Free rotational aerophones such as the bullroarer, which consists of a wooden slat whirled around on the end of a string, and which emits a loud pulsating roar, have been used in many ancient and traditional societies for ceremonial purposes. This article presents an experimental and theoretical investigation of this instrument. The aerodynamics of rotational behavior is elucidated, and relates...

Abstract—This study presents a procedure for friction calculation of column electric power steering (C-EPS) system which affects handling and comfort in driving. The friction losses estimation is obtained from experimental tests and mathematical calculation. Parts in C-EPS mainly involved in friction losses are bearings and worm gear. In the theoretical approach, the gear geometry and Hertz law...

PURPOSE Among the different resistances occurring during wheelchair locomotion and that limit the user autonomy, bearing resistance is generally neglected, based on a few studies carried out in static conditions and by manufacturer's assertion. Therefore, no special attention is generally paid to the mounting and the maintenance of manual wheelchair bearings. However, the effect of inadequate m...

This article deals with a possibility of how to determine a power dissipation in a rotating machine. It divides losses in three parts according to their origin – losses arising around the rotating disc, in bearings, and by a friction of a shaft surface due to viscosity. A precise determination of the power dissipation is important when evaluating the efficiency of the whole device. The procedur...

A method is proposed for evaluating the dynamical friction of linear bearings, whose motion is not perfectly linear due to some play in its internal mechanism. In this method, the moving part of a linear bearing is made to move freely, and the force acting on the moving part is measured as the inertial force given by the product of its mass and the acceleration of its centre of gravity. To eval...

Journal bearings in hermetic reciprocating compressors are analyzed experimentally as well as numerically. The motor current and the load applied to the bearing are measured to obtain the performance curve of the journal bearing, from which the critical Sommerfeld number is derived. In the numerical analysis, the Reynolds equation and equilibrium equations of the journal center are solved simul...

It can be said that lubricants are used to reduce the friction between rubbing surfaces. This is done by separating the moving surfaces with a film of the lubricant, thereby replacing the friction of the metal to metal surfaces by the internal friction within the lubricant itself. Lubricants also act as a cooling agent to carry away heat generated by friction or conducted to the bearing surface...

For control applications aiming accurate positioning and path tracking friction modelling and compensation can be very important, especially when working with small displacements as usual in nano technologies. The paper at hand describes friction identification and friction model application for a linear high-precision ball bearing guide driven by a voice coil actuator and using high-resolution...

Abstract To improve the tribological performance of CSS-42L bearing steel, smooth surfaces (SSs), groove-textured (GSs), GSs with Sn-Ag-Cu (GSs-SAC), and Sn-Ag-Cu-Ti 3 C 2 (GSs-SACT) were prepared on CSS-42L. In addition, experimental studies conducted properties. The obtained results indicated that GSs-SACT exhibited best anti-friction noise reduction performances. These remarkable performance...