An automatic swing device for a work machine is capable of performing a sieve operation in the posture where a work device is always at a posture suitable for sieve operation. An automatic swing device includes a posture sensor that detects a posture of a work device, and a controller that outputs signals to operate at least a stick cylinder and a bucket cylinder of the work device. The controller has an automatic swing mode in which the work device is automatically swung while the posture detected by the posture sensor is maintained to be in the range of a predetermined posture.

A vibrating ripper for demolition comprising a chassis, a vibrating assembly supported by the chassis so that it can move with an alternating translational motion along a work direction between a first stroke limit position and a second stroke limit position, and at least one demolition tool associated with the vibrating assembly.

In the second stroke limit position, the vibrating assembly is spaced further from the chassis with respect to the first stroke limit position.

The vibrating assembly comprises a main body associated with at least one pair of oppositely rotating eccentric masses actuated rotationally by at least one motor element.

The particularity of the invention resides in that it comprises means for detecting an abnormal movement of the vibrating assembly along the work direction beyond at least one of the stroke limit positions.

A work machine includes an unload lever swingably supported by an operation box, the unload lever being configured to be swung to select whether or not to supply an operation fluid to the hydraulic actuator. The unload lever includes a second guide pin to move in a first guide groove in accordance with the swinging of the unload lever, the second guide pin being positioned on a first end of the first guide groove when the unload lever is positioned to a pushed-down position and positioned on a second end of the first guide groove when the unload lever is positioned to a pulled-up position. The first guide groove includes a first latch portion to latch the second guide pin at the first end of the first guide groove, and a second latch portion to latch the second guide pin at the second end of the first guide groove.

A hydraulic system (600) and method for reducing boom dynamics of a boom (30), while providing counter-balance valve protection, includes a hydraulic cylinder (110), first and second counter-balance valves (300, 400), first and second control valves (700, 800), and first and second blocking valves (350, 450). A net load (90) is supported by a first chamber (116, 118) of the hydraulic cylinder, and a second chamber (118, 116) of the hydraulic cylinder may receive fluctuating hydraulic fluid flow from the second control valve to produce a vibratory response (950) that counters environmental vibrations (960) on the boom. The method may include measuring first pressure ripples at the second chamber and reducing a magnitude of second pressure ripples at the first chamber. The pressure ripples may be transformed into a flow command by multiplying the pressure ripples by a gain and/or phase shifting. The gain and/or the phase shifting may be adjusted by feedback. The feedback may include the second pressure ripples at the load holding chamber, a position of the hydraulic actuator, and/or an operator input. A reference signal may be filtered with a moving average filter.

The present invention relates to a hydraulic percussion device and a construction apparatus having the same, the hydraulic percussion device comprising: a cylinder; a piston; a backward port connecting a front chamber of the cylinder to a hydraulic source; a forward port formed on a rear chamber of the cylinder; a forward/backward valve for controlling the forward and backward movement of the piston; a control line for moving the forward/backward valve to a forward-movement location; a long-stroke port formed between the forward port and the backward port; a short-stroke port formed between the backward port on the cylinder and the long-stroke port; a shift valve disposed between the short-stroke port and the control line; a proximity sensor for detecting a bottom dead point of the piston upon the stroke on an object; and a controller for determining a striking condition on the basis of the detected bottom dead point, and transmitting a control signal to the shift valve.

A material handling machine can be operated in a bucket shake control mode to override proportional control of a valve controlling fluid flow to and from a bucket tilt cylinder of the machine. Fluid flow through the valve upon actuation of a tilt controller such a joystick therefore is proportional to actuator stroke when the shake control system is deactivated and is always maximized regardless of actuator stroke when the shake control system is activated. Bucket shake control is activated through the manual operation of a control device such as a joystick-mounted switch. As a result of this arrangement, proportional control valve actuation always occurs immediately upon bucket tilt controller movement in a direction that is dependent upon a direction of bucket tilt controller movement from the neutral position thereof.

An implement vibration system and method is disclosed that includes a vibration activation device; an electrohydraulic mechanism and a controller. The controller monitors the vibration activation device and sends movement signals to the electrohydraulic mechanism to control implement movement. When the vibration activation device is activated, the controller sends vibration signals to the electrohydraulic mechanism to cause the implement to vibrate. An operator control can send implement commands where the movement signals are based on the implement commands, and when vibration is activated the controller can superimpose the vibration signals on the movement signals. The vibration signals can cause a hydraulic cylinder to repeatedly extend and retract. An electrohydraulic control valve can receive the movement signals and control hydraulic flow to the hydraulic cylinder based on the movement signals. The vibration signals can be complementary signals. The amplitude and/or frequency of the vibration signals can be adjustable.

A working machine including a ground engaging structure and a propulsion system for moving the working machine via the ground engaging structure. A body is supported on the ground engaging structure, and a working arm is connected to the body and has a carriage at one end for receiving an attachment. A control system is provided for selectively and variably oscillating the carriage.

A hydraulic system includes a pressure-driven actuator operable to provide a mechanical output in response to a pressure input, a single hydraulic circuit communicating with the pressure-driven actuator, a vibratory actuator in the single hydraulic circuit and operable to generate a first component of the mechanical output at a first frequency, and a hydraulic supply apparatus separate from the vibratory actuator, in the single hydraulic circuit, and operable to generate a second component of the mechanical output at a second frequency less than the first frequency.

The invention relates to a device for generating oscillations for a construction machine, comprising a housing, a piston which is movable back and forth in a working chamber in the housing between a first return point and a second return point, a pressurized fluid supply through which in each case pressurized fluid can be fed into and discharged from the working chamber via at least one actuatable control valve in the region of the first return point and the second return point, wherein the piston can be induced into a reciprocating motion in order to generate the oscillations, and a control unit which is configured to actuate the at least one control valve and by means of which the movement of the piston in the working chamber is controllable and variable. According to the invention, it is provided that the control unit is configured to control the piston in a first operating mode for generating oscillations and in a second operating mode for generating impact pulses, wherein a strike surface is formed on at least one end side of the working chamber, onto which surface the piston strikes when it reaches at least one return point in order to generate an impact pulse.