ISO 7096:2000 pdf download – Earth-moving machinery -Laboratory evaluation of operator seat vibration
ISO 7096:2000 pdf download – Earth-moving machinery -Laboratory evaluation of operator seat vibration.
A platfom the dimensions of which correspond approxmately to those of the operators platform of an earth- moving machine, shall be mounted on a vibrator which is capable ot generating vibration along the verbcal axis (see Figure 1).
NOTE In the case 01 classes EM 1 and EM 2 the vibrator shoid be capable of simulating sinusoidal vibration having a displacement amplitude of at least t 7,5cm at a frequency of 2 Hz; see 5.41
5.2 Test seat
The operator seat br the test shall be representative ot series-produced models, with regard to construction, static and vibration characteristics and other features which may affect the vibration test result. Before the test, the suspension seats shall be run-in under conditions stipulated by the manufacturer. It the manufacturer does not state such conditions, then the seat shall be run-in for 5 000 cycles, with measurements at 1 000 cycle intervals.
For this purpose, the seal shall be loaded with an inert mass of 75 kg and adiusted to the mass in accordance with the manufacturers instructions. The seat and suspension shall be mounted on the platform of a vibrator, and a sinusoidal irut vibration shaM be applied to the platform at approximately the suspension natural frequency. This input vibration shall have a peak to peak displacement suftient to cause movement of the seat suspension over approxImately 75 % of its stroke. A platform peak to peak displacement of approximately 40% of the seat suspension stroke Is lPeIy to achieve this. Care should be taken to ensure against overheating of the suspension damper during the running-In, for which forced cooling Is acceptable.
The seat shall be considered to have been run-in it the value for the vertical transmissibility remawis within a tolerance of ± 5 $ when three successive measurements are performed under the condition described above. The time interval between two measurements shall be halt an hour, or 1 000 cycles (whichever is less), with the seat being constantly wn-in,
The seat shall be adjusted to the weignt of the test person In accordance with the manufacturers instructions.
With seats where the suspension stroke available is unaffected by the adjustment for seat height or test person weight, testing shall be performed with the seat adusted to the centre of the stroke.
With seats where the suspension stroke available is affected by the adjustment of the seal height or by test person woight, testing shall be performed in the lowest position which provides the full working suspension stroke as specified by the seat manufacturer.
When the inclination of the backrest is adjustable, it shall be set approximately upright, inclined slightly backwards (approximately 10° 50)
5.3 Test person and posture
The simulated input vibration test shall be performed with two persons. The light person shall have a total mass of 52kg to 55 kg. of which not more than 5 kg may be carried in a belt around the waist. The heavy person shall have a total mass of 98 kg to 103 kg. of which not more than 8 kg may be carried in a belt around the waist.
Each person shall adopt a natural upright position on the seat and maintain this position throughout the test (see Figure 1).
Differences en the posture of the test person can cause a 10% difference between test results. For this reason, recommended angles of knees and ankles have been specified In Figure 1.
5.4 Input v(bratlon
5.4.1 Simulated Input vibration test to evaluate the SEAT factor
This International Standard specifies the Input vibration In nine Input spectral classes (EM I through EM 9) for earth-moving machinery for the purpose of determining the SEAT factor.
The vibration characteristics for each input spectral class EM 1 through EM 9 are shown in Figures 2 through 10,respectively.Equations for the acceleration power spectral density curves of Figures 2 to 10 are included inTable 2.The curves defined by these equations are the target values to be produced at the base of the seat for thesimullated input vibration test of 5.5.2.