Document ID: chunk:federal_register_of_legislation:F2012C00535:front:0:p17
Version: federal_register_of_legislation:F2012C00535
Segment Type: other
Provision Reference: 
Character Range: 48204–51143

degree of accuracy.

       1.5.              The centre of gravity position of the unladen vehicle (unladen kerb mass Mk) shall be determined by measurements.

       1.6.              The centre of gravity position of the vehicle with total effective mass (Mt) may be determined:

       1.6.1.              by measuring the vehicle in total effective mass condition, or

       1.6.2.              by using the measured centre of gravity position in the unladen kerb mass condition and considering the effect of the total occupant mass.

       1.6.3.              In the case of a double deck vehicle, the mass of the passengers both on the lower and upper deck seats shall be taken into account.

2.              Measurements

       2.1.              The position of the vehicle's centre of gravity shall be determined in the unladen kerb mass condition or the total effective vehicle mass condition as defined in paragraphs 1.5. and 1.6.  For the determination of the position of the centre of gravity in the total effective vehicle mass condition, the individual occupant mass (factored by the constant, k = 0.5) shall be positioned and rigidly held 100 mm above and 100 mm forward of the R point (which is defined in Regulation No. 21, annex 5) of the seat.

       2.2.              The longitudinal (l1) and transverse (t) coordinates of centre of gravity shall be determined on a common horizontal ground (see Figure A3.1) where each wheel or twinned wheel of the vehicle is standing on an individual load cell.  Each steered wheel shall be set to its straight-ahead position.

       2.3.              The individual load-cell readings shall be noted simultaneously and shall be used to calculate the total vehicle mass and centre of gravity position.

       2.4.              The longitudinal position of the centre of gravity relative to the centre of the contact point of the front wheels (see Figure A3.1) is given by,

where:

      P1  =  reaction load on the load cell under the left-hand wheel of the first axle
        P2  =  reaction load on the load cell under the right-hand wheel of the first axle
        P3  =  reaction load on the load cell under the left-hand wheel(s) of the second axle
        P4  =  reaction load on the load cell under the right-hand wheel(s) of the second axle
        P5   =  reaction load on the load cell under the left-hand wheel(s) of the third axle
        P6   =  reaction load on the load cell under the right-hand wheel(s) of the third axle
        Ptotal  =  (P1+P2+P3+P4+P5+P6)  =  Mk  unladen kerb mass; or,
                                                         =  Mt    total effective vehicle mass, as appropriate
        L1  =  the distance from centre of wheel on 1st axle to centre of wheel on second axle
        L2  =  the distance from centre of wheel on 1st axle to centre of wheel on third axle, if
                  fitted

Figure A3.1 - Longitudinal position