Influence of recess shape on the performance of a capillary compensated circular thrust pad hydrostatic bearing

This exciting new reference text is concerned with fluid power control. It is an ideal reference for the practicing engineer and a textbook for advanced courses in fluid power control. In applications in which large forces and/or torques are required, often with a fast response time, oil-hydraulic control systems are essential. They excel in environmentally difficult applications because the drive part can be designed with no electrical components and they almost always have a more competitive power/weight ratio compared to electrically actuated systems. Fluid power systems have the capability to control several parameters, such as pressure, speed, position, and so on, to a high degree of accuracy at high power levels. In practice there are many exciting challenges facing the fluid power engineer, who now must preferably have a broad skill set.

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Fundamentals of Fluid Power Control

In recent years, health-care industry has received a major boost due to sensors i.e., accelerometers, magnetometers etc., which allow its user to get instant updates about their current health status in indoor/outdoor environments. The real driving force behind the usage of accelerometer has been the fitness industry but it also holds a prominent place in ambient smart home to monitor resident’s life-style. In this paper, we proposed a novel triaxial accelerometer-based human motion detection and recognition system using multiple features and random forest. Triaxial signals have been statistically processed to produce worthy features like variance, positive and negative peaks, and signal magnitude features. The proposed model was evaluated over HMP recognition data sets and achieved satisfactory recognition accuracy of 85.17%. The proposed system is directly applicable to any elderly/children health monitoring system, 3D animated games/movies and examining the indoor behaviors of people at home, malls and offices.

A Wrist Worn Acceleration Based Human Motion Analysis and Classification for Ambient Smart Home System

The numerical developments described in Part 1 are extended to incorporate the consideration of non-Newtonian effects, and fully coupled solutions of the thermal non-Newtonian elastohydrody...

Thermal elastohydrodynamic analysis of circular contacts Part 2: Non-Newtonian model

Tribological study on hydrostatic slipper bearing with annular orifice damper for water hydraulic axial piston motor

On mixed and fluid film lubrication the characteristics of hydrostatic bearings for hydraulic equipment are studied numerically. By applying a mixed lubrication model derived in a previous paper to the bearings, we clarify the effects of the surface roughness, eccentric or moment loads, supply pressure and speed of rotation on the friction, flow rate, and power losses. Introducing the concept of a ratio of hydrostatic balance, we show that the minimum power loss is given as the ratio becomes close to unity

Application of a Mixed Lubrication Model for Hydrostatic Thrust Bearings of Hydraulic Equipment

Mixed lubrication characteristics of hydrostatic thrust bearings are examined experimentally. The effects of the surface roughness, supply pressure, loads, speed of rotation and size of restrictors on the frictional force, leakage-flow rate and power losses are clarified. Introducing the concept of mean pressure based on load-carrying capacity due to asperities, and the ratios of hydrostatic balance and leakage-flow rate, the experimental data can be normalized. Also good agreement is found between theoretical results based on a mixed lubrication model presented in a previous paper and the experiment.

Experiment on Mixed Lubrication of Hydrostatic Thrust Bearings for Hydraulic Equipment

Optimum design of bearing and seal parts for hydraulic equipment

The assumptions of a quadratic temperature profile and mean viscosity across the film, which are frequently used in the analysis of thermal elastohydrodynamic lubrication (EHL), are examined and discussed. Two different approaches for solving the thermal EHL problem are compared for line contact conditions, namely (a) a one-dimensional model based upon both the assumption of a quadratic temperature profile and the adoption of the mean physical properties across the film and (b) a two-dimensional model which includes changes in temperature and physical properties of a lubricant across the film and which takes into account the conditions of reverse flow and heat convection across the film occurring at the inlet region. A multi-grid algorithm is implemented to solve these two conditions. The temperature profile and the general solutions in the conjunction obtained in both approaches are compared. For the one-dimensional model, results reveal that temperature peaks just prior to the inlet of the conju...

On the effects of the temperature profile approximation in thermal Newtonian solutions of elastohydrodynamic lubrication line contacts

This paper presents a time-dependent mathematical model of a hybrid (hydrostatic/hydrodynamic) thrust pad bearing as a slipper of swash-plate type axial piston pumps and motors for the use of tap water under mixed and fluid fihn lubrication condition. Effects are examined of the load eccentricity, time-lag of changes in the supply pressure and load, surface roughness, recess volume, and the revolution radius. The bearing's motion is simulated three-dimensionally, including roughness interaction and asperity contact. Solutions are obtained regarding the friction, flow rate, power loss, and stiffness. Calculations indicate that the eccentric load causes local contacts. The preceding change in the load poses a larger motion of the bearing. The hydrodynamic effect becomes marked as the revolution radius increases. As the recess volume increases, the bearing stiffness decreases.

Toshiharu Kazama

Papers

Application of a Mixed Lubrication Model for Hydrostatic Thrust Bearings of Hydraulic Equipment

Experiment on Mixed Lubrication of Hydrostatic Thrust Bearings for Hydraulic Equipment

Optimum design of bearing and seal parts for hydraulic equipment

On the effects of the temperature profile approximation in thermal Newtonian solutions of elastohydrodynamic lubrication line contacts

Numerical simulation of a slipper model for water hydraulic pumps/motors in mixed lubrication