Abstract: Simultaneous operation efficiency in a case where a plurality of actuators are operated by one or a plurality of hydraulic pumps is improved. A delivery pressure passage (1a) of one hydraulic pump (1) and that (1a) of the other hydraulic pump (1) communicate with each other through a first short-circuit passage (39) via a pair of check valves (38, 38), and an unload valve (40) is provided in this first short-circuit passage (39). The load pressure introduction passages (6, 6) on the left and right hydraulic pumps (1, 1) communicate with each other through a second short-circuit passage (36) via a pair of check valves (35, 35), and a relief valve (37) is provided in this short-circuit passage (36).

Abstract: A hydraulic circuit including a pressure compensating valve, which aims at preventing the delay in operation of the valve due to the time required for the inflow of fluid in amount corresponding to stroke volume thereof, thereby improving the response of thereof. This hydraulic circuit includes a pressure compensating valve (3) provided between the delivery side of a hydraulic pump (1) and the inlet of a directional control valve (4), the pressure compensating valve (3) being arranged to be urged by the pressure applied to first pressure receiving portion (6) to position (D) where the area of opening thereof is kept maximum, and also urged by the pressure applied to second pressure receiving portion (8) to position (E) where the area of opening thereof is kept minimum, the portions (6) and (8) being connected with the outlet and inlet sides of the valve (4).

Abstract: This invention has for its aim to provide a hydraulic circuit system arranged such that, even at the time of commencement of drive of a hydraulic actuator with a large inertia, a slow rise in the drive pressure can be achieved, thereby preventing the occurrence of hunting phenomenon. The hydraulic circuit system according to the present invention comprises a plurality of operating valves (15) provided in a discharge conduit (10a) of a hydraulic pump (10), and pressure compensating valves (18) provided in connection conduits between these operating valves (15) and respective hydraulic actuators (16), wherein each of the pressure compensating valves (18) is set at a highest value of load pressures of each of the hydraulic actuators (16), and the displacement of the pump is controlled by a change-over valve (14) adapted to be actuated by the difference between the pump discharge pressure and the load pressure.

Abstract: A hydraulic circuit for a swivel working machine, in which the operation of the working unit is speeded up when the swiveling body and the working unit are simultaneously operated, includes, for this purpose, first and second operating valves (15.sub.1 and 15.sub.2) connecting the delivery conduit of a hydraulic pump (10) to a swiveling hydraulic motor (16.sub.1) and to a working unit cylinder (16.sub.2), and pressure compensating valves (18) provided between the first operating valve (15.sub.1) and the swiveling hydraulic motor (16.sub.1) and between the second operating valve (15.sub.2) and the working unit cylinder (16.sub.2), the load pressure of the swiveling hydraulic motor (16.sub.1) and the load pressure of the working unit cylinder (16.sub.

Abstract: This invention aims at providing a hydraulic circuit apparatus for supplying pressurized fluid into cylinders for a work implement arranged such that during normal operation of the work implement the flow rate of fluid discharged by a pump is controlled such that the difference between the discharge pressure of the pump and the load pressure is always kept constant, whilst during inching operation of the work implement the flow rate of fluid discharged by the pump is reduced.

Abstract: An operation valve having a pressure compensation valve of relatively simple non-complicated internal body structure. In the valve body, a load pressure introducing passage, a check valve and a restriction are formed inside the spool comprising the operation valve. An intermediate pressure between an inlet pressure and an outlet pressure of the compensation valve which is arranged in the valve body, may be supplied to a pressure receiving section of the pressure compensation valve through an oil hole of the spool. The operation valve with the pressure compensation valve is of simple construction and may be easily manufactured.

Abstract: In the hydraulic apparatus (1) according to a first aspect of the present invention, mid-pressures between the inlet side and outlet side pressures of a first and a second pressure compensating valves (4, 4') are permitted to act on the flow rate decreasing side pressure receiving surfaces (4b, 4b') thereof through first and second mid-pressure supplying means (13, 13'), thereby restraining operational error and malfunction of the pressure compensating valves (4, 4'). In the hydraulic apparatus (20) according to a second aspect of the present invention. when actuating valves are made to assume neutral position, holding pressures of hydraulic actuators (5, 5') are permitted to act on flow rate decreasing side pressure receiving surfaces (4b, 4b') of pressure compensating valves (4), (4') so that spools of the pressure compensating valves are held at compensating position, thereby improving the response of the hydraulic actuators (5, 5') to lever actuation.

Abstract: This invention provides a hydraulic circuit system capable of reducing the flow rate distribution error in supplying pressurized fluid from a single hydraulic pump into a plurality of hydraulic actuators, and also supplying pressurized fluid quickly. The circuit is simplified to reduce manufacturing costs.

Abstract: This invention provides a hydraulic circuit apparatus arranged such that when each of operating valves is operated suddenly, the stability of each of actuators is improved, and when the operating valves are kept at their neutral positions, the flow rate of fluid discharged by a variable displacement pump is increased to improve the response of the hydraulic circuit, and when the actuators are supplied with pressurized fluid, pressure compensation is made by pressure compensating valves.

Abstract: A hydraulic circuit arranged to prevent the load pressure in one of the hydraulic actuators at the time of starting from becoming abnormally high thereby preventing fluid under pressure from being relieved by the safety valve when a plurality of hydraulic actuators are operated at the same time, wherein the function of one of the pressure compensating valves is temporarily enhanced by introducing the load pressure in the hydraulic actuator so as to supply a large quantity of fluid under pressure to the hydraulic actuator connected to the pressure compensating valve so that the operating speed of the hydraulic actuator can be increased.

