Document ID: chunk:federal_register_of_legislation:F2023C00958:reg:7:p12
Version: federal_register_of_legislation:F2023C00958
Segment Type: reg
Provision Reference: reg 7 (pt 12/16)
Character Range: 43862–46606

LEG2 vehicles
d = (W - L) sin (arctan (t / 2W))
         where:
          d is the horizontal distance from the centre of mass to the nearest roll axis
         t is the width of the wheel track of the front 'Axle'.
21.5.6.                          Height Location – Axle Lift Method
21.5.6.1.                    This test procedure requires the ability to accurately measure the height of elevation of the single-wheel axle, and accurately measure the 'Axle Load' (or axle weight) of the two-wheel axle (see paragraph 21.5.6.1.3. below). The test report shall take account of potential and known inaccuracies in measurement equipment, especially where the SSR nears the compliance limit.
21.5.6.1.1.              An inaccuracy of 5mm in the measurement of the height of elevation of the single-wheel axle results in an inaccuracy in the SSR of approximately 0.009 in the SSR range of interest (SSR between 1.0 and 1.5, an inaccuracy of 0.6% to 0.9%), whilst an inaccuracy of 1kg in the measurement of the weight over the two-wheel axle will result in an inaccuracy in the SSR of approximately 0.023 in the SSR range of interest (SSR between 1.0 and 1.5, an inaccuracy of 1.7% to 2.5%).
21.5.6.1.2.              These accuracy sensitivities should be considered in the context of the sensitivity of the stable pendulum test method at paragraph 21.5.4.
21.5.6.1.3.              Total mass is the same in the elevated position as in the normal position.
    F + R = Fe + Re = total mass
Where:
Re is the rear 'Axle Load' on the tyre(s) with the elevated vehicle in the 'Maximum Loaded Test Mass' condition; and
Fe is the front 'Axle Load' on the tyre(s) with the elevated vehicle in the 'Maximum Loaded Test Mass' condition.
Once the total mass is known at the 'Maximum Loaded Test Mass' condition (measured prior to elevation), it is only necessary to measure the two-wheel axle 'Axle Load' to determine the other 'Axle Load'.
21.5.6.2.                    Height Location for LEM1, LEP1 and LEG1 Category Vehicles (See Figures 3 and 6)
21.5.6.2.1.              The height of the CoM shall be determined as follows:
21.5.6.2.2.              With the suspension blocked to prevent movement and the vehicle in the 'Maximum Loaded Test Mass' condition, use blocks to elevate the front  to not less than 600 mm (Hfe), and determine the longitudinal location of the CoM in the elevated state (Le), from the centre line of the front 'Axle', using the formula:

Le = WeRe / (Fe + Re)

         Where:

    We is the wheelbase in the horizontal plane.
21.5.6.2.3.              The height of the CoM is given by the formula:

h = [(W - L) / tan θ – (We - Le) / sin θ] + r

         Where:

         Le is defined by the formula in 3.2.2 above;

         θ