Nico van Loey explains how an intelligent coupling solution is proving popular for longwall mining applications
Circumstances in longwall mines are harsh on miners and equipment alike. The mining process involves roof shields operating at working pressures of 350 bar, putting 81KNm of force against the fitting of the hydraulic connection. Factoring in pressure spikes from pumping equipment, impulses from self-advancing shields and corrosion, the component conditions are extremely tough.
Traditional staple-lock couplings become deformed and corroded, making it challenging to replace damaged hose assemblies or to disconnect roof shields. This often results in workers mistreating equipment, leading to numerous incidents and triggering the need for extreme caution. Gates designed its iLok coupling to improve safety as well as productivity and exclude the inherent limits of the staple-lock design.
The iLok is simple to understand as well as to use. To connect the fitting, the male nut is hand-tightened onto the female, drawing the sealing surface under the seal in the female and protecting it from potential damage. A secure cable distributes forces along the full length of the flange area, preventing uneven staple stress or deformation. When disconnecting, the cable is cut, removed and the nut can be loosened by hand. The back of the swivel nut has slots, so a spanner wrench can be used in case an extra tool is needed to loosen the coupling.
Faster and safer longwall moves
The ease of connection and disconnection is key for improving both safety and productivity. Gates states that the average disconnect time per coupling can be reduced by up to 90% compared to the staple-lock. This means that iLok can potentially save hundreds of man-hours on every longwall move. If the cable lock is removed while the line is still under pressure, the nut will continue to hold the fitting together, dissipating the pressure away from the worker’s face. Unlike a staple lock, the iLok uses a nut that contacts the entire flange surface, helping to distribute forces evenly and prevent the flange from deforming. No tools are needed to engage or disengage the coupling, so workers will not be tempted to use hammers or chisels.
To further increase the lifetime of iLok assemblies in the highly corrosive mining environment, they are plated with Gates TuffCoat Xtreme. This coating goes beyond ISO 9227 standard requirements, offering 840 hours of red rust protection. The coupling has not only been tested at 420 bar pressure for 300,000 impulse cycles (as applicable in mining ratings for static applications), it has also been tested to one million impulse cycles at 133% of 350 bar working pressure for hydraulic application standards. The connectors can be used on original equipment, as well as in replacement projects, using the appropriate iLok adapter to connect to staple-lock or flange.
Several important mining companies, including Wyoming’s Bridger Coal and Bowie Resources, have switched over to iLok couplings. The key drivers for these companies to make the change are the new solution’s simplicity, ease of use, improved safety, and the time and labour savings in disconnecting and reconnecting.
Nico van Loey is product manager, Hydraulic Hose, Couplings & Equipment at Gates Europe.