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The Fourier spectral estimates of machined surface roughness data are investigated in detail, and, in particular, the shape of these estimates is examined. From these assessments, a parameter is derived which enables a description to be produced of the underlying form of spectral estimates of machined surface roughness data, without the requirement for a stylus instrument operator to select a standard cut-off filter.

The orthogonal transforms most commonly used in engineering applications are compared in their ability to characterize surface texture data. The results suggest that, for this application, the Fourier and cosine transforms are to be preferred because of their ability to model the data more precisely and because of their relatively rapid rates of convergence.

The spectral analysis of surface texture data is extended so as to include the longer wavelength ‘waviness’ features in addition to the ‘roughness’ aspects. This results in the identification of an underlying form in the spectral estimates of engineering surfaces whose complete description requires only two parameters. Also, by showing that the spectral estimates converge to a final steady value at the longer wavelengths, the need to select and apply a standard cut-off filter is avoided.

This paper gives a linear analysis for the steady motion of a flexible two-axle railway truck on curved track. Most existing truck designs are too rigid to be self-steering, but provided that the primary suspension is sufficiently flexible, it is shown that a truck can negotiate main line curves without slipping or flange contact. Results are obtained for the maximum rolling displacement of the wheelsets (the tracking error), Fig. 8, and the minimum radius of curvature for no slipping, Fig. 10, expressed as a function of the suspension stiffness. It is shown that lateral loads due to superelevation deficiency have only a small effect on the motion of the truck, which is mainly determined by creep forces arising from the geometric inability of the four wheels to roll freely on curved track.

Centrifugal pendulums have been used for many years to limit the torsional vibration of reciprocating engines. Recently small pendulums, designed to swing through amplitudes of about 45 deg, have been tested for lightweight aircraft engines. These have not functioned properly, and have been found to swing through much larger angles than expected, damaging the stops limiting motion of the pendulum counterweight. This paper investigates the large-amplitude motion of centrifugal-pendulum vibration absorbers.