ahv = ahwx2+ ahwy2+ ahwz2_ah_ahv_ahThe new Machinery Directive requires vibration total values. A vibration total value is based on a vibration measurement in three directions, x, y and z.The vibration total value (ahv) is the vector sum of the three different directions (ahwx, ahwy & ahwz) at one transducer position. See the equation (1).Three different operators carry out three series of five consecutive measurements on each model, using three different units. Vibration measurement are made in two positions when the tool has mass of 2 kg or over (see figure 2) or when the tool has a support handle (see figure 3). For each hand position, we combine the result from the three operators into one value (ah), using the arithmetic mean of the three values. values for each hand position are calculated as the arithmetic mean of the ah values for the different tools on that hand position. The declared value, ahd, is the highest of the values reported for the two hand positions. The uncertainty K value is estimated by the equation (2).Oil-pulse tools with a mass less than 2kg are normally operated using only one hand and therefore only the hand position on the trigger handle is measured. Tools of a mass of 2kg or more are normally operated using both hands and measurements are made in two positions. For tools without a side handle, the second hand position is on the front casing or – if that is not possible – on the motor housing (see figure 2). For tools with a side handle, vibrations are measured in three directions both on the trigger and the support handle (see figure 3). On the tools intended to be used with two hands, two positions are measured and the position with the higher value is declared.K = 1.5σtFigure 2 : without Support HandleEquation (1) *See 6 Characterization of vibration, 6.4 Combination of vibration directions.Equation (2) *See Annex B Determination of uncertainty, B.3 Tests on three machines.Figure 3: with Support HandlePOWER TOOLS GENERAL CATALOGEx. Measurement Locations for Pistol Grip Type Oil-Pulse Tools2) DeclarationWe declare vibration total values (Ahd) and measurement uncertainty (K). Vibration total values are to be given as numbers when they are 2.5m/s2 or over. For tools with vibration total values lower than 2.5m/s2, we state < 2.5m/s2. Measurement uncertainty K values are given as numbers.88Vibration Values1) MeasurementVibration is measured according to the relevant part of ISO 28927 series. For some tools that are not covered by ISO 28927 series, ISO 20643 is used to develop a suitable test procedure.
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