Answer Happy

Chapter 9 HOE PRODUCTION (Example 9.3) A crawler hoe having a 3-cy bucket is being considered for use on a project to excavate very hard clay from a borrow pit. The clay will be loaded into trucks having a loading height of 10 ft Soil-boring information indicates that below 10 ft. the material changes to an unacceptable silt material. What is the estimated production of the hoe in cubic yards bank measure, if the efficiency factor is equal to a 45 minute hour? Given Bucket-3cy (0) Material - hard clay Loading height - 10 ft Depth of excavation - 10 ft Efficiency factor - 45min per hour (E) E x 60-minhr to Hoe production 3600 secx QXF 1 x 1+%swell Q- heaped bucket capacity in Icy Fabucket fill factor for hoe buckets T = cycle time in seconds E = efficiency in minutes per hour Bucket fill factor (Table 9.4), hard clay ; use high__ (F) Typical cycle element times Optimum depth of cut is 30 to 60% of maximum digging depth. From Table 9.3 for a 3 cy size hoe, maximum digging depth is ft. Depth of excavation from above is 10 ft. _ft x 100 = _% 30% OK or not OK _ft x 100 = _%> 30% OK or not OK Therefore, under average conditions and for a 3-cy size hoe, cycle times from Table 9.5 would be: 1. Load bucket sec very hard clay 2. Swing with load sec load trucks 3. Dump load load trucks 4. Return swing Cycle time sec sec sec
Class of material, hard clay swell % (Table 4.4) 1600sec hr х сух. Probable production: sec/cycle min 1 X x 60 min (1+0.35) bcy/hr Check maximum loading height to ensure the hoe can service the trucks, from Table 9.3, to_ ft. - ft > 10 ft, OK or not OK