Abstract: An apparatus for measuring the amount of oxygen in a sample gas, which is suited for quantifying small amount of oxygen in a sample gas. The apparatus of the present invention comprises a yellow phosphorus vapor-providing section in which yellow phosphorus is retained, by which the vapor of the yellow phosphorus is supplied and by which the amount of the vapor of the yellow phosphorus is controlled. The apparatus further comprises a reaction chamber connected to the yellow phosphorus vapor-providing section, in which the light-emitting reaction between the oxygen in the sample and the vapor of the yellow phosphorus is conducted, and a sample gas-supplying section. The amount of the oxygen in the sample gas is determined by measuring the intensity of the light emitted by the reaction by a light intensity-measuring device.

Abstract: A method for measuring the amount of oxygen in a sample gas is suited for quantifying small amount of oxygen in a sample gas. The method of the present invention comprises reacting the oxygen and vapor of yellow phosphorus under a vapor pressure of the yellow phosphorus which is lower than the saturated vapor pressure of the yellow phosphorus at room temperature; and measuring the intensity of light emitted by the reaction. The amount of the oxygen in the sample gas is determined by measuring the intensity of the light emitted by the reaction by a light intensity-measuring device.

Abstract: A brake release mechanism for a spring-loaded, normally applied vehicle brake releasable by system hydraulic pressure when the system is disabled includes a pilot-operated brake release valve for isolating the brake from the disabled system, a brake control valve disposed between the system and the brake, and a manual hydraulic pump communicating with the brake for supplying fluid pressure thereto. A pilot-operated shunt valve is provided for shunting a hydraulic motor associated with the brake to allow free turning thereof during towing.

Abstract: A fluid operated pump displacement control system is provided wherein a self pressure is defined as a first control signal, and characterized in that an arbitrary switchable second control signal different from the first control signal is added to the first control signal, and a displacement is adapted to be switched to a displacement corresponding to a value of the second control signal as added to the first control signal. Further, a fluid operated pump displacement control system is provided comprising a control circuit connected to respective displacement control devices of variable displacement pumps and adapted to be operated by discharge pressure fluid from a discrete control pump.

Abstract: A control system for a variable displacement pump or pumps driven by a vehicular engine for supplying pressurized fluid to implement actuators via implement control valves. The engine has several output conditions each with a different output torque characteristic. The control system includes a servomechanism comprising a servoactuator section coupled to the pump for varying the per cycle displacement thereof, a servovalve section for operating the servoactuator section by fluid pressure from a fixed displacement pump, and a control section for actuating the servovalve section. The servomechanism control section is fluid operated from a torque control valve, which delivers a controlled degree of fluid pressure from the fixed displacement pump to the control section in order to correspondingly vary the torque requirement of the variable displacement pump.

Abstract: A control system for variable displacement hydraulic pumps for use in a hydraulically operated construction vehicle having a fixed displacement hydraulic pump, a plurality of reducing valves operatively interlocked with work implement control valve units of the vehicle disposed on the delivery sides of the variable displacement pumps, control sections for controlling respective flow rate of the variable displacement pumps and equipment for exerting delivery pressures of both the fixed and variable displacement pumps and output pressure of the reducing valve on the control units. The control system exhibits three control functions, i.e., flow control for varying the angle of the swash plate of the variable displacement pump in proportion to the manipulating position of the respective work implement controlling valve, constant torque control in proportion to the delivery pressures of the variable displacement pumps, and cut-off control for reducing relief losses.

Abstract: A hydrostatic transmission has an engine-driven, bidirectional, variable-displacement drive pump connected in circuit with a bidirectional, variable-displacement propelling motor. A charging pump is also connected to the circuit of the drive pump and the propelling motor. A brake assembly normally locks the output shaft of the propelling motor against rotation and releases same only while being supplied with a hydraulic brake release signal. The control system for the hydrostatic transmission comprises a speed control valve actuated manually to deliver fluid pressure signals to servo controls for adjusting the outputs from the drive pump and the propelling motor, and a brake control valve pilot-operated to deliver the brake release signal to the brake assembly. Also included are a charge sensor valve and a speed control sensor valve.

Abstract: A lever hoist comprises a change gear provided in a driving shaft for driving a sheave for winding-up a chain or rope for a load, an operating lever rockably driven by a hand, winding-up and winding-off driving pawls engageable with teeth of the change gear and changeable in response to the purpose of hoisting or lowering the load, and a braking assembly for preventing the change gear from being driven by a gravity of the load and having a spring for releasing the braking assembly. According to the invention the lever hoist further comprises a brake spring control member rotatably fitted on the driving shaft, a brake clamping spring arranged between the driving member and the brake spring control member, and a direction change transmission mechanism for transforming rotation of the brake spring control member into axial urging force of the brake clamping spring.

Abstract: According to the present invention volatile hydrides such as diborane, arsine, phosphine and the like are made to react with mercuric oxide at room temperature to produced mercury atom, the concentration of which is thereafter measured and the concentration of volatile hydrides is determined in accordance with the corresponding measured mercury atom concentration. As the measuring apparatus according to the present invention is made to measure mercury atom, it can easily detect even extremely small quantity of substances such as volatile hydrides and respond quickly, thus enabling the apparatus to be suitably used as a monitor in semiconductor industry.

Abstract: According to the present invention volatile hydrides such as diborane, arsine, phosphine and the like are made to react with mercuric oxide at an ordinary temperature to produce mercury atoms, the concentration of which is thereafter measured and the concentration of volatile hydrides is determined in accordance with the corresponding measured mercury atom concentration. As the measuring apparatus according to the present invention is made to measure mercury atoms, it can easily detect even extremely small quantity of substances such as volatile hydrides and respond quickly, thus enabling the apparatus being suitably used as a monitor in the semiconductor industry.