For the AAES studies, researchers needed to calculate on paper the required values for machine parameters, such as ground speed, conveyor speed, and gate height, to achieve target application rates. They developed a method for performing the calculations based on the theoretical volumetric flow rate of material exiting the hopper and being spread by the spinners. Several measurements are required for the paper calibration method. These include ground and conveyor speeds, gate height and width, and density of the litter. The ground speed can be determined by timing the spreader as it drives a certain distance.
Conveyor speed can be more difficult to check.
However, by determining the pitch size of the conveyor chain and the number of teeth on the conveyor sprocket, operators can calculate conveyor speed from the rotational speed of the shaft on which the sprocket is mounted. Pitch size is the distance from the roller center of one chain link to the roller center of the next. The density of the litter can be determined by loosely filling a container of known volume with litter and determining the weight of that litter. If the actual density cannot be measured, an estimated value of 30 pounds per cubic foot can be used. The relationships used for calibration calculations can be determined based on what is happening during the spreading operation.