An updated single-piece roller path improves the ride and prevents rollers from coming loose.
Improvements to the lower assembly and the dipper extends the mean time between maintenance
Caterpillar recently showcased design enhancements for the lower works of its electric rope shovels that the company believes will reduce total cost of ownership and improve availability. The Cat 7495 and 7495 HF electric rope shovels feature multiple design upgrades that cover the track (crawler) frames, swing rack and rollers propel gearboxes, and rotating undercarriage.
Combined, Cat believes these design advancements can improve total cost of ownership up to 6% per operating hour and improve physical availability of the electric rope shovel up to 0.63%. All updates are found on current-year models and they can be retrofitted independently in the field.
A reengineered bolt-on design for track link sliders eliminates the need for casting welds. Miners using Cat rope shovels can benefit from up to a 22% cost-per-hour reduction with extended wear life and no maintenance. Integral wear indicators provide visual reference to help service technicians plan for slider maintenance.
Track frame life is enhanced with increased frame thickness, lowering stress in the plate for improved reliability. A new super bolt arrangement features shorter middle bolts, improving joint stiffness and maintaining preload. Access for cleanout has been improved with a three-hole track frame bell housing.
A single-piece swing rack casting eliminates previous vertical welds to improve durability.
Distributing shovel weight more evenly to the crawler side frame, the updated tapered shear ledge reduces end loading as the electric rope shovel pitches forward during digging. New lower side frame stiffeners maintain increased track clearance to the tracks, while improving rock protection.
Saving approximately 100 hours of field assembly time, the bolt-on motor base eliminates field welding and improves motor bolt access. Set screws simplify locating the base on the crawler and simplify motor alignment.
Solid Swing Rack
The swing rack absorbs the stress from every load. The 7495 and 7495 HF models now have a single-piece swing rack casting that eliminates previous vertical welds to improve electric rope shovel durability. The number of core holes have been reduced from 20 to four, positioned strategically in low-stress areas of the swing frame and located outboard to increase web strength. Improvements to the weld joint between the swing rack and car body further reduce stress.
An updated single-piece roller path increases roller life and eliminates seams to improve ride and prevent rollers from coming loose. Five symmetrical roller segments are now preassembled, improving alignment quality and installation efficiency. The upgraded thrust rail design improves access for inspection and retightening, while adding support to the thrust rail during operation.
A redesigned propel system eliminates the need to remove the propel transmission when servicing the drive tumbler and propel shaft, since they are now replaced from the outboard side of the machine. This significantly improves serviceability of the drive, decreases maintenance downtime by as much as 75% and lowers operating costs by as much as 10% versus the previous design. The component’s design updates extend rebuild life to up to 30,000 hours.
Improved dipper latching systems are increasing availability.
Sealed and continuously lubricated tapered roller bearings more evenly distribute thrust to improve propel durability. Fresh grease flows equally through both sets of bearings, eliminating potential contamination from bearing surfaces. Propel gearcase metallurgy has been optimized to improve toughness, while improved microgeometry enhances gear mesh to reduce contact wear.
Compatible with all electric rope shovels equipped with 79-in. (2,006-mm) track pads, a new track pad design improves structural support and steel chemistry. A proprietary heat treatment process increases hardness by 15% and toughness by 30% to improve roller path and drive lug wear.
The track pin design features improved alloy composition and higher toughness. A new track pin removal pocket for 7495 HF models offers an easy-to-use pin removal solution that features a weld-free integrated vertical surface to keep the cylinder stabilized during pin removal.
Dipper Tech Improves Uptime
Weir ESCO electric rope shovel dippers are equipped with low-friction latching systems. Some miners, according to the company, have reported as much as 70% reduction in unplanned downtime associated with latching system issues compared with the latching system provided by the original equipment manufacturer (OEM).
The rear-taper door’s short travel lowers truck impact during loading and softer closing for reduced dipper and snubber wear and tear. A 35% lower peak side-loading stress results in better reliability and longer service life, according to Weir ESCO. A recent customer comparison of an ESCO Production Master dipper to an OEM dipper resulted in a sustained 5.7% hourly production rate increase using the same shovel in similar conditions.
Weir ESCO also said that its tooth systems and wear protection, the Nemisys and WhislerPlus, systems, deliver longer life with fewer replacements and extended intervals between rebuilds. Using a proprietary lip alloy improves weldability and reduces likelihood of fatigue cracks to provide what Weir ESCO calls best-in-class lip technology.
L&H Sets New Standard for Undercarriages
A routine inspection on an L&H 495HF electric rope shovel undercarriage that was installed in early 2020 has shown that this assembly is projected to last approximately 40% longer than the competition. L&H Industrial said this is the new standard for its undercarriages. Using the L&H service program for inspections on this assembly provides mine operators with comprehensive recommendations for predictive maintenance and provides benefit in terms of annual planning.
