Document ID: chunk:federal_register_of_legislation:F2023C00958:reg:7:p11
Version: federal_register_of_legislation:F2023C00958
Segment Type: reg
Provision Reference: reg 7 (pt 11/16)
Character Range: 41234–44077

the centre line of the front 'Axle', is determined from the formula
L = WR/(F + R)
         where:
         W is the wheelbase
              R is the rear 'Axle Load' on the tyre(s) with the vehicle in the 'Maximum Loaded Test Mass' condition
              F is the front 'Axle Load' on the tyre(s) with the vehicle in the 'Maximum Loaded Test Mass' condition
21.5.4.                          Height Location – Stable Pendulum Method (See Figure 3)
21.5.4.1.                    For LEM1, LEP1 & LEG1 vehicles - with the vehicle standing on a level surface, mark a horizontal line parallel to the vehicle longitudinal centreline, passing through the centre of the vehicle rear 'Axle' - this is the reference line.
21.5.4.2.                    For LEM2, LEP2 & LEG2 vehicles - with the vehicle standing on a level surface, mark a horizontal line parallel to the vehicle longitudinal centreline, passing through the centre of the vehicle front 'Axle' - this is the reference line.
21.5.4.3.                    For LEM1, LEP1 & LEG1 vehicles chock both rear wheels.
21.5.4.4.                    For LEM2, LEP2 & LEG2 vehicles chock both front wheels.
21.5.4.5.                    For LEM1, LEP1 & LEG1 vehicles raise the front of the vehicle until the centre of mass is directly over the rear 'Axle'.
21.5.4.6.                    For LEM2, LEP2 & LEG2 vehicles raise the rear of the vehicle until the centre of mass is directly over the front 'Axle'.
21.5.4.7.                    Measure the angle between the reference line and the horizontal (See Figure 5).  An inaccuracy of 0.1 degrees measured inclination results in an inaccuracy in the SSR of approximately 0.0025 in the SSR range of interest (SSR between 1.0 and 1.5, an inaccuracy of 0.16% to 0.25%).
21.5.4.8.                    The height of the centre of mass is given by the formula:
21.5.4.8.1.              For LEM1, LEP1 & LEG1 vehicles
h = r +((W - L) / tan  )
         where:
         r is the rolling radius of the tyre fitted to the wheel
21.5.4.8.2.              For LEM2, LEP2 & LEG2 vehicles
h = r +(L / tan  )
         where:
         r is the rolling radius of the tyre fitted to the wheel
21.5.5.                          The horizontal distance from the centre of mass to the nearest roll axis (dimension "d") is calculated from the formula shown below:
21.5.5.1.                    For LEM1, LEP1 & LEG1 vehicles
d = 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 rear 'Axle'.
21.5.5.2.                    For LEM2, LEP2 & 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'.