CASE STUDY-REXROTH
The reliability of the Rexroth AA11VLO pumps is especially critical in deep drilling applications requiring high pressure capacity and pullback force delivered by the drill rig .
T130XD was designed for drilling applications such as shallow oil and gas , deep water wells , geothermal exploration and ... deep mine rescue .
A key component of the hydraulic system that powers the Schramm drill are the Rexroth AA11VLO variable displacement axial piston pumps , supplied by local Rexroth distributor Airline Hydraulics , Inc . ( Bensalem , PA ). Schramm selected the Rexroth AA11VLO130 pumps when designing the T130XD because of their proven performance , particularly in deep drilling applications requiring the high pressure capacity and pullback force delivered by the rig .
Rexroth ’ s AA11VLO series of axial piston variable displacements pumps are designed for hydrostatic drives in open circuits . They offer high power capacity and displacement in a compact design , with nominal pressure of 5100 psi ( 350 bar ) and maximum pressure of 5800 psi ( 400 bar .) The AA11VLO130 is equipped with a charge pump enabling high input speeds , which is especially important at high-altitude operation , like Chile . Its 130 cc / rev ( 7.93 in 3 / rev ) can operate at engine speeds up to 2,500 rpm .
When the Chilean government sent out the call across the country for assistance , it was determined that the T130XD rig offered several potential advantages for the rescue :
• The T130XD is well-suited for drilling with reverse-circulation down-the-hole hammers , making it especially ideal for drilling through the Chilean granite .
• Schramm ’ s rig was designed to drill off a vertical axis , enabling it to utilize one of the existing pilot holes to drill a rescue portal , and would not have to be emplaced directly above the miners .
• The T130XD in Chile was equipped with Schramm ’ s highest capacity top head , capable of drilling holes up to 28 inches in diameter .
• The T130XD is designed for fast teardowns and relocations , enabling it to make the 1,000 km trip in relatively short time .
Given the advantages offered by the T130XD , the Chilean mining authorities developed a “ Plan B ” rescue plan : the T130XD would enlarge one of the 5.5-inch diameter initial probe holes , drilled with two passes . The first pass would increase its diameter to 12 inches and the second pass to 28 inches diameter , to allow a rescue rig to be lowered .
Putting Plan B into action Arriving at the San Jose mine on September 30 , the T130XD was quickly set up and drilling on the
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| Global MDA Journal | NOV-DEC 2017
Schramm ’ s drill uses four Rexroth AA11VLO130 pumps , which supply hydraulic pressure to the top mast head and mast cylinders . The top mast head is the mechanism at the top of the drill mast that provides the pullback force to manipulate thousands of feet of pipe down the hole ; the mast cylinders support this function .
Photo courtesy of Schramm , Inc .
The variable displacement pumps on the T130XD supply hydraulic pressure to the top mast head for manipulating thousands of feet of pipe . www . ghmediabusiness . com