A system for enabling an upper swing body of construction equipment to swing freely. A working device is attached to the upper swing body to lift and move an object. A swing motor is connected to a power unit to swing the upper swing body. A controller is electrically connected to the working device and the swing motor to detect forces applied to the working device, and based on the detected forces, generating a control signal to control the swing motor so that the upper swing body swings freely. The system enables the upper swing body to swing freely to reduce energy consumption while ensuring safety when the upper swing body lifts a load.

Provided is a swing-back preventing apparatus capable of preventing a hydraulic actuator in a stop state from operating by undesired load. The swing-back preventing apparatus includes a housing, a piston, and a pair of biasing members. First and second spaces are formed between the piston and the housing, and the piston includes a pair of communication passages that are communicable with first and second spaces. When the piston is located at a first offset position, the first space is blocked from a first port. When the piston separates from the first offset position, the first space is connected to the first port. When the piston is located at a second offset position, the second space is blocked from a second port. When the piston separates from the second offset position, the second space is connected to the second port. When the piston is located at a position on the first offset position side of a neutral position, a first communication passage is connected to the first space. When the piston is located in a range from the neutral position to the second offset position, the first communication passage is blocked from the first space. When the piston is located at a position on the second offset position side of the neutral position, a second communication passage is connected to the second space. When the piston is located in a range from the neutral position to the first offset position, the second communication passage is blocked from the second space.

A working machine includes a lower body, a turning body, a turning manipulating member which turns the turning body, a hydraulic motor which rotationally drives the turning body, a brake device which brakes the hydraulic motor, a main hydraulic source which supplies hydraulic oil to the hydraulic motor, and a direction control valve which controls a flow direction of the hydraulic oil according to the manipulated variable of the turning manipulating member, in which in a state where the hydraulic motor is braked by the brake device based on a manipulation of a brake manipulating member, when the turning manipulation is performed by the turning manipulating member, a brake applied to the hydraulic motor by the brake device is released with respect to turning in an indication direction indicated by the turning manipulation such that the turning body turns in the indication direction.

A system for operating a circle drive gear of a machine includes a pump configured to output pressurized fluid, an implement control valve fluidly coupled to the pump, a bi-directional hydraulic motor located downstream of the implement control valve and fluidly coupled to the implement control valve via a first delivery line and a second delivery line. The hydraulic motor has an output shaft that is configured to be rotatively driven by pressurized fluid output by the pump. A brake is disposed on the output shaft of the hydraulic motor and engages with the output shaft with the help of a spring force for reducing a rotational speed of the output shaft in a brake engage state. The brake operatively disengages from the output shaft in a brake release state with the help of fluid pressure in at least one of the first delivery line and the second delivery line.

A working machine includes a branched tube connected to a branched portion branching from an operation fluid tube, a plurality of input tubes connected to the second actuator valves, a plurality of output tubes connected to a pressure receiver portion of the second hydraulic device, a main tube connected to the third actuator valve, and a relay device, and the relay device includes a plurality of input ports connected to the plurality of input tubes, a plurality of output ports connected to the plurality of output tubes, a plurality of first flow lines connecting between the plurality of input ports and the plurality of input ports, a main port connected to the main tube, a branched port connected to the branched tube, and a second flow line arranged between the plurality of first fluid lines to connect between the main port and the branched port.

A method of controlling hydraulic fluid flow to an implement of a material handling vehicle includes coupling a boom arm to a vehicle frame for rotation about the vehicle frame, rotating a boom arm with respect to the vehicle frame with an actuator, coupling an attachment to the boom arm for rotation with respect to the boom arm, sensing a pressure of fluid in the actuator, communicating the sensed pressure to a control system, determining a baseline pressure of the attachment based upon the sensed pressure of the fluid in the actuator, and limiting fluid flow to the actuator with a control valve in response to the sensed pressure of the fluid in the actuator being above the baseline pressure.

Systems and methods are provided for a hydraulic stabilizer trim actuator (HSTA). The HSTA may operate one or more movable control surfaces. The HSTA operate responsive to commands issued by the pilot and/or by a controller and may include hydraulic architecture that minimizes the probability of an un-commanded movement or movement in the opposite direction of such commands

A directional control system of a marine vessel includes a steering control member manually operated by a user and operationally connected to a direction-variation member acting on or in the water, such as at least one rudder blade or at least one outboard engine, the direction-variation member having an angular position that is controlled by the steering control member; and a locking system locking the free variation of the angular position of the direction-variation member, which can be activated and deactivated to allow the variation of angular position and carry out a directional change, the locking system including a hydraulic cylinder having a piston dividing the cylinder into two chambers, which are connected by a bypass circuit that can be opened and closed by a switching member.

A hydraulic gage system is provided that includes a cylinder structure that is configured to allow the movement of a piston structure. The cylinder structure includes a plurality of vent structures that allows for the releasing of hydraulic fluid. A cover is positioned on the cylinder structure so when the piston passes the vent structures it relieves pressure as well as diminishes the force of impact on the cover by the piston.

The hydraulic system can include a control member that is operatively coupled to a member. The control member can include a hydraulic control member and an integrated inerter. Hydraulic fluid at variable pressures is moved through the hydraulic system by pumps. The hydraulic system can be configured for hydraulic fluid returning from the control member to the first pump to be delivered to the second pump prior to reaching the first pump. A dual-spool valve is positioned between the pumps and the control member to control the flow of the hydraulic fluid. The dual-spool valve is movable to move the hydraulic fluid at variable pressures into and out of first and second chambers of the control member. The dual spool valve can also be configured to operate the control member when a spool is not operational.