Abstract: To provide a semiconductor memory device having an ECC circuit whereof checker-data inspection of memory cells in the user areas and the ECC areas can be performed at once, the ECC code generation circuit generates the ECC code of six bits whereof logic of each bit has XOR logic of each of six different combinations of 15 bits of the data set of 32 bits, and addresses in every user areas of the bit-columns are arranged in an order of 1, 4, 2, 5, 3, 6, . . . , b, f. When a checkerboard pattern is written, a first data set having 32 bits of logic ‘0’ and a second data set having 32 bits of logic ‘1’ are written alternately, in addresses 4n to 4n+3 and 4(n+1) to 4(n+1)+3 of the user areas on odd-numbered word-lines, and written alternately on even-numbered word-lines in an inverse order of the odd-numbered word-lines, when checker-data inspection of the memory-cell array is performed, n being an integer not less than 0.

Abstract: This invention relates to a fault diagnosis system for hydraulic pumps in a work vehicle, which is economical and permits sure identification of one or more trouble-developed ones of the hydraulic pumps.Pressure sensors 61-64 are arranged on pressurized fluid lines 30,40, which extend to a tank T from points immediately out of center bypasses of flow control valves 21,231-234,451-454,26 communicated to hydraulic pumps 1-6. Solenoid-operated directional control valves 51-56 are interposed in input circuits of individual regulators 11-16 so that, upon excitation, a pressure of a pilot pump 7 is introduced into the regulators 11-16. When all the flow control valves are brought into neutral positions thereof and a determination is instructed through a switch 80, one of the solenoid-operated directional control valves is excited by a signal from a processor 70 so that pressurized fluid is delivered at a maximum flow rate from the corresponding hydraulic pump.

Abstract: Pressure adjusting valves (9A, 9B) control outlet pressures of variable throttle portions (8a) of directional control valves (8A, 8B) of closed center type to be kept substantially equal to a maximum load pressure detected by a detecting line (13). A variable throttle valve (40) and a pressure adjusting valve (41) are disposed in a bypass line (5) branched from a pump supply line (3) for controlling an outlet pressure of the variable throttle valve (40) to be also kept substantially equal to the maximum load pressure. The variable throttle valve (40) has an opening area controlled to be reduced with an increase in the input amount by which a control lever unit is operated, and a pump delivery rate is controlled by a tilting control device (2n) to become a flow rate corresponding to the input amount of the control lever unit.

Abstract: A flow control system is arranged in a hydraulic circuit provided with a variable displacement hydraulic pump, plural actuators and a pump controller. The pump controller controls the displacement of the pump so that a delivery pressure becomes higher by a predetermined value than a maximum load pressure of the plural actuators, whereby the flow rate of pressure oil to the actuators is controlled. The system includes plural valve units connected between the pump and the actuators. Each valve unit has an operating and correcting variable restrictors. The system also includes pressure compensation valves, which are each arranged on an upstream side of a restrictor group consisting of the operating and correcting variable restrictors.

Abstract: A hydraulic recovery device in a hydraulic system having a pump (1) driving a plurality of actuators through a plurality of control valves (2, 3), the hydraulic recovery device comprising a variable resistance valve (6, 60) in a first line being controlled by a control signal (Px), a third line, a check valve (7) disposed in the third line for allowing the hydraulic fluid to flow only in a direction from the first line toward the second line.

Abstract: A hydraulic control valve apparatus including a flow control valve having a pair of variable throttles, a feeder passage, a pair of load passages, directional control valve devices comprise a seat valve having a seat valve body movably disposed in a housing to form an auxiliary variable throttle in the feeder passage, and a control variable throttle (33) formed in the seat valve body for changing an opening area in accordance with an amount of movement of the seat valve body; (b) a pilot line (24, 29-31, 35-37) for communicating a portion (7C) of the feeder passage upstream of the auxiliary variable throttle with a downstream portion (7A, 7B) of the feeder passage through the control variable throttle to determine the amount of movement of the seat valve body in accordance with a flow rate of the hydraulic fluid passing through the pilot line; and (c) pilot flow control (400; 401; 403; 405; 406; 407; 408) having a pilot variable throttle (45) disposed in the pilot line and input (800; 52-59; 159, 54-59; 231A,

Abstract: A hydraulic drive system for hydraulic working machines has a variable displacement hydraulic pump, at least one actuator driven by the hydraulic fluid, a directional control valve of center bypass type for controlling the flow of the hydraulic fluid, a center bypass line for connecting the center bypass passage of the control valve to a reservoir and a fixed restrictor disposed in the center bypass line. A first control signal that determines a first target displacement of the hydraulic pump is determined by using the pressure generated by the fixed restrictor. A second control signal is generated for determining a second target displacement of a hydraulic pump. A third control signal, which is the larger one of the first and second control signals, provides a target displacement that is applied to a pump regulator that controls the displacement of the hydraulic pump.

