Abstract:
Embodiments relate to braking high-speed rotational cutting equipment. In particular, some embodiments relate to forestry machinery having a cutting or mower apparatus, and further having a hydraulic brake. The brake includes a counterbalance valve which pressurizes fluid at the motor outlet to a predetermined level when flow of hydraulic fluid from a pump to a motor is discontinued. The hydraulic brake may include a restrictor orifice to reduce sudden pressure increases on the motor. The predetermined pressure level may be between about 2000 psi and about 4000 psi and the orifice may have a diameter of between about 0.025 and 0.040 inches. The counterbalance vent port can hydraulically connect to the motor case line. An anti-cavitation valve can be at the counterbalance valve port can supply fluid to the motor inlet after the flow from the pump discontinues. Additional embodiments include related hydraulic control systems and methods.
Abstract:
Offenbart ist eine hydraulische - Steueranordnung zur Druckmittelversorgung eines hydraulischen Verbrauchers, beispielsweise des Drehwerks einer mobilen Arbeitsmaschine. Bei geringen Druckmittelvolumenströmen wird der vom Verbraucher ablaufende Druckmittelvolumenstrom mittels eines als Druckbegrenzungsventil ausgeführten Ablaufstauventils angestaut und entsprechend angedrosselt, so dass ein Gegendruck erzeugt wird, der ein Voreilen der vom hydraulischen Verbraucher betätigten Masse verhindern kann.
Abstract:
Einrichtung zur Kompensation der in Längsrichtung auf eine verfahrbare Kolbenstange eines lageveränderbaren Druckmittelzylinders (10) einwirkenden Gewichtskraft mittels einer elektronischen Steuereinheit (17) zur die Gewichtskraft berücksichtigenden Ansteuerung mindestens eines den Druckmittelzylinder (10) zumindest einseitig beaufschlagenden Mehrwegeventils (11), wobei ein Sensor (12) zur Erfassung der aktuellen Position des Druckmittelzylinders (10) vorgesehen ist, woraus die elektronische Steuereinheit (17) die aktuell in Längsrichtung auf die verfahrbare Kolbenstange einwirkende Gewichtskraft bestimmt, um hiervon abhängig den die Gewichtskraft kompensierenden Sollwert zur Ansteuerung eines als Druckregelventil ausgebildeten Mehrwegeventils (11) zu ermitteln.
Abstract:
A hydraulic control device of a working machine which controls the flow rate and flow direction of the pressure oil discharged from a hydraulic pump (20) through a control valve (27) before the oil is fed to a swing motor (4), characterized by comprising a bleed-off oil path (33) for bleeding off a part of the pressure oil fed to the swing motor (4), a cut valve (36) which is installed in the bleed-off oil path (33) and regulates the bleed-off amount, a controller (42) which controls the cut valve (36) through an electromagnetic proportional valve (37), and pressure sensors (40 and 41) which detect the control input of a swing remote-control valve (39), wherein the controller (42) sets the bleed-off amount according to the control input detected by the pressure sensors (40 and 41) and, based on the set bleed-off amount, controls the opening area of the cut valve (36) so as to suppress a shock caused at the time of abrupt swing operation.
Abstract:
Embodiments relate to braking high-speed rotational cutting equipment. In particular, some embodiments relate to forestry machinery having a cutting or mower apparatus, and further having a hydraulic brake. The brake includes a counterbalance valve which pressurizes fluid at the motor outlet to a predetermined level when flow of hydraulic fluid from a pump to a motor is discontinued. The hydraulic brake may include a restrictor orifice to reduce sudden pressure increases on the motor. The predetermined pressure level may be between about 2000 psi and about 4000 psi and the orifice may have a diameter of between about 0.025 and 0.040 inches. The counterbalance vent port can hydraulically connect to the motor case line. An anti-cavitation valve can be at the counterbalance valve port can supply fluid to the motor inlet after the flow from the pump discontinues. Additional embodiments include related hydraulic control systems and methods.
Abstract:
A working machine (1 ) and a method for operating a working machine (1 ) comprising a power source (120) and a plurality of driving wheels (130); a working hydraulic system (140) comprising at least one hydraulic pump (142, 144, 146) powered by the power source (120) for moving an implement (3) on the working machine (1 ) and/or for steering the working machine (1 ); a transmission line (110) arranged between the power source (120) and the driving wheels (130) for transmitting torque from the power source (120) to the driving wheels (130). The method is characterized by the steps of: detecting at least one operational parameter indicative of a load exerted on the working hydraulic system (140), determining if torque needs to be added, in addition to a torque delivered by the power source (120), on the basis of a magnitude of the detected operational parameter in order to reduce the a load on the power source (120), and adding torque in case additional torque is determined to be needed.
Abstract:
A pressurized hydraulic fluid system includes a charge pump (16), a hydraulic motor (24) drivingly coupled to the charge pump, and a main hydraulic unit (12) adapted to function as a pump to drive the hydraulic motor. The charge pump (16) is in fluid communication with the main hydraulic unit (12) for maintaining a sufficient inlet pressure in the main hydraulic unit (12) when it functions as the pump. The system further includes a hydraulic fluid reservoir (20) in fluid communication with an inlet of the charge pump, a hydraulic accumulator (22) in fluid communication with the main hydraulic unit, and a return flow passage (11) fluidly connecting the main hydraulic unit with the hydraulic fluid reservoir (20) for returning an excess flow of the hydraulic fluid generated by the charge pump (16) to the hydraulic fluid reservoir (20).
Abstract:
A hydraulically operated fan for a cooling system in an automotive vehicle. Two hydraulic motors drive a common fan shaft. A control system provides means to bypass flow in parallel with both motors or direct flow to both or one of the motors dependent on inlet flow and cooling signal conditions.
Abstract:
An exhaust manifold (25) of a fluid power and control system, the pressure of which is varied when the fluid motor (10) is subjected to a bidirectional positive or negative type load (W). This exhaust manifold (25) is also supplied from a source of exhaust manifold pressurizing oil (29) other than the system pump (18). This source of exhaust manifold pressurizing oil (29) may include a flow amplifying device (57) which is activated when the fluid motor (10), in the form of a cylinder, moves a load in the direction of its piston rod end (11) and when the piston rod end (11) of cylinder (10) is subjected to a negative load pressure and when the pressure in the exhaust manifold (25) drops below a certain minimum preselected level. The flow amplifying device (57) is also activated when the cylinder (10) controls a negative type load and when the system pump (18) becomes isolated from the fluid motor (10), in order to conserve the fluid power, generated by the pump (18), for use in control of other system loads (22).