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 hydraulic pump control apparatus for construction equipment includes a first hydraulic pump; a first hydraulic actuator driven by the hydraulic oil of the first hydraulic pump; a first control valve installed on the fluid channel of the first hydraulic pump; a second hydraulic pump connected, to a power take-off apparatus of an engine; a second hydraulic actuator driven by the hydraulic oil of the second hydraulic pump; a second control valve installed on the fluid channel of the second hydraulic pump; a pressure sensor that detects the pressure of the second hydraulic pump; a regulator that controls the amount of oil discharged from the first hydraulic pump; and a controller that computes a horse power value using the detected pressure value of the second hydraulic pump and the amount of oil discharged from the second hydraulic pump and inputs a control signal to the regulator to discharge an amount of oil that corresponds to the difference between the maximum working horse power value of the engine and the computed horse power value of the second hydraulic pump.

An object of the invention is to achieve a travel speed known in the art during travelling operation, improve energy efficiency by reducing energy loss, and obtain favorable travel operability less susceptible to effects from variations in a travel load and changes in a pump delivery pressure when travelling operation is performed through operation of a travel lever over a half stroke range or less. A variable restrictor valve 80 is disposed in parallel with a flow sensing valve 50 of an engine speed sensing valve unit 13. A travel pilot pressure is adapted to act in an opening direction of the variable restrictor valve 80. The variable restrictor valve 80 is set to have a continuously increasing opening area from a full closure to a maximum with an increasing travel pilot pressure. Travel flow control valves 6d and 6e have an opening area that allows a predetermined flow rate QT required for traveling to be obtained even when a target LS differential pressure is decreased to a second specified value Pa3 when the travel lever is fully operated. In a first half of a spool stroke, the travel flow control valves 6d and 6e have an opening area approximate to an opening area of comparative example 1.

Control valves 100f, 100g, and 100h that reduce flow passage areas of parallel hydraulic fluid lines 41f, 41g, and 41h respectively when operating devices 34a, 34b for traveling are operated, are each disposed in the parallel hydraulic fluid line 41f, 41g, or 41h so that if saturation occurs during combined operations control likely to generate a significant difference in load pressure between any two actuators, the control valve prevents full closing of a pressure compensating valve lower in load pressure and thus prevents a slowdown and stop of the actuator undergoing the lower load pressure, and so that if saturation occurs during combined operations control likely to generate a particularly significant difference in load pressure between any two actuators, the control valve ensures a necessary supply of hydraulic fluid to the actuator higher in load pressure, thereby preventing a slowdown and stop of the actuator higher in load pressure.

Power machines, control systems and methods that adjust engine speed based upon actuation of user input controls that control other power machine functions such as travel functions and lift arm functions. By controlling engine speed at least partially in response to the user input devices controlling other machine functions, more optimal engine speeds can be achieved.

A load sense open center hydraulic system provides efficiency and operator feedback and includes one or more constant flow-open center valves (218); respective one or more parallel power cores (238) operatively coupled to the one or more constant flow-open center valves; a variable capacity pump (246) directly fluidly connected to the one or more parallel power cores; and a pressure compensated flow control fluidly connected between the variable capacity pump and the one or more constant flow-open center valves. The one or more constant flow-open center valves are not fluidly coupled to a fixed capacity pump.

Provided is a hydraulic drive system for a work machine configured with a single solenoid proportional valve for a regeneration circuit, wherein substantially the same actuator speed can be secured irrespective of whether or not hydraulic fluid discharged from a hydraulic actuator is regenerated for driving of another hydraulic actuator. The hydraulic drive system includes: a regeneration line that connects a bottom-side hydraulic chamber of a hydraulic cylinder 4 to a portion between a hydraulic pump device 50 and a second hydraulic actuator 8, and a regeneration flow rate adjustment device that supplies, at an adjusted flow rate, at least part of the discharged hydraulic fluid to a portion between the hydraulic pump device 50 and the second hydraulic actuator; a discharge flow rate adjustment device that discharges, at an adjusted flow rate, the discharged hydraulic fluid to a tank; one electric drive device 22 that simultaneously controls the regeneration flow rate adjustment device and the discharge flow rate adjustment device; and a control unit 27 that outputs a control command to the electric drive device in such a manner that falling speed of a first driven body does not vary significantly, irrespective of the magnitude of the regeneration flow rate caused by the regeneration flow rate adjustment device.

A hydrostatic drive includes a diesel engine and a hydrostatic adjustable machine which supplies multiple consumers in normal operation as a pump. The machine has a pressure/flow regulator to which is communicated, according to the load-sensing principle, the highest load pressure of the consumers, in particular when the machine is operated as a pump. In order to realize a start/stop function of the diesel engine, a previously charged high-pressure reservoir supplies the hydrostatic machine, which then acts as a starter motor for the diesel engine. In order to switch from pump to starter motor, the hydro-machine is adjusted over zero. In order for this switch to take place quickly and reliably, the pressure/flow regulator is deactivated by means of a switching valve and the adjustment device is supplied with an adjustment pressure medium via the switching valve, which medium is taken from the high-pressure reservoir or from an auxiliary reservoir.

An oil-pressure driving system includes a variable displacement oil-pressure pump, tilting angle adjuster, electric motor, and control device. In the control device, a target assist torque calculating portion calculates a target assist torque, a first torque limiting portion limits the target assist torque to an output value that is a virtual limit value or less, and a drive control portion controls the electric motor such that the electric motor outputs a command torque corresponding to the output value. Further, in the control device, a torque deficiency calculating portion calculates a torque deficiency by subtracting the output value from the target assist torque, a tilting angle calculating portion calculates a tilting angle command value by which the output torque of the oil-pressure pump is reduced by the torque deficiency, and a tilting angle control portion outputs a tilt signal corresponding to the tilting angle command value to the tilting angle adjuster.

A hydraulic system is adapted to provide at least one of a fluid flow at a variable fluid pressure or a fluid flow at a variable fluid displacement. A pressure sensor measures a fluid pressure. A controller is in communication with the engine and the pressure sensor. Wherein, the controller sends an engine speed signal to operate the engine in an open state and controls the fluid displacement or the fluid pressure of the hydraulic system to a first load condition. Further wherein, the controller detects an engine speed and a fluid pressure of the hydraulic system with the pressure sensor when the engine is in the open state and the hydraulic system is in the first load condition. Further wherein, the controller operably calculates a total engine torque as a function of the detected engine speed and fluid pressure when the hydraulic system is in the first load condition.