Abstract: In a hydraulic drive system for a construction machine, first flow control mechanism includes first and second flow control valves (11a, 11b) and first interlock mechanism (54, 55) for interlocking the first and second flow control valves with first directional control mechanism (7), and second flow control mechanism includes third and fourth flow control valves (12a, 12b) and second interlock mechanism (56, 57) for interlocking the third and fourth flow control valves with second directional control mechanism (9). First pressure control mechanism includes at least first pressure control valve (13a) operated in response to a pressure signal in a valve-closing direction, and second pressure control mechanism includes only second pressure control valve (15b) operated in response to the pressure signal in a valve-closing direction.

Abstract: A valve apparatus (30) of a hydraulic valve system has a plurality of directional control valves (78, 79) that control the flow of the hydraulic fluid to a plurality of actuators (34, 35). Check valves (59, 60) are provided for taking out, as a first control pressure, a maximum load pressure among load pressures of the plurality of actuators, first pressure generating devices (89, 91) for generating second control pressures different from the first control pressure, and second pressure generating devices (90, 92) for generating third control pressures different from said first and second control pressures.

Abstract: A variable displacement hydraulic pump and a hydraulic motor are connected in a closed circuit. A pressure oil supply means includes the variable displacement hydraulic pump and a tilting controlling means for controlling a tilt angle of the hydraulic pump and supplies an amount of pressure oil corresponding to the tilt angle of the hydraulic pump to the hydraulic motor. When rotation of a prime mover is detected by a rotation detecting means, an opening and closing valve is changed over to a first position in which the pressure oil supply means is permitted to supply pressure oil. When stopping of the prime mover is detected by the rotation detecting means, the opening and closing valve is changed to a second position in which the pressure oil supply means is inhibited from supplying pressure oil.

Abstract: A hydraulic drive system is equipped with an engine, a plurality of hydraulic pumps adapted to be driven by the engine and including a variable displacement hydraulic pump provided with a displacement varying mechanism, a hydraulic motor connected to the variable displacement pump, a hydraulic actuator for actuating the displacement varying mechanism of the variable displacement hydraulic pump, a working fluid feeding means for feeding the hydraulic actuator with a hydraulic fluid of a pressure according to the degree of control of an accelerator lever which is adapted to instruct a target revolution number of the engine, and a low-pressure circuit for allowing the hydraulic fluid to be discharged therethrough from the hydraulic actuator.

Abstract: A solenoid operated valve apparatus in which a solenoid device includes an inner yoke, a plunger guide disposed in the opposed relationship with the inner yoke, a plunger movably accommodated in s space formed between the inner yoke and the plunger guide, a bobbin frame disposed to surround the inner yoke and said plunger guide, a coil wound around the bobbin frame, and an outer yoke disposed to surround the coil. The bobbin frame is made of a polymeric material, and is adhered to the inner yoke and the plunger guide in a unitary structure.

Abstract: This invention relates to a device for supporting a lift roll for a fork lift truck of the type in which the thrust in the fore and aft direction and in the transverse direction is supported solely by a lift roll, the contact pressure of the lateral side of the outer race with respect to the pressure-receiving section is adjusted by an adjustment screw.

Abstract: A hydraulic drive circuit system is equipped with an accelerator pedal and an accelerator lever for respectively instructing target revolution numbers for an engine, a link plate for selecting greater one of the instruction values, and a linkage and a switch for controlling valves respectively so as to close the flow passage of a line interposed between a charge pump and a low pressure line irrespective of the instruction value of the accelerator pedal when the accelerator lever has not been controlled but for controlling the valves so as to restrict the flow passage of the line in accordance with the instruction value of the accelerator pedal when the accelerator lever has been controlled.

Abstract: A flow control valve apparatus includes a housing including a main fluid passage having an inlet port and an outlet port; a main valve disposed between the inlet port and the outlet port for allowing or shutting off communication between the inlet port and the outlet port; a backpressure chamber formed between an inner wall of the housing and a rear portion of a valve member of the main valve, the backpressure chamber communicating with the inlet port through an orifice; an auxiliary passage for placing the backpressure chamber in communication with the outlet port; and a pivot valve for actuating the main valve by controlling the opening and closing of the auxiliary passage and varying the fluid pressure in the backpressure chamber. A differential pressure generating means is disposed in the main fluid passage for generating differential pressures that correspond to the flow rate in the main fluid passage.