摘要:
A device for controlling a working arm of a working machine, which is capable of releasing the pressure of the actuation fluid confined in the actuation cylinder of the working arm device at a predetermined pressure lower than the set pressure and of controlling the opening/closing of the cylinder relief valve. The device comprises releasing means for a releasing a pressurized fluid feed/drain circuit of an actuation cylinder of a working arm device at a predetermined pressure lower than a set pressure of a cylinder relief valve provided for said feed/drain circuit and a control means for controlling the opening/closing of the releasing means.
摘要:
A pressure control valve 1 for supplying a pressure fluid, the pressure of which has been regulated, to a supply passage 61 in a solenoid valve aggregate 6 formed of a plurality of solenoid valves 60 arranged said by side in a line. tHE VALVE 1 is placed between a supply-exhaust block 5 for supplying and discharging a pressure fluid from and to the outside and the solenoid valve aggregate 6. A control valve body 10 of the pressure control valve 1 is provided with an input port in communication with a supply port 51 of the supply-exhaust block 5, an output port in communication with a supply passage 61 installed through the solenoid valve aggregate 6, a pressure regulating mechanism which regulates the pressure of the pressure fluid supplied from the supply port 51 and outputs a secondary pressure to the supply passage 61 of the solenoid valve aggregate 6 through the output port, and an exhaust passage that directly links a discharge passage of the solenoid valve aggregate 6 and an exhaust port 52 of the supply-exhaust block.
摘要:
The invention concerns a positioning drive which is used in particular for machine tools and which comprises a hydraulic motor (10). The hydraulic motor comprises: a control disc (17) which is rotatable with a motor shaft (18) and is provided with a radial cam (19); a control valve (12) which, with the hydraulic motor (10), forms a unit with a preferably multi-part housing (37, 46) and comprises a valve piston (15) which can be displaced between a plurality of settings; a control component (16) by means of which the valve piston (15) can be supported on the control disc (17); and an adjusting component (65) which is operatively disposed between the control component (16) and the valve piston (15) and is coaxial to the latter. The relative position between the valve piston (15) and control component (16) can be varied by the relative adjustment of the adjusting component (65) to the valve piston (15). The position of the adjusting component (65) relative to the valve piston (15) can be secured by a releasable securing component. In order to be able to adjust the position between the valve piston (15) and the control component (16) very simply, the outer of the two parts, valve piston (15) and adjusting component (65), is guided outwards through the housing and the securing component (72, 80) is accessible externally of the housing.
摘要:
In a construction machine of a small rotational inertia such as an intra-width swing machine or a small-sized excavator, a rotative operability varies depending on the posture of a working attachment, and in a reduced state of reach, a change in rotating force is oversensitive to the operation of a working lever, so operation is difficult. To cope with this point, means for detecting the operation of a rotating direction control valve is provided and an outlet of a center bypassing oil path in the rotating direction control valve and an oil tank are brought into communication with each other through a cut-off valve used for controlling the bleed-off thereof. Further, a pilot port of the cut-off valve and a source of a pilot oil pressure are brought into communication with each other through an electromagnetic proportional pressure reducing valve, and an operation command signal is issued from a controller to the electromagnetic proportional pressure control valve to control the acceleration of rotation and the maximum rotating speed.
摘要:
A crawler loader or other large industrial earthmoving machine has a hydraulic propulsion system comprising at least two hydraulic motors (26, 28) which are powered from a pump (44) to drive a common load, namely its tracks (24). Each motor (26, 28) of the hydraulic propulsion system is provided with two compensating valve assemblies (30, 32 and 34, 36). Each compensating valve assembly has a compensating spool (48, 50, 52, 54) and a shuttle spool (56, 58, 60, 62) to provide accurate control of the hydraulic motors (26, 28). In each pair of compensating valve assemblies (30, 32 and 34, 36), there is a forward compensating valve assembly (30, 34) and a backward valve assembly (32, 36) respectively controlling forward and backward movement of the associated hydraulic motor (26, 28). Between both forward compensating valve assemblies (30, 34) and the respective hydraulic motors (26, 28), the compensating valve assemblies (30, etc.) are fluidically coupled to one another by a small hydraulic communication line (98) that better equalizes hydraulic fluid flow to the motors (26, 28) and prevents domination of one forward compensating valve assembly over the other. Similarly, the backward compensating valve assemblies (32, 36) are provided with an identical small hydraulic communication line (100) accomplishing the same results.
摘要:
Transducteur de pression à commande pneumatique servant à actionner des organes hydrauliques de travail et pourvu d'un cylindre moteur double; sur un de ses côtés il y a un cylindre actionné pneumatiquement, sur l'autre de ses côtés un cylindre à action hydraulique; il est aussi pourvu de moyens de travail hydrauliques raccordés au côté hydraulique. L'essentiel de l'invention consiste en la présence d'une soupape de commande reliée à la chambre primaire qui se trouve devant le piston du cylindre pneumatique du cylindre moteur, soupape qui est en liaison de manoeuvre avec une soupape de démarrage tout en étant reliée par une soupape d'étranglement de retenue avec une autre soupape, et d'autre part en étant reliée par l'entremise d'un clapet de drainage avec le réservoir hydraulique, respectivement par la soupape avec la chambre secondaire du cylindre pneumatique. Une autre caractéristique essentielle consiste en ce que la soupape de commande est reliée par la soupape d'étranglement de retenue du réservoir hydraulique avec le cylindre hydraulique du cylindre moteur double, pour permettre ainsi une obturation à l'aide du piston hydraulique. La conduite située entre la soupape et le cylindre se trouve en liaison de commande avec la soupape de commande par l'entremise d'une soupape d'étranglement de retenue supplémentaire. Le transducteur de pression selon l'invention représente un dispositif relativement bon marché à structure unitaire et simple, à l'aide duquel les organes hydrauliques de travail les plus divers peuvent être actionnés d'une façon qui est déterminée par les organes de travail appliqués ainsi que par le mode d'opération assujetti à la tâche à accomplir.
摘要:
A hydraulic system for an access arrangement having a platform configured for movement between a deployed position and a stowed position, the hydraulic system including: at least one hydraulic power unit configured to urge hydraulic fluid through a hydraulic circuit; at least one hydraulic cylinder directly or indirectly connected to a portion of the platform and configured to urge the platform towards at least one of the stowed position and the deployed position, wherein the at least one hydraulic cylinder is in fluid communication with the hydraulic power unit; and a pressure regulating valve in a path between the at least one hydraulic power unit and the at least one hydraulic cylinder, wherein the pressure regulating valve is operable to prevent the at least one hydraulic cylinder from urging the platform to the stowed position if a load on the platform exceeds a specified threshold.
摘要:
A hydraulic circuit for a construction machine including a center bypass passage, into which a pressurized oil discharged from a hydraulic pump may be supplied, including a directional control valve group including a plurality of directional control valves arranged in tandem with the center bypass passage; and a bleed-off valve arranged in the center bypass passage on a downstream side of the directional control valve group, wherein each directional control valve includes a first internal passage for causing the pressurized oil supplied to the directional control valve to flow out to the center bypass passage and a second internal passage for supplying the pressurized oil to a cylinder port, wherein a parallel passage is formed by the center bypass passage and the first internal passage by causing, by the first internal passage, the pressurized oil discharged from the hydraulic pump to flow out to the center bypass passage on the downstream side of the directional control valve, wherein the second internal passage supplies the pressurized oil from the center bypass passage through an opening of a spool and/or the bypass passage to the cylinder port.