Measuring and testing – Dynamometers – Responsive to force
Patent
1982-11-22
1984-12-18
Ruehl, Charles A.
Measuring and testing
Dynamometers
Responsive to force
73 65, 73849, G01L 506, G01N 320
Patent
active
044884443
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a testing device for tennis racquets to measure the tension of the stringing. The degree of tightness or stiffness of the strings of the hitting surface of a tennis racquet is subject to variation. The higher the tension or tightness of the strings, the stiffer the hitting surface. The stringing may be made from single stretched synthetic gut strings or from twisted multi-filament strings. Natural gut may be used instead of synthetic gut. Synthetic strings have a higher wear resistance. A stringing of synthetic gut reacts tight at hard strokes and soft at soft strokes.
The particular nature of the stringing is of critical importance. Depending on the player's handling of the racquet, the ball is bounced off the stringing and returned at varying speeds and spin. During this brief encounter lasting no longer than a few thousandths of a second, ball, stringing and racquet are temporarily deformed. Of the racquet, it is particularly the frame that is subjected to deformation. All these factors taken together, hardness of the ball, stiffness of the stringing, flexibility of the frame and handling of the racquet, determine the degree of ball control.
A tournament player usually possesses several racquets and uses his judgment as to which racquet is best suited for a match with a particullar opponent, the type of ball used and the condition of the court. Instead of estimating the tension of the stringing empirically, the advanced player will find it of advantage to be able to measure the tightness of the stringing accurately.
STATE OF THE ART
Several devices are known to measure the tension of racquet stringings. In one device, the stringmeter is attached to the frame itself and the tension of the stringing is measured by a weight loaded beam. This type of measurement has the disadvantage that the measuring result is not just a straight indication of the tension of the stringing, but it also includes the flexibility value of the frame.
OBJECT OF THE INVENTION
It is the object of the present invention to create a measuring device by which the prior disadvantage is overcome, so that the measuring result is a true indication of the tension of the strings, without also taking into account the stiffness of flexibility, resp. of the frame. Since the stiffness of the frame is of importance by itself, however, it is another object of the invention to measure the frame stiffness both in the strung and the unstrung condition of the racquet. Finally, a further object of the invention is to use the device for determining the balance point of the racquet.
THE INVENTION
The device according to the invention comprises a base plate with two detachable lateral supporting bars adjustable to accommodate and center the frame of a tennis racquet to be tested, a bracket block connected to the base plate and supporting a weight loaded beam pivotably mounted therein, the beam being provided with a plunger head directed onto the center of a strung frame to be tested, and a gauge attached to the bearing block with the plunger of the gauge resting on the beam.
For the purpose of measuring also the stiffness of the frame, be it strung or unstrung, it is of advantage that a supporting bar is detachably provided in the mid area of the base plate and transversely to its longitudinal direction, and that a counterbracket for the grip of a racquet to be tested is provided at the end of the base plate opposite the bracket block.
THE DRAWINGS
The drawings illustrate by way of example an embodiment of the device of the invention, which will be further described with reference to the drawings, in which:
FIG. 1 is a side view of the testing device of the invention during measurement of the tension of the stringing.
FIG. 2 is a top plan view of the device of FIG. 1.
FIG. 3 shows the device of FIG. 1 in a modified condition for measuring the stiffness of the frame.
FIG. 4 shows the device of FIG. 1 in a view from below; and
FIG. 5 shows the device of FIG. 1 as used for locating the balance point of a tennis racquet.
REFERENCES:
patent: 2299722 (1942-10-01), Burns et al.
Weber Hans R.
Weidmann Ulrich
Ruehl Charles A.
Speckman Thomas W.
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