Measuring and testing – Frictional resistance – coefficient or characteristics
Patent
1988-08-18
1990-01-02
Noland, Tom
Measuring and testing
Frictional resistance, coefficient or characteristics
G01N 1902
Patent
active
048904775
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to ski maintenance gear, and more specifically to a device for testing the ski sliding surface.
BACKGROUND OF THE INVENTION
Nowadays in modern skiing success of a skier specializing in cross-country skiing, biathlon, alpine skiing, ski jumping and Nordic combination depends not only on his physical fitness, morale and skill, but also on the proper choice of skis or the type of ski sliding surface made of different materials with or without grooves of different materials with or without grooves of different shape and width, as well as the type of wax applied to the ski sliding surface.
In view of varying snow properties (e.g., due temperature and humidity changes) determining the ski sliding surface friction against the snow, proper selection of the sliding surface type and wax necessitates accurate and timely (on the day of competition) measurements of sliding properties (dynamic friction) and track-holding properties (static friction) of different types of ski sliding surface and ski waxes.
The majority of skiers choose skis and ski wax experimentally by means of multiple testing of a limited number of various ski sliding surfaces and waxes. It is a time-and effort-consuming procedure which, nevertheless, does not yield sufficiently accurate results. That is why when choosing skis, type of their sliding surface and wax sportsmen and coaches rely mostly on personal experience and intuition.
Prior art devices for testing the ski sliding surface smeared with wax or without it due to their structural features do not provide for accurate and timely selection of a desirable type of skis, ski sliding surfaces and waxes.
There is a prior art device for ski wax selection (URSS Inventor's Certificate No. 188340. Int.Cl. A63C 11/04, published in the official bulletin "Otkrytiya, Izobreteniya, Promyshlennye Obraztsy, Tovarnye Znaki", 1966, v. 21) comprising a mock-up ski with ski wax applied to its sliding surface and a percussion mechanism for propelling the mock-up ski on the snow designed as a spring-loaded pusher. The device is intended to determine the sliding properties of different waxes on the basis of measuring the mock-up ski sliding distance when it comes forward.
This device is rather slow in operation as it takes quite a long time to propel the mock-up ski, measure the sliding distance and return the mock-up ski to the initial position. Such a device shows low accuracy of sliding properties measurement due to substantial influence of static friction (with speed approaching zero) and roughness of the snow on which measurements are conducted and also limited functional abilities as the ski wax choice is based only on sliding properties measurement.
A prior art device for testing the ski sliding surface (cf. USSR Inventor's Certificate No. 787051, Int.Cl. A63C 11/04, published in the official bulletin "Otkrytiya, Isobreteniya, Promyshlennye Obraztsy, Tovarnye Znaki", 1980, v. 46) comprises a case housing accommodating a spiral spring one end of which is attached to the case and the other--to an axle, a support bushing an exterior end of which holds a disk whose end face intended for interaction with snow or imitation surface is made of a material forming the test ski sliding surface, and a mechanism for measuring relative rotation of the disk and the case.
The mechanism for measuring relative rotation of the disk and the case contains a limb with a scale and a knob, and also an overrunning clutch for recording the relative rotation value defining snow or imitation surface holding capacity of the test ski sliding surface with ski wax applied to it.
After the device has been set up on the snow the knob of the limb is turned. The spiral spring connected with the limb and the support bushing starts winding up thus giving rise to a growing torque on the support bushing. Winding continues until the torque exceeds the moment of resistance created by the snow-holding force of the test ski sliding surface. The disk together with the support bushing rotates in
REFERENCES:
patent: 3791489 (1974-02-01), Vernazza et al.
patent: 3975940 (1976-08-01), Brungraber
patent: 4798080 (1989-01-01), Brungraber
Kamenskikh Vasily A.
Kharin Boris N.
Losev German P.
Vaisberg Pavel M.
Noland Tom
Simons Michele
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