Capacity spoon required for a job depends on the requirement of output per hour, the density of the material, the charge for a particular type of material, called “fill factor” and cycle time. The hourly production requirement is set by project management. The number of tons of material per square yard is obtained from standard reference tables. The cycle time is the time between filling a spoon and when it is back-filled. The type of material is crucial because it determines the weight per square yard and the fill factor varies by manufacturer saucepan.
Read the excavation project specifications to determine the nature of the material to move. Determines the weight of the material with a table of standard reference, as the table “Weights of building materials, agricultural products and soil loads for buildings” of the University of Penn State or the “Reference Book estimator buildings.” If the material is moving gravel, the reference book estimator buildings says the gravel weighs 2,500 pounds (1.25 tons) per square yard. If the material is gravel, search for “gravel” in the data sheet filling factor provided with the hub. Specify the fill factor, as a range, how much to complete the capacity of the bucket with the material. If the spoon should not be filled to more than 85 percent of its capacity with gravel, that is the filling factor for that material.
Take the time an operation with a stopwatch. Starts when the spoon begins to “dig” and stops counting when digging back again. Divide 60 by the cycle time for the number of cycles per hour. If the cycle time is 0.5 minutes, 60 / 0.5 = 120 cycles per hour.
Divide the requirement of hourly output per hour cycles with your calculator. If administration requires 800 tons per hour, and the machine and the operator moving averaging 120 cycles per hour, then 800/120 = 6.67 tons per cycle move.
Divide the load per cycle (6.67 tons) by the density of the material (1.25 tons / square yard) to determine the nominal bucket capacity: 6.67 / 1.25 = 5.28 square yards.
Divide the rated capacity of the spoon fill factor to find the required capacity of the spoon: 5.28 / 0.85 = 6.21 square yards.