The present disclosure relates to a hydraulic control circuit for crane slewing gear having directional valves arranged in work lines and controllable separately for the inflow and outflow to the hydraulic motor for the carrying out of a rotational movement of the slewing gear, wherein an inflow valve serves the control of the oil inflow from a hydraulic pump via the work line to the hydraulic motor and an outflow valve is provided via which the hydraulic motor can be relieved to the tank, wherein the work lines are each connected via at least one check valve to a common inlet of the outflow valve to relieve the hydraulic motor independently of the direction of rotation of the slewing gear via an outflow valve into the tank.

Shock absorber used for damping a control flow which is to be directed to the control valve belonging to a hydraulic system or is to be directed to the adjustable valve of the flow through which absorber the flow of the hydraulic fluid can be directed at least in one direction. The absorber is a stopper which restricts the run of the flow to be damped which stopper is equipped with one or several ducts which let the flow go through the mentioned stopper when the other orifice of the mentioned duct is blocked with a plate in such a way that bending of the mentioned plate opens access for the flow through the mentioned stopper due to the pressure of the flow coming along the mentioned duct.

A pressure compensated load sense hydraulic system and method is disclosed where a first pressure compensated valve controls flow between a pump and a first function based on a highest function load; and a second pressure compensated valve controls flow between the pump and a second function based on the highest function load. First and second operator controls activate the first and second functions, respectively. When the first function is stalled and the second function is activated, the controller closes the first valve to remove the first function load from the load sense circuit and prevent flow to or from the first function. The controller can determine the first function is stalled when a timer exceeds an initialization period. When the controller closes the first valve, it can cycle the first valve between a shutoff period where the valve is closed, and a refresh period where the valve is opened.

A pump discharge amount is divided in accordance with switch amounts of respective switch valves by leading load pressures of actuators to which compensator valves are connected to respective first pressure chambers of the compensator valves, leading a maximum load pressure selected by a selection unit to respective second pressure chambers of the compensator valves, and controlling respective openings of the compensator valves in accordance with respective pressure actions between the respective pressure chambers. A drain passage is provided to connect the first pressure chamber of the compensator valve to a tank, and a flow dividing ratio modification valve is provided to control a pressure in the first pressure chamber.

This disclosure describes techniques for a self-aligning system within a belt-driven linear actuator that enables a keyless or round profile piston to be sealed while maintaining an aligning and/or torque resisting ability. This enables the airspaces within the electromechanical actuator could be pressurized to perform a secondary load holding function that is redundant to the linear screw device.

A pressure-balance valve for balancing the pressures of fluids admitted into the pressure-balance valve via respective second ducts. The pressure-balance valve has both a chamber for guiding movement in translation of a piston, and also fluid flow paths, each comprising a said second duct and a first duct for admitting a fluid coming from the same fluid source as the fluid flowing in its second duct. Each of the first ducts is provided with a shutter co-operating with a ramp arranged on the piston. Movement of the piston in translation as a result of a pressure difference between the fluids respectively admitted into the second ducts causes one of the shutters to slide along the corresponding ramp and consequently allows additional fluid to be delivered from a first duct to the second duct of the same fluid flow path.

Shock absorber used for damping a control flow which is to be directed to the control valve belonging to a hydraulic system or is to be directed to the adjustable valve of the flow through which absorber the flow of the hydraulic fluid can be directed at least in one direction. The absorber is a stopper which restricts the run of the flow to be damped which stopper is equipped with one or several ducts which let the flow go through the mentioned stopper when the other orifice of the mentioned duct is blocked with a plate in such a way that bending of the mentioned plate opens access for the flow through the mentioned stopper due to the pressure of the flow coming along the mentioned duct.

A hydraulic system in a work machine includes a travel operation device provided in a pilot oil path between a hydraulic pump a travel pump and including an operation member and configured to generate a pilot pressure supplied via the pilot oil path and an additional pilot pressure in accordance with an operation amount of the operation member. The travel pump is to control a flow direction of hydraulic oil supplied to a travel motor based on the pilot pressure and the additional pilot pressure. A pressure selection valve is provided in a first coupling oil path to select a selected pressure from the pilot pressure and the additional pilot pressure to apply the selected pressure to the pilot hydraulic oil in the second coupling oil path. A pressure adjustment valve is provided in a second coupling oil path to control the selected pressure to be an adjusted pilot pressure.

A hydraulic system in a work machine includes a travel operation device to generate a pilot pressure and an additional pilot pressure in accordance with an operation amount of the operation member. A travel pump is to control a flow direction of hydraulic oil supplied to a travel motor based on the pilot pressure and the additional pilot pressure. A pressure selection valve is provided in a first coupling oil path to select a selected pressure from the pilot pressure and the additional pilot pressure to apply the selected pressure to the pilot hydraulic oil in a second coupling oil path. A pressure adjustment valve is provided in the second coupling oil path to control the selected pressure to be an adjusted pilot pressure. A differential pressure generation valve is provided in the second coupling oil path to generate differential pressure upstream or downstream relative to the pressure adjustment valve.

A system for controlling hydraulic fluid flow within a work vehicle includes a hydraulic load and a pump configured to supply hydraulic fluid to the hydraulic load via a fluid supply conduit. The system also includes a flow control valve fluidly coupled to the fluid supply conduit upstream of the hydraulic load, a pilot-operated compensator valve fluidly coupled to the fluid supply conduit upstream of the flow control valve, and a pilot conduit fluidly coupled to the pilot-operated compensator valve such that the pilot conduit is configured to supply a pilot flow of hydraulic fluid to the pilot-operated compensator valve. Additionally, the system include a pilot selector valve configured to selectively fluidly couple the pilot conduit to either a first pilot source conduit or a second pilot source conduit to adjust a source of the pilot flow supplied to the pilot-operated compensator valve.