Hydraulic system having variable back pressure control

A hydraulic system for a work machine having a linkage system, comprising:

• a tank configured to hold a supply of fluid;
• at least one hydraulic actuator associated with the linkage system to affect movement of the linkage system, the at least one hydraulic actuator having at least one pressure chamber;
• an independent metering valve associated with the at least one pressure chamber and having a valve element movable between a first position at which fluid communication between the at least one pressure chamber and the tank is blocked, and a second position at which fluid is allowed to drain from the at least one pressure chamber to the tank;
• a sensor configured to sense at least one operating parameter of the linkage system and to generate a signal indicative of the at least one operating parameter;
• and
• a controller in communication with the independent metering valve and the sensor, the controller configured to move the valve element of the independent metering valve in response to the signal.

A method of operating a hydraulic system associated with a linkage system, the method comprising:

• moving an independent metering valve element between a first position and a second position to selectively block fluid from or drain fluid from a first chamber of a hydraulic actuator to a tank;
• sensing a parameter indicative of a pressure within a second pressure chamber of the hydraulic actuator;
• and
• moving the independent metering valve element between the first and second positions in response to the pressure.

A method of operating a hydraulic system associated with a linkage system, the method comprising:

• moving an independent metering valve element between a first position and a second position to selectively block fluid from or drain fluid from at least one chamber of a hydraulic actuator to a tank;
• sensing at least one operating parameter of the linkage system;
• generating a signal indicative of the at least one operating parameter;
• and
• moving the independent metering valve element between the first and second positions in response to the signal.

A work machine comprising:

• a work tool;
• a linkage system operably connected to the work tool;
• and
• a hydraulic system configured to affect movement of the linkage system, the hydraulic system including:
• a tank configured to hold a supply of fluid;
• at least one hydraulic actuator associated with the linkage system to affect movement of the linkage system, the at least one hydraulic actuator having a first pressure chamber and a second pressure chamber;
• an independent metering valve associated with the first pressure chamber and having a valve element movable between a first position at which fluid communication between the first pressure chamber and the tank is blocked, and a second position at which fluid is allowed to drain from the first pressure chamber to the tank;
• at least one sensor configured to sense a parameter indicative of a pressure in the second pressure chamber;
• and
• a controller in communication with the independent metering valve and the sensor, the controller configured to move the valve element of the independent metering valve in response to the pressure.

A work machine comprising:

• a work tool;
• a linkage system operably connected to the work tool;
• and
• a hydraulic system configured to affect movement of the linkage system, the hydraulic system including:
• a tank configured to hold a supply of fluid;
• at least one hydraulic actuator associated with the linkage system to affect movement of the linkage system, the at least one hydraulic actuator having at least one pressure chamber;
• an independent metering valve associated with the at least one pressure chamber and having a valve element movable between a first position at which fluid communication between the at least one pressure chamber and the tank is blocked, and a second position at which fluid is allowed to drain from the at least one pressure chamber to the tank;
• a sensor configured to sense at least one operating parameter of the linkage system and to generate a signal indicative of the at least one operating parameter;
• and
• a controller in communication with the independent metering valve and the sensor, the controller configured to move the valve element of the independent metering valve in response to the signal.