of a control pressure line downstream from an orifice is used to control the valve arrangement, wherein the orifice lies downstream from an inlet directional valve, with which the control pressure line can be connected either with a tank pressure or with an amplifier pressure, and wherein the orifice is configured to be circumvented by a sequential switching valve that switches to circumvent the orifice above a threshold value for the control pressure for the valve arrangement.