Measurements of the underlap for four-way valves gave results that the underlap was not only uneven but also geometrically asymmetric for some four-way valves. Both the unevenness and the asymmetricity have considerable influence on the characteristics of the valve-controlled cylinder.
In addition to the unevennesses i=(Δ₁/Δ)- 1, i= (Δ'₁/Δ')-1, the asymmetricity η=Δ'₁/Δ is introduced for a valve, where Δ, Δ' are the mean underlaps of the left side and the right side three-way valves and Δ₁, Δ'₁ are the underlaps on the supply sides. represents the right side.
Considering i, η and Δ of a valve, the frequency response of a valve-controlled cylinder with viscous friction, Coulomb friction and mass load was theoretically analyzed where the flow versus pressure characteristic curves were approximated partially as polynomials of degree 3 of the pressure.
The tendency shown by the theoretical results agreed fairly well with that of the experimental results. The frequency characteristics of (piston velocity)/(spool displacement) = V(jω)/ Y(jω)show the same tendency for an asymmetric valve as that for a symmetric valve. But, for the case where an asymmetric valve is used, there is null shift of the valve ( δο) for avoiding the piston drift. δο changes in proportion to i, and |δο| becomes larger according to the increase in η (for η>1) or 1/η (for η <1).δο changes little for the changes in Δ and frequency ω.

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円衝絞りの非定常キャビテーションについての実験結果を示す。実験は二つの流動状態,(i)Q一定, すなわち流量を一定に保って絞り出入口圧力をステップ状に変えた場合, (ii)P₁一定, すなわち入口圧力を一定に保って出口圧力と流量をステップ状に変える場合とについて行った.
遅れ時間に及ぼす油温,圧力,絞り径などの影響を検討した結果, 絞り入口までの気ほう核の溶解の度合が, 非定常キャピテーションに著しい影響を及ぼすことが分かった.
拡散や蒸発による気ほうの目視できる最小の大きさになるまでの所要時間を理論的に求め, 絞りのキャピテーシションでは蒸発による成長が主要な役割を負うことを示した.

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