Abstract: A servovalve apparatus comprising a servovalve and a force motor operatively connected to a valve element of the servovalve for driving the valve element. The force motor includes an annular magnet, and first and second members cooperating with each other to define therebetween an annular gap concentric with the annular magnet. A cylindrical coil operatively connected to the valve element is disposed in the annular gap in concentric relation therewith and is reciprocated within the annular gap in response to the electric current passing through the coil. First and second cylindrical resilient members thermally connect one and the other axial ends of the cylindrical coil to first and second stoppers, respectively, to transmit the Joule heat generated by the coil to the first and second stoppers.

Abstract: A direct drive type servo motor in which a spool is driven directly by a force motor, the force of the force motor being balanced by the reactional force generated by a resilient member to stabilize the position of the spool to control the flow of working fluid. The resilient member is constituted by a metallic cylindrical member having holes formed in the outer peripheral surface thereof. The holes are arranged such that, when the force is applied to the cylindrical member in the axial direction, the cylindrical member produces an axial reactional force. In consequence, the generation of force component which would act to press the spool against the sleeve is avoided to reduce the friction between the spool and the sleeve to permit a smooth movement of the spool, while allowing the resilient member to have a high spring constant to improve the response characteristic of the servo valve.

Abstract: A hydraulic operating apparatus including an actuating cylinder having a piston arranged therein and moved by a fluid under high pressure further includes a control valve having only one metallic seal whether the piston is at its upper or lower positions. The control valve is operative to apply the fluid under high pressure to a pressure receiving surface of the piston on the opposite side of a piston rod to move the piston in a direction in which the piston rod extends from the piston and to discharge the fluid existent on the opposite side of the piston rod from the actuating cylinder to move the piston in a direction opposite the direction in which the piston rod extends from the piston.

Abstract: A fluid pressure servo valve assembly driven by a pilot servo valve assembly and having a valve body formed therein with a cylindrical bore, input ports and output ports opening in the cylindrical bore, a spool valve member fitted in the cylindrical bore for axial reciprocatory movement and including axially spaced lands for connecting and disconnecting the input ports with the output ports as the spool valve member moves in axial reciprocatory movement in the cylindrical bore, a sealed annular space defined by an annular recess formed in the peripheral surface of the cylindrical bore of the valve body and an outer peripheral surface of one of the lands of the spool valve member, a piston member integrally connected to the outer periphery of the one of the lands of the spool valve member and extending radially outwardly therefrom into the annular space to divide the same into two pressure chambers, and passages for communicating the two pressure chambers with the pilot servo valve assembly.

Abstract: A fluid pressure drive device including a primary drive portion operated by receiving an operational command, and a secondary drive portion operated due to the operation of the primary drive portion. In this fluid pressure drive device, at least parts of movable members in the above both drive portions are overlapped so as to shorten the lengths of fluid passages. As a result, a time interval from the receiving of an operational command until the generation of a drive force in the final drive portion, i.e., a response time of the drive device may be shortened.

Abstract: A roll eccentricity control apparatus for use with an automatic gage control device of gage meter type for a rolling mill comprising rolls for rolling the material to be rolled, a hydraulic jack for providing the rolls with rolling pressure, a flow rate control valve and a valve control device for adjusting the roll gap by controlling the quantity of oil in the hydraulic jack, a setting device for applying a desired gage command to the valve control device and a gap detector for detecting the roll gap and feeding back the detected value to the valve control device; said apparatus comprising a correlation detector for detecting the correlation between the rolling pressure and a reference signal wave obtained from a roll rotation signal, a memory for storing the output of the correlation detector, and a device for retrieving the correlation output stored in the memory by the use of a signal associated with the rotation of the rolls and applying a command to the gate control device.

Abstract: A gage control system for a rolling mill for compensating for variation in the thickness of rolled material due to variations in the rolling load or pressure. In the system, the roll eccentricity frequency produced by the eccentricity of the rolls is detected and utilized for softening the effective rigidity or stiffness of the mill, that is, weakening the apparent mill modulus by control means according to the frequency of roll eccentricity. To this end, a positive feed back path including an eccentricity control unit is provided in parallel with a feed back path of the rolling pressure signal of a gage control circuitry of the so-called BISRA system. The eccentricity control unit serves to detect the roll eccentricity on the basis of a correlation principle and compensate for or cancel the effects of the feed back of the rolling pressure upon the occurrence of the roll eccentricity.

Abstract: In an alternating current dynamoelectro machine, the rotor core and/or stator core are axially divided into a plurality of blocks, adjacent blocks of the rotor core and/or those of the stator core are fixed to the rotor shaft and to the motor frame, respectively, at different positions on circumference of respective blocks, whereby an interactive vibration energy between the blocks is absorbed by relative vibrations produced between the adjacent blocks so that vibrations and noises of the machine can be reduced.

Abstract: A floor level correcting device used in a hydraulic elevator comprises means for electrically detecting the vertical position of the elevator cage with respect to the floor landing and driving means for level correction, provided independent of a main power unit for driving the elevator cage. The detecting means comprises means provided in the elevator shaft and means provided in the elevator cage which detect, in co-operation with each other, the level of the cage with respect to the floor landing of the building in particular whether the cage is stopped in the proper landing position or shifted therefrom, so as to produce an electrical signal in accordance with the detected cage level to transmit the signal to the driving means for level correction.

Abstract: A sound preventive device for use in an elevator including: a skirt extending from the lower edge of the sill of a cage of an elevator and having a length greater than the difference between the height of the floor and the height of the cage and a width substantially the same as that of the cage; and guide plates which extend upwards and downwards respectively from the rear plate of the cage, the aforesaid guide plates having widths substantially the same as that of the rear plate, whereby abrupt changes in air developing above and below the cage may be minimized by means of the skirt and guide plates.