FI76429B - FOERFARANDE FOER ATT KONTROLLERA BROMSARNAS FOERENLIGHET HOS EN MOTORDRIVEN FORDONSKOMBINATION. - Google Patents

Description

! 76429

Method of checking the compatibility of the brakes of a motor vehicle combination

The invention relates to a method for checking the compatibility of the brakes of a motor-driven vehicle combination, which vehicle combination comprises a tractor or the like and a trailer or the like.

The compatibility of the brakes of a vehicle combination is currently checked by one of the following methods: 10 - theoretical fit - deceleration measurements by driving tests - dynamometer test

In the theoretical fit, the braking forces of the tractor and the trailer are calculated using the braking force tables prepared by the axle manufacturers 15. The results obtained shall be compared and the necessary coordination of the brakes of the vehicle combination shall be performed. This method of fitting is suitable for use in the manufacture of a combination and assists in component selection, but gives an inaccurate result in 20 devices already in use.

In deceleration measurements with driving tests, a fully loaded vehicle combination shall be braked 3 to 5 under the same conditions and at the same braking pressure and the maximum deceleration obtained shall be measured.

25 The same braking tests are performed separately on the tractor and the deceleration values obtained are compared.

The method is time-consuming and requires good weather and traffic conditions. The accuracy achieved depends on the deceleration measuring device used.

30 In the dynamometer test, the braking force of each axle of the vehicle combination at certain braking pressures is measured and the deceleration of the tractor and trailer is calculated separately from the results obtained. The results are compared to coordinate the brakes.

35 The method gives a fairly reliable picture if the combination is loaded to such an extent that sufficient displays are obtained for all axes. The slow rotation of the wheels impairs the reliability of the results.

The disadvantage of all current methods is that they require quite a lot of time for the results to be approximately reliable. Em. For these reasons, they cannot be used, for example, in connection with annual inspections or traffic control. The assessment of the compatibility of a tractor and a trailer is therefore most often left to faith.

By means of the method according to the invention, a considerable improvement in the above-mentioned drawbacks is obtained. The method according to the invention is characterized in that a force sensor and measuring and display devices placed between the coupling to be coupled to the tractor and the trailer measure the force on the traction devices during braking at a known braking pressure, from which the braking forces are determined separately for the tractor and the trailer. The force is preferably measured with a force sensor operating on the strain measurement principle.

An important advantage of the invention is its speed and reliability compared to known methods. The method makes it possible to check the compatibility of the brakes in connection with a normal inspection test run and, for example, in traffic control situations. The result is absolutely reliable and is obtained with a few brakes, and does not require special loading conditions or other aids. The necessary adjustment measures can be performed by comparing the specified braking forces with the required values.

The invention will now be described in more detail in the form of an exemplary embodiment with reference to the drawing, in which Figure 1 shows the general arrangement of the apparatus for carrying out the method in a vehicle combination and Figure 2 shows the apparatus schematically.

According to Figure 1, the trailer 20 is coupled to the traction vehicle 35 by means of a force sensor 11 and a connecting piece 12. The connecting piece 12 is shaped so as to allow only longitudinal movement.

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The force sensor 12 is connected by a cable 14 to measuring and display devices 16, which are placed in the cab of the tractor 10. The braking pressure of the trailer 20 is transmitted from the control pressure regulator 13 via the control pressure line 15 to the measuring and display devices 16, from which the braking pressure can be read from the pressure gauge 18 (Fig. 2).

According to Figure 2, the difference in braking force between the tractor and the trailer acting on the force sensor 11 is transmitted via a cable 14 to a display device 17, which may be of the meter or plotter type, for example. If the trailer pulls during braking, ie the brakes are oversized, the display device gives, for example, a display with a minus (-) sign and, in the case of pushing, a display with a plus (+) sign.

With the same equipment, in addition to the above-mentioned li-15, for example, the traction capacity of a tractor can be measured by braking only the trailer. In addition, the tensile strengths of different trailers can be measured with different tires and tire pressures.

Claims (2)

4 76429 A method for checking the compatibility of brakes of a motor vehicle combination, which vehicle combination comprises a tractor (10) or the like and a trailer (20) or the like, characterized in that a force placed between the coupling (12) and the trailer (20) connected to the tractor (10) The sensor (11) and the measuring and indicating devices (16) measure the force applied to the traction devices during braking at a known braking pressure 10, on the basis of which the braking forces are determined separately for the tractor and the trailer. Method according to Claim 1, characterized in that the force is measured by means of a force sensor (11) operating on the principle of strain measurement.