The rear axle of a dual-axle lorry is loaded symmetrically to 6250kg. It has
two standard closely spaced twin wheel assemblies at its rear, with approximately
45mm between their walls in each case. The test commences with the loaded
wheels moved into the starting position (see Fig. 9.1). An initial reading is then
taken. The measurement cycle consists of the vehicle moving forward past the
front end or tip of the beam to a point where the wheels are a minimum of 3m
past the end of the tip. During this time the deflection of the beam is monitored
and the maximum value recorded. The deflection remaining at the end of the
test is the recovery deflection for that point. The readings are temperature corrected. Half the sum of the maximum deflection plus the recovery deflection
yields the deflection value, expressed in hundredths of millimetres.