In the previous report, we showed a simple method to identify the approximate transfer function of an instrument as a standard 2nd order system by using self-excited oscillation analysis provided that the output detector's delay in the self-excited oscillation system is negligible.
This paper discusses the effects of output detector's delay on the identified results, and shows a method to identify its approximate transfer function on the condition that the delay is not negligible. The experiments on an electro-hydraulic servo-valve are conducted by means of a self-excited oscillation system in which the flow-rate detector's delay is composed of an analogue electric circuit as a 1st order delay system. Consequently, it is confirmed that the identified frequency transfer functions of an electrohydraulic servo-valve G (jω) almost coincide with its measured frequency characteristics within the frequency region where∠G (jω) is more than-75°, even though the ratio of flow-rate detector's time constant to an equivalent servo-valve's time constant is more than 0.36.

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Under a dynamic supply of pressure and dynamically eccentric loads acting on hydrostatic thrust bearings, the motion and tribological characteristics in mixed to fluid film lubrication are studied theoretically. The effects of supply pressure, loads, eccentricity of loads, time-lag of changes in between the supply pressure and loads, surface roughness, and radial ratio and volume of the recess on the motion of the bearing-pad, pressure distributions, friction, leakage flow rate and power losses are clarified numerically. The conclusions are : The eccentricity of the load increases the inclination of the pad and causes local metallic contact. The time-lag influences the motion of the pad in the low pressure region. The moment-load carrying capacity is increased and the power loss is reduced as the radial ratio of the recess is decreased.

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Experiment was made of cavitation erosion due to the impingement of a cavitating jet using aluminum alloy specimens in petroleum based hydraulic fluid. Clarification was made of the effects of nozzles shape on cavitation erosion. Two short orifices were compared with the cylindrical orifice reported previously. It is clarified that the mass losses using either of the former exceeded that of the latter.
The effects of unsteady flow field on cavitation erosion were also studied for the three orifices. Upstream orifice pressure was changed sinusoidally, its amplitude was less than 0.33 the mean value, 11.9MPa, and frequency, below 100 Hz. Downstream pressure remained essentially unchanged. Consequently, the peak erosion rate was not larger than the estimated as a function of nth power of upstream pressure (n>1). The frequency of upstream pressure caused slight increase in the peak erosion rate.

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This paper describes a pneumatic grasping device capable of performing a similar catching operation for insectivorous plants. Two sets of double membranes, which have the same construction, are aligned, and their movable ends face each other at a distance. A nozzle is attached to movable ends of both sets of membranes, and outside chambers of the double membranes are enclosed and interconnected. Air is fed from a constant low pressure source into the inside chamber of the sets of the membranes and it flows out to the atmosphere from the nozzles. A sensing head of a nozzle-flapper system faces to a moving part of a diaphragm assembly which has two pressure receive chambers, and each is pneumatically connected to one of the inside chambers. The output port of the nozzle-flapper system is connected to the outside chambers of the double membranes.
When an object comes near one of the movable ends, the pressure in the inside chamber of the membrane increases in response to the gap between the attached nozzle and its counterface of the object. The pressure increase causes high pressure in both of the outside chambers by the nozzle-flapper system, and the pressure makes the gap smaller and smaller, due to the elongation of the sets of the membrane. Owing to such regenerative action of the pneumatic circuits, pressure of the chambers increases rapidly up to their supply pressure. The movable ends contact and press on the faces of the object quickly, and they continue to grasp the object with a force proportional to the supply pressure.

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