application (BMA)wouldbeusedtotransmitsignificanttorqueoververyshortdurations,withheat generationabsorbedonlybythethermalcapacitance ofthesurrounding material.Researchrevealedno calculations wereavailabletodetermineyieldloadsinwormdrives,andafiniteelementanalysismodel forthiscomplexgeometryandcontactsituationwouldhavebeenunruly.Inordertogainconfidence in designmargins,astaticultimateloadexperiment wasrunsimilartothatfortheplanetgearsaboveusing theHOSsets.Again,testingshowedthatafactorof5existedabovethebasicsingletoothinbending calculations withnoapparentdamagetothewormandsomedeformation ofthesoftgear.Afactorof8.3 existedintheHOScasebeforetheteethofthegearshearedoff(usinghigh-pressure lube,52%final efficiency). Afactorof4abovethesingletoothinbendingonthegearwasassumedasaconservative limitpointformargincalculations forHOHsystems,thoughavalueof5or6mayhavealsobeen acceptable. Dynamic T_sting Thenextphasewastotestthedevelopment unitusingactualdutycycleinputsandoutputs. Dynamic testingoriginally showed thattheEverlube _620Cwasstableandwouldmaintain efficiency through repeated hightorquecycles. TheactualBMAdutycyclewas60revsforward, noload(approx. 1.13-3.39 N*m(10-30in*lb)inthefixturesetup),2forward outputrevsramping from0to135.6N,m(0to1200 in.lb),apartialrevolution reverse ramping from135.6to0I_m(1200to0in°lb),and62revsreverse, no!oad(again,1.13-3.39 N*m(10-30in°lb)inthefixturesetup). Whenasignificant number oflowtorque cycleswerecombined withthehightorqueramps,theEverlube ®begantoshowsignsofdistress, though itwasfeltthatitwouldlastfortherequired 16MOQuallevelcycles. Thisdistress wasmostlikelyaresult®oftowefficiency atnoload. Thelubrication properties ofEverlube actually improve withload,andthe MOefficiency atnoloadwasinthe20%range. Thislowerefficiency allowed moreabrasion totakeplace which,combined withsignificant cycles,caused areduction intheamount ofEverlube ®remaining inthe wormcontact zone. Duringtestingitwasalsonoticed thatsomerunsweremuchbetterthatothersfromanefficiency standpoint, andoncetheefficiency dropped off,itwouldnotreturnuntilthepiecesweregritblasted and re-coated withEverlube ®.Aftersignificant iterative testing, itwasdetermined thatBraycote _601EF_ whichwasusedinallbearings andonthespurgearsurfaces, hadadetrimental impactonEverlube in theslidingcontact situation oftheworm.Afreshwormset,carefully handled andinstalled intotheBMA, wouldperform repeatedly withtheexpected peaktorqueefficiency of40-50%. Placing onefingerprintof Braycote _onthesurface oftheworm,andcarefully installing itintotheunitsoasnottofurther contaminate thepiecewouldresultinarapidreduction, andthendegradation, ofthewormsetefficiency. Sincetherewasnopractical waytoprevent exposure ofBraycote _toEverlube _inthisdesign, andthere wasinsufficient timeandresources toobtainanewgreaseforthebearings andgearsandthenproveit compatible withEverlube ®,asearchforanewwormlubrication method wasundertaken. WC/CCoatina Asearchforhardand/orlubricous coatings thatcouldbeusedoverthesystem temperature range,ina vacuum, withlowoutgassing, compatible withallmaterials intheBMA,andapplied belowthe315°C (600°F) tempering temperature ofthePyrowear ®wasundertaken. Apotential solution wasfoundat Balzers ToolCoating, Inc.,(Amherst, NY)through useofanewvapordeposition coating calledTungsten Carbide, Carbon (WC/C). Thiscoating wasapplied 1-4microns thickatlessthan260°C(500°F) and obtained anRc68hardness. Thebaseproduct reportedly hadacoefficient offrictionagainst drysteelof 0.15to0.30.Ifrunagainst itself,thefrictional valuesroughly halved. Itdidhaveanadvertised break-in periodbeforeobtaining thelowerfrictional values. 84