In some cases the frequency of the whirl coincides with and " locks on to " the critical speed of the machine shaft; this condition is known as " oil whip ".
42.
Before the derailment, there was no requirement for the co-driver to call out critical speed limit changes, nor prohibit the co-driver from leaving the cab to, say, prepare beverages in the adjacent area.
43.
A real railway vehicle has many more degrees of freedom and, consequently, may have more than one critical speed; it is by no means certain that the lowest is dictated by the wheelset motion.
44.
Many practical applications suggest as good practice that the maximum operating speed should not exceed 75 % of the critical speed; however, there are cases that require speeds above the critical speed to work correctly.
45.
Many practical applications suggest as good practice that the maximum operating speed should not exceed 75 % of the critical speed; however, there are cases that require speeds above the critical speed to work correctly.
46.
This expression yields a significant overestimate of the critical speed, but it does illustrate the physical reason why hunting occurs, i . e . the inertial forces become comparable with the adhesion forces above a certain speed.
47.
If Lorentz symmetry can cease to be a fundamental symmetry at Planck scale or at some other fundamental scale, it is conceivable that particles with a critical speed different from the speed of light be the ultimate constituents of matter.
48.
This star is rotating at about 92 % of its critical speed, completing a full rotation every 1.12 days . This is giving the star an oblate spheroid shape with an equatorial bulge that is 24 % larger than the polar radius.
49.
In practice, below the critical speed, the lag between the two motions is less than a quarter cycle so that the motion is damped out but, above the critical speed, the lag is greater than a quarter cycle so that the motion is amplified.
50.
In practice, below the critical speed, the lag between the two motions is less than a quarter cycle so that the motion is damped out but, above the critical speed, the lag is greater than a quarter cycle so that the motion is amplified.
