Violation of The Steady-State Friction behaviour of A Precise Hydraulic Pair Due To Imbalanced Radial Hydrostatic Force

Abstract

Violation of The Steady-State Friction behaviour of A Precise Hydraulic Pair Due To Imbalanced Radial Hydrostatic Force W hat has been presented in the paper is a question of violation of the steady-state friction behaviour of a sliding hydraulic pair due to imbalanced radial hydrostatic force that affects the pair. The origins of hydrostatic radial forces in a sliding pair and the effect of this imbalance have been discussed. Computations have been outlined to illustrate how radial hydrostatic forces affect the cylindrical slide. Reasons for the cylindrical slide getting wedged in the sleeve have also been shown. Qualitative assessment of radial forces on the cylindrical slide located in the sleeve has been carried out, and the amounts of imbalance - shown. The qualitative assessment of radial forces in the precise hydraulic pair included a few characteristic variants of a non-uniform distribution of pressure of the working liquid in the annular clearance between the slide and the sleeve. The ways of reducing the imbalance of radial forces from liquid's pressure that affect the cylindrical slide of the hydraulic pair.

The Ongoing Assessment of the Technical Condition of Avionic Hydraulic Drives on the Basis of Information Received from Means for Unbiased Flight Control of Aircrafts

“…Past experience demonstrates that among all commonly known physical phenomena affecting the technical condition of hydraulic units, the following can be distinguished as the most important ones [3,4]: -mechanical deterioration of hydraulic plunger and barrel mating assemblies due to abrasive and erosive wear of their working surfaces (Fig. 1), -fatigue wear of individual components exposed to the impact of dynamic loads, -ageing of materials, in particular sealing and packing stuff of any type made of elastomeric rubber, caused by various substances used for operation of the units.…”

Theoretical Issues Associated with the Evaluation of the Technical Condition of Avionic Hydraulic Drives on the Basis of Information Received from Means for Unbiased Flight Control of Aircrafts / Teoretyczne Aspekty Oceny Stanu Technicznego Lotniczego Napędu Hydraulicznego Na Podstawie Informacji Ze Środków Obiektywnej Kontroli Lotu

“…Past experience demonstrates that among all commonly known physical phenomena affecting the technical condition of hydraulic units, the following can be distinguished as the most important ones [3,4]: -mechanical deterioration of hydraulic plunger and barrel mating assemblies due to abrasive and erosive wear of their working surfaces, -fatigue wear of individual components exposed to the impact of dynamic loads, -ageing of materials, in particular sealing and packing stuff of any type made of elastomeric rubber, caused by various substances used for operation of the units. First and foremost, the foregoing phenomena lead to an increase of the friction forces and of play between the components of the hydraulic plunger and barrel mating assemblies.…”

“…When the values of the statistical moments, i.e. the expected value m y (t) and the mean square deviation for the specific control parameter of the avionic hydraulic drive are known, it is possible to calculate the average change y śr of that parameter and the confidence intervals for deterioration of that parameter [3,4].…”

Identification of Destructive Processes Affecting Hydraulic Servomechanisms of the Aircraft Control Assist System

“…The slider of the sliding pair in a hydraulic distributor is affected by the following impacts: a) friction forces between a slider and a sleeve caused by obliteration (clogging) of the clearance within a sliding pair or mechanical jamming of a sliding pair (caused by penetration of solid particles into the clearance gap between components of the hydraulic pair) [1,3]. b) hydrodynamic radial forces produced by pressure of fluids in the working gap (design clearance) caused by flow of liquid via the gap [4], c) hydrodynamic axial forces [4,5].…”

“…The radial force generated by the fluid pressure affects the slider of a hydraulic precision pair. When the slider is perfectly cylindrical and its surface is finished to a very high degree of smoothness, all the forces are mutually balanced, both in axial and radial directions and the rubbing surfaces are separated with the film of working fluid [4]. The slider friction in such a pair depends only on the speed of the slider itself and the fluid viscosity.…”