SOCIETY OFAUTOMOTIVE ENGINEERS, INC. TwoPennsylvania Plaza, NewYork, N.Y.10001 Progress inthe ArtofCoal Hauling Jackson Medley Kress Corp. National Combined Farm, Construction &Industrial Machinery andPowerplant Meetings Milwaukee, Wis. September 11-14, 1972720797 Downloaded from SAE International by University of New South Wales, Monday, August 27, 2018©SOCIETY OFAUTOMOTIVE ENGINEERS, INC., 1972 Downloaded from SAE International by University of New South Wales, Monday, August 27, 2018720797 Progress inthe ArtofCoal Hauling Jackson Medley Kress Corp. OFTHE PROVEN ENERGY RESERVES oftheUnited States, 88% iscoal, according toarecent publication ofthe American GasAssociation. Fig. 1shows thelocation ofthese deposits. Sixhundred million tonsofcoalwere mined inthe United States in1970, andofthat quantity,54%(I)*went totheutility industry. Inspite ofthepresent ecology spat andthegrowth ofnuclear powerplants, thepredictions ofthe Federal Power Commission (2)* isthatby1990 theutilities alone willbedemanding 700million tonsofcoal. The estimates ofCoal Age(2)arethat abillion tons willbe mined peryearby1990. Ofthisquantity itcanbeprojected thatstrip mining willaccount forover500million tons (Fig. 2) or approximately 2-1/2 times theamount mined to day. Theactual rateofgrowth forthecoalindustry willdepend greatly upon theproduction costofcoal, anditis thisfactor which hasstrongly encouraged Kress Corp. to concentrate their efforts onimproving thestate-of-the-art in strip mine haulage trucks. Itisherethat webelieve the economies ofscale andimproved efficiency influence the purchasing decisions ofthestrip mine operators asthey gear upforthepredicted increase inproduction demands. EXISTING COAL HAULER DESIGN Present haulage units may bedivided intotwobasic cate gories: tractor-trailer units used inmines with lowterrain gradients, (Figs. 3and4)andmodified hard rock enddump trucks used inmines with steeper terrain gradients (Fig. 5). Both ofthese types ofunits have significant economic short comings, andinview oftheprevious rather modest total market sizeforcoalhaulers, itisunderstandable thatnove*Numbers inparentheses designate References atendof paper. ABSTRACT High labor andoperating costs have ledtothedemand for more reliable andproductive equipment. OSHA isfurther de manding safer, quieter, andcleaner working conditions for theoperator. AfleetofKress 150-ton single unit, rearengine, bottom dump coalhaulers, now inoperation attheCaptain Mine, are aninteresting solution inmeeting these demands. Byelim inating theweight ofthegooseneck, hitch, andtractor frame, andusing 175,000 psiyield steel, these units have payload to weight ratios ofapproximately 3:1. This isbetween 60-90% improvement over conventionally designed tractor-trailer units. This new coal hauler design concept became possible with thedevelopment ofadual tirefront axlemodule which in cludes anoleopneumatic suspension and90degsteering capability.Theautomatically leveled suspension system hasa20in stroke, allowing relative deflection rates 1-1/2 times softer than thesoftest passenger cars. This increases vehicle operat inglife,improves tirelife,provides exceptional driver com fort, andallows safe50mph plusoperating speed. Sufficient power isavailable tomaintain thishighspeed when loaded; which results insubstantial productivity improvements. Theengine inthereargives 65%traction empty and50% plustraction ongrade when loaded. Thisengine location isolates thedriver from noise andvibration. AUremovable components aremodular. Theengine module canberemoved andreplaced inaslittle as3h.Formaximum safety, thedual accumulator hydraulic system allows normal vehicle control even when theengine isdead andonehydraulic system isin operative. Downloaded from SAE International by University of New South Wales, Monday, August 27, 20182 Downloaded from SAE International by University of New South Wales, Monday, August 27, 20183 hiele, previous totheKress carrier, hasbeen specifically tailored tomeet