Types of Loaders

1. Types of Loaders ©Dr. B. C. Paul 2000 Modified 2009 Note – These slides contain drawings copied from the book Surface Mining Equipment

2. Loading Equipment • Four Basic Types of Loaders • Cable Shovel • Hydraulic Front Shovel (also called hydraulic excavator) • Backhoe • Front End Loader

3. Front End Loader F is the Bucket - note that it is a solid unit. Dumping is achieved by rotation. Can be critical consideration in loading height G is Teeth - FELs known as whimpy diggers - load is spread over a bucket as wide as a machine - May have penetrating V

4. Digging Motion of FEL I, J, H, and E are the hinges and hydraulics used for rotating the bucket - They provide limited pry and dig motion C is a one piece arm moved by hydraulic cylinder D - Wide bucket - Rigid Arm - Limited Pry Pivot on bucket Limited Digger

5. Crowd Motion on an FEL Crowd Motion is the Tires. The machine drives forward - Powered by Diesel Engine A Oh Cool It has a Counter- Weight to help with Digging Force Problem of Tearing up Underfoot under wet conditions Hydraulics on arm competes with propel motion for power

6. The Articulated Machine Front End Loaders are articulated which gives them their Y shape loading pattern Mobility of FEL makes great for cleaning up spills

7. The Dilemma of Cab Position • Which side of the articulation point does the cab go on? • Put it in Front • Driver has better view of digging • He is in a better position to get squished if the pile collapses • Very bad backing view - this machine moves fast

8. The Other Choice • Put the Cab on the Back • Still a reasonable Dig view with less opportunity to get squished • Still rather marginal on backing view - some things are just dangerous • Vibration from motor causes operator fatigue • Now putting cabs on flotation suspensions

9. Hydraulic Front Shovel Has a two piece bottom dump bucket - Higher wear from two pieces - Bottom open eliminates need to pivot to dump - helps loading height - Can get a rock stuck too Hydraulic bucket opening for gentle loading - can position low over truck and open bucket at a controlled rate

10. The Machine That Digs It Machine has two piece are and a pivoting bucket - Allows range of motion like human arm - lots of dig and pry for hard rock Can Selectively Pick Out Rock Layers - Can be valuable for acid or toxic layers or prep. of synthetic topsoil Hydraulics can develop 100,000 psi at the teeth

11. The Machine That Swings This is a track mounted machine lacks mobility of FEL - Picks up load and pivots to dump into truck Tracks provide for low bearing pressure. Coupled with minimal movement is much easier on ground - especially when wet

12. View Arrangements Cab Location Provides Good View of Digging Operation Cab Location to one side can be a view problem for loading a truck on the wrong side Has a Low Built Upper Structure to allow open top access to components - with 5000 psi on hoses you need it

13. Other Machine Properties • Power Supply Can be Diesel or Electric (often Diesel) • Power is converted to hydraulic for most motions including propel • Hydraulics allow trade off between power and speed at steady engine speed • Very Gradable - Can Pull itself up with boom

14. The Backhoe

15. The Cable Shovel Basic Design has changed litte from the turn of the 1900s Spindly version shown here is stripping shovel. Was never popular outside Midwest and none built since 1969 - had more limited overburden range than dragline - operates on pit bottom so more vulnerable to water - had lower profit margin than draglines.

16. The Mining and Quarry Version Tall Massive Machine So Can Load Almost anything with no loading height problem Has Cables rather than hydraulics to drive motions - Can move in tension but gravity needed for other motions - dipper door is tripped and swings open under gravity Is a track and pivot machine like hydraulic excavator - big inertia and slower moving Has same operator cab view problem as HE Has a full field shop on back

17. Cable Digging Technique Has the limited swing up digging problem of the FEL Dipper (not called a bucket on this machine) does not pivot Cable connections avoid major shock transfers to boom - lets outlive the HE Crowd produced by either rack and pinion on boom or cable wheels - wheels preserve insulating boom from shock

18. Powering Cable Shovels • Except for Mike Muligan’s Steam Shovel all the big ones are electric • Extension Cord Does Limit Mobility (one reasons for machine shop on back) • New SCR and Frequency Control Systems offer good power control - even giant circuit boards • Simplicity makes high reliability

19. Comparative Advantages of Each

20. Loaders We Are Offered to Consider • The following loaders are also to be considered • Cat 994F with a 24.5 yard bucket • Cat 988BLog with a 38.66 yard bucket • Cat 5230B with a 22.5 yard bucket • Cat 5230ME with a 21 yard rock bucket • Cat 345B L series 2 with a 3.3 yard bucket • P+H 2300XPA with a 27 yard dipper • P+H 4100 with a 56 yard dipper

21. What Must a Good Loader Do? • It has to be able to handle the material without tipping over • It has to be able to get the load over the edge of the truck and preferably center and heap the truck • It has to be able to fill the truck in a reasonable integer number of passes • It has to be able to maneuver on the ground conditions and space available in the loading configuration

22. My Decisions • I propose to disqualify all front end loaders • Trucks at the bottom of the 3rd bench will get stuck so the FELs will almost surely get stuck also • FEL also has no chance of lifting high enough to load a truck on the top of a 30 foot bench. • Actually anything that loads from the bottom of the bench will be down in the mud • I’m going to suggest a Back Hoe