Excavators & Crane Shovels Hydraulic Excavators –Faster cycle time than shovels –Higher bucket penetrating force –More precise digging –Easier operator control –Attachments – pg 41 - 43
Excavators & Crane Shovels Parts – Figure 3-2 –Carrier or mounting Track –Excellent on-site mobility – will go anywhere –Low ground pressure – good for low trafficablity soils truck & wheel mountings –Greater mobility between job sites – faster –Require better surfaces to work on –Revolving superstructure containing power and control units –Front end assembly
Production Need to know volume of material in one bucket load Figure 3-1 –Plate line capacity – volume contained in outline of bucket –Struck capacity – volume when mat’l is struck off even w/ sides of bucket –Water line capacity – assumes material only to lowest edge of bucket –Heaped capacity – max volume that can be placed in bucket without spillage
Production Ratings usually based on struck volume –Assumption is made that since bucket is usually heaped that a 5 cy bucket will pick up 5 cy of bank not loose –Better to use bucket fill factors – Table 3-2
Operation & Employment Excavators Fig 3-3 & 3-4 Trenching work Production estimating Production (LCY/hr) = CxSxVxBxE C – cycles/hr S – swing depth factor T 3-4 V – heaped bucket volume B – bucket fill factor E – job efficiency Trenching work may also require a fall in factor for dirt going back in the trench T 3-5
Shovels –Larger than excavators –Good for excavating above track line –Digs using Breakout force and crowding force –Can form its own roadway –Can shape sides of cut and dress slopes –Should have a vertical face to dig against –Production is found same way
Trenching Technology Good for digging a narrow trench with the spoil going to the side of the trench Chain trenchers, ladder trenchers, bucket wheel trenchers
Your consent to our cookies if you continue to use this website.