A hydraulic system of a construction machine includes: control valves interposed between a main pump and hydraulic actuators; and first solenoid proportional valves connected to pilot ports of the control valves. The hydraulic system further includes: an unloading valve including a pilot port; and a second solenoid proportional valve connected to the pilot port of the unloading valve by a secondary pressure line and connected to an auxiliary pump by a primary pressure line. A switching valve including a pilot port connected to the secondary pressure line by a pilot line is interposed between the auxiliary pump and the first solenoid proportional valves.

A hydraulic circuit for an adaptive park braking system and method of operation thereof. The method of operating an adaptive park braking system includes providing a vehicle having a motor, a front axle system, a rear axle system, wherein the front axle system has one or more front axle braking systems and the rear axle system has one or more rear axle braking systems. Identifying when the vehicle is engaged in a digging operation. Disconnecting the front axle system or the rear axle system from driving engagement with the motor of the vehicle. Activating the one or more braking systems of the disconnect axle system to apply an amount of force to the disconnected axle system of the vehicle. Then applying an amount of torque with the motor to the axle system in driving engagement with the motor.

A hydraulic system of a construction machine includes: control valves interposed between a main pump and hydraulic actuators; and first solenoid proportional valves connected to pilot ports of the control valves. The hydraulic system further includes: an unloading valve including a pilot port; and a second solenoid proportional valve connected to the pilot port of the unloading valve by a secondary pressure line and connected to an auxiliary pump by a primary pressure line. A switching valve including a pilot port connected to the secondary pressure line by a pilot line is interposed between the auxiliary pump and the first solenoid proportional valves.

A safety protection system (100) for engineering machinery, relating to the technical field of engineering machinery. Said system comprises: multiple groups of sensors (101), a controller (102), a control valve (103), a hydraulic safety valve (104), and an operating mechanism (105); the control valve (103), the hydraulic safety valve (104), and the operating mechanism (105) are sequentially connected by means of fluid paths; the controller (102) is electrically connected to a pilot electromagnetic valve (106) in the hydraulic safety valve (104), to detect whether the pilot electromagnetic valve (106) is power on; the multiple groups of sensors (101) are respectively provided at different positions in an operating chamber of engineering machinery; the controller (102) is electrically connected to the multiple groups of sensors (101), to acquire multiple groups of operating data from the multiple groups of sensors (101) when detecting that the pilot electromagnetic valve (106) is power on; and the controller (102) is further electrically connected to the control valve (103) to determine, according to the multiple groups of operating data, whether a safe operation condition is met, and if not, to shut off the control valve (103), so as to prevent hydraulic fluid from being supplied to the operating mechanism (105). The safety protection system (100) for engineering machinery can detect the operating state of a driver, achieving safety protection for engineering machinery in a working state, and improving the safety of engineering machinery. The present invention also relates to a safety protection method for engineering machinery.

A collision avoidance system for a work machine includes at least one sensor configured to generate a signal indicative of a presence of at least one obstacle in a surrounding area of the work machine, at least one imaging device, a display device, and a controller. The controller receives the signal indicative of the presence of the obstacle and determines a position of the obstacle relative to the work machine based on the signal received from the sensor. The controller generates a first control signal to prevent a movement of the work machine, halt the movement of the work machine, or reduce a velocity of the work machine based on the determination of the position of the obstacle. The controller generates a second control signal for displaying an updated display view that provides a visual indication of the presence of the obstacle in the surrounding area of the work machine.

An engine (12) drives a variable capacity-type hydraulic pump (16), discharged hydraulic oil is selectively supplied to a cooling fan (19) and a hoist cylinder (11) in accordance with switching of a selection valve (17), thereby controlling the same on the basis of each target value. A pump discharge pressure (Pp) of the hydraulic oil discharged from the hydraulic pump (16) and a motor supply pressure (Pm) of the hydraulic oil supplied to a hydraulic motor (18) via the selection valve (17) are detected by sensors (27, 28) and are compared with pressure determination values stored in advance as a pump discharge pressure (Pp) and an actuator supply pressure (Pm) generated when the target value is achieved. Presence/absence of abnormality in the hydraulic actuator control device (15) is determined on the basis of a result of the comparison, and when abnormality is determined to have occurred, control is performed to minimize the capacity of the hydraulic pump (16).

A working vehicle provided with a fixed-capacity hydraulic pump driven by power from an engine and a working hydraulic actuator driven by working oil pumped from the fixed-capacity hydraulic pump is a rotary working vehicle which is provided with an electromagnetic relief valve for modifying the pressure of working oil from the fixed-capacity hydraulic pump, and the rotary working vehicle is such that if the actual number of revolutions (N) of the engine is reduced by a set number of revolutions (Ns) as the load on the engine increases, then the electromagnetic relief valve operates in accordance with the deviation (e) between the actual number of revolutions (N) of the engine and the specified number of revolutions (Ns), and the pressure of the working oil from the fixed-capacity hydraulic pump is modified.

The invention includes digging equipment having a self-propelled base machine provided with an arm that supports a digging tool. The digging tool is provided with a device for crumbling soil. The digging tool is operatively connected to the base machine through a suspending flexible element that can be wound or unwound by a winch arranged on the base machine. The base machine also includes a main power engine, to actuate all the hydraulic apparatuses of the digging equipment, and a hydraulic system consisting of two independent and separate hydraulic circuits (S; U). A first hydraulic circuit (S) is configured to control and supply the main service apparatuses of the base machine, including a movement apparatus for moving the digging tool. A second hydraulic circuit (U) is configured to control and supply the main digging apparatuses of the digging tool, including at least the actuators of the device for crumbling soil.

A control method for a fan of a work vehicle includes supplying, when an engine is started, a first current to a solenoid of a variable relief valve such that the hydraulic fluid flows by a first flow rate, supplying, when a rotational speed of the engine becomes larger than a first rotational speed threshold value, a second current larger than the first current to the solenoid such that the hydraulic fluid flows by a second flow rate smaller than the first flow rate to reduce the rotational speed of the fan, and supplying, when the rotational speed of the engine becomes larger than a second rotational speed threshold value that is larger than the first rotational speed threshold value, a current to the solenoid to change the rotational speed of the fan, the current corresponding to a temperature of liquid flowing in the work vehicle.

Systems and methods to activate one or more indicators, positioned on heavy hydraulic-based equipment to provide indication that the heavy hydraulic-based equipment is in an operation are described herein. The system may include a hydraulic initiation lever positioned proximate an operator's seat of the equipment and configured to be actuatable to an inactive position and an active position, the hydraulic initiation lever when in the active position configured to generate an unlock signal to thereby enable hydraulic operation of the heavy hydraulic-based equipment. The system may include one or more indicators configured to receive the unlock signal, the one or more indicators configured to activate in response to reception of the unlock signal and to deactivate in response to no reception of the unlock signal.