Du Pont rings aid John Deere

Motor Equipment News - - DIESEL INDUSTRY NEWS -

Trac­tor man­u­fac­turer John Deere makes use of the ex­cel­lent fric­tion and wear be­hav­iour of seal­ing rings made of DuPont Ve­spel in its pi­o­neer­ing dual-clutch Direc­tDrive Trans­mis­sion (DDT) with eight pow­er­shift speeds.

These rings pro­vide a low-leak­age seal against oil pres­sure of up to 20 bar at oil tem­per­a­tures of be­tween -30 deg.C and 80 deg.C with tran­sient peaks of up to 110 deg.C over the en­tire ser­vice life of the trans­mis­sion.

John Deere, one of the world’s largest agri­cul­tural machin­ery man­u­fac­tur­ers, is of­fer­ing this par­tic­u­larly ef­fi­cient and en­er­gysav­ing DDT sys­tem, which per­mits di­rect gear shifts without any in­ter­rup­tion in trac­tion, in its 6R se­ries of six cylin­der trac­tors.

In John Deere’s Direc­tDrive trans­mis­sions, the Ve­spel rec­tan­gu­lar seal­ing rings are lo­cated at the wet clutch pres­sure oil trans­fer points on the shafts of the two sub-trans­mis­sions.

As a spe­cial­ist from John Deere’s Power Train En­gi­neer­ing ex­plains: “When the clutches are hy­drauli­cally ac­tu­ated, the rings pro­vide a re­li­able seal for these pres­sure oil trans­fer points. As this hap­pens, the con­di­tions change at the seal­ing points. When the clutch is dis­en­gaged, the rings are ex­posed to low rel­a­tive speeds be­tween the shaft of hard­ened and ground 20MnCr5 steel and the clutch hous­ing with no pres­sure.

“When the clutch is en­gaged, the rel­a­tive speed is zero, while the dif­fer­en­tial pres­sure is at its high­est. In both cases, the ma­te­rial’s very low fric­tion and very low wear help to en­sure low-main­te­nance op­er­a­tion of the trans­mis­sion. More­over, DuPont’s rec­om­mended ring de­sign min­imises leak­age.”

DuPont and John Deere have closely worked to­gether in or­der to se­lect the grade of ma­te­rial and tai­lor the the dimensions of the groove and the rec­tan­gu­lar cross-sec­tion of the rings. The DuPont devel­op­ment team se­lected a Ve­spel grade with a low co­ef­fi­cient of ther­mal ex­pan­sion to pro­vide a con­sis­tently high seal­ing ac­tion over the en­tire tem­per­a­ture range. With its very high creep re­sis­tance and ex­cel­lent fric­tion and wear be­hav­iour, it con­trib­utes to the par­tic­u­larly low-main­te­nance op­er­a­tion of the trans­mis­sion.

Peter Bergmann, Euro­pean Trans­porta­tion mar­ket seg­ment leader, DuPont Ve­spel & Kal­rez, adds: “This suc­cess­ful col­lab­o­ra­tion with John Deere is another demon­stra­tion of how com­pa­nies can ben­e­fit from DuPont be­ing a one-stop-shop able not only to man­u­fac­ture the ba­sic ma­te­rial Ve­spel but also to masspro­duce high-qual­ity parts. As a re­sult, we are par­tic­u­larly flex­i­ble in re­spond­ing to spe­cific cus­tomer re­quire­ments and in rec­om­mend­ing the most suit­able ma­te­rial from our range of grades which are specif­i­cally tai­lored for dy­namic ap­pli­ca­tions. Once the ma­te­rial has been se­lected, we can rel­a­tively quickly pro­vide sam­ples for cus­tomer test­ing and for com­po­nent in­ves­ti­ga­tions in our lu­bri­cated wear and fric­tion Cen­tre Of Ex­cel­lence, so help­ing to en­sure short devel­op­ment times.”

DuPont man­u­fac­tures the seal­ing rings, main­tain­ing very tight tol­er­ances, us­ing its pro­pri­etary di­rect-form­ing process. The de­sign of the butt joint ge­om­e­try pro­vides low leak­age over a wide op­er­at­ing range and fa­cil­i­tates assem­bly. Without com­pro­mis­ing on re­li­a­bil­ity, rings of this kind help to save on costs, in­stal­la­tion space and weight in com­par­i­son with metal com­po­nents in nu­mer­ous trans­mis­sion ap­pli­ca­tions.

John Deer 6215R trac­tor

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