Tata Hen­drick­son brings next-gen sus­pen­sion sys­tems

Auto components India - - CONTENTS - Story by: Anirudh Ra­heja

Hen­drick­son, the lead­ing global man­u­fac­turer and sup­plier of medium and heavy-duty me­chan­i­cal, elas­tomeric and air sus­pen­sions, had ear­lier in­tro­duced walk­ing-beam tan­dem truck sus­pen­sion. Later the com­pany in its Chicago fa­cil­ity de­vel­oped new sus­pen­sion sys­tems, based on the walk­ing beam con­cept, called Haul­maax and Ul­ti­maax, to el­e­vate ef­fi­ciency, pro­duc­tiv­ity and safety of com­mer­cial ve­hi­cles. Its joint ven­ture in In­dia, Tata Au­to­comp Hen­drick­son Sus­pen­sions (THSL), launched the new sus­pen­sion sys­tems in In­dia.

Made for In­dia

THSL adapted the Ul­ti­maax and Haul­maax sus­pen­sion types for the In­dian road con­di­tions and mar­ket de­mand. “The Ul­ti­maax and Haul­maax that we have in­tro­duced in In­dia are ca­pa­ble of op­er­at­ing in In­dian con­di­tions which dif­fer from the US. It was not an easy task. To en­sure that both the sus­pen­sion types suc­ceeded in In­dia, THSL em­ployed a rig­or­ous adap­ta­tion process. It could be de­scribed as re-de­vel­op­ing them,” J V Narasimha Rao, VP, Busi­ness De­vel­op­ment, THSL, said.

In 2013, Hen­drick­son bor­rowed ag­gre­gates like rear axles and other in­te­grated com­po­nents from Tata Mo­tors. These were utilised to test the Ul­ti­maax sys­tem on a few ve­hi­cles in the

US. THSL also pur­chased an LPK 2523.K 6x4 tip­per from Tata Mo­tors and fit­ted it with the Ul­ti­maax sus­pen­sion to demon­strate the de­liv­ery pa­ram­e­ters. “We ef­fec­tively show­cased what the sus­pen­sion could do. Work on the sus­pen­sion be­gan in 2014,” he said. Tata Mo­tors car­ried out rig­or­ous tests be­fore rolling out 10 pi­lot CVs last April through its cus­tomers, based on their ge­o­graph­i­cal spread and na­ture of op­er­a­tion. The pi­lots found their way to stone quar­ries, river beds, coal mines, and iron ore mines among oth­ers. “Some of the Ul­ti­maax sus­pen­sionequipped trucks had clocked more than 3000 hours be­fore the mar­ket roll-out,” he said.

The Ul­ti­maax sus­pen­sion em­ploys the walk­ing (equal­is­ing) beam con­cept with patented pro­gres­sive rate spring and has found its way into the new Tata Prima 2525.K tip­per with a 16-cu. m. body. The truck, aimed at con­struc­tion and light min­ing seg­ments, with Ul­ti­maax as its rear sus­pen­sion, prom­ises a dras­tic re­duc­tion in main­te­nance needs and costs.

Claimed to be ro­bust enough to withstand ar­du­ous work­ing con­di­tions, Ul­ti­maax, in empty or light-load con­di­tion, has the shear springs to carry most of the ver­ti­cal load. This re­sults in a con­stant low spring rate and

su­pe­rior ride.

With­out an abrupt change in the spring rate, the ride and sta­bil­ity na­ture of the sus­pen­sion changes to meet the ap­pli­ca­tion needs ac­cord­ing to the vari­a­tion in load. Re­duc­ing road shock and vi­bra­tion, the sus­pen­sion sys­tem im­proves the ser­vice life of the cab, chas­sis and body equip­ment. The in­clu­sion of

a flat-bot­tom de­sign en­ables Ul­ti­maax to get the truck to profit from high ground clear­ance even un­der load.

For tip­pers, which work un­der tough con­di­tions, high ground clear­ance is a ne­ces­sity. Sup­ported by rub­ber bushes in the front and rear, the sus­pen­sion type also elim­i­nates the need for pe­ri­odic lu­bri­ca­tion. It en­ables the truck to carry higher pay­load. The best part is the main­te­nance-free na­ture of Ul­ti­maax.

Aimed at long-haul high­way (truck) ap­pli­ca­tions, the Haul­maax sus­pen­sion type builds on suc­cess­ful tri­als across di­verse ge­ogra­phies. Show­cased on the Tata Prime 3718 10x2 haulage truck at Auto Expo 2018, the Haul­maax sus­pen­sion type, ac­cord­ing to Rao, will be in­tro­duced by Tata Mo­tors on 2 other haulage trucks. These in­clude the Tata Prima 3118 8x2 and Tata Prima 4923 6x4 prime mover. Mark­ing a dis­tinct de­par­ture from leaf spring sus­pen­sion, the Haul­maax sus­pen­sion type is rub­ber-based. It, along with the Ul­ti­maax sus­pen­sion type, is en­gi­neered to en­hance pro­duc­tiv­ity and com­fort.

Pro­duc­tiv­ity, com­fort

In ad­di­tion to en­hanc­ing the pro­duc­tiv­ity and com­fort, the 2 sus­pen­sion types are claimed to re­duce driver fa­tigue as well. El­e­vat­ing re­li­a­bil­ity and dura­bil­ity by a good deal, the 2 sus­pen­sion types are lighter by 300 kg than a typ­i­cal bo­gie sus­pen­sion. With the shear springs and the pro­gres­sive springs, the only bits that need main­te­nance, Ul­ti­maax and Haul­maax of­fer a dis­tinct ad­van­tage, Rao said. The main­te­nance pro­ce­dure for shear and pro­gres­sive springs in­volves check­ing them for signs of fail­ure. The shear springs of­fer a softer un­laden ride. The pro­gres­sive springs en­hance sta­bil­ity un­der load.

Un­like a con­ven­tional leaf spring sus­pen­sion in a tip­per or a haulage truck, which re­quires main­te­nance ev­ery 50,000 to 70,000 kms, the Ul­ti­maax and Haul­maax sus­pen­sion types have a set norm for spring re­place­ment. The pro­gres­sive springs have to be re­placed once their height falls be­low 56 mm. Usu­ally, when a tip­per runs with­out load, and re­turn to the pit, the rough sur­face over which it trav­els, leads to ag­gre­gate dam­age. In the case of Ul­ti­maax, the dam­age to the ag­gre­gates due to ex­cess move­ment and vi­bra­tion is cur­tailed. Even if the driver drives at the same speed, the chances of dam­age are min­i­mal. He can, in fact, do more trips as the com­fort level goes up.

“We ob­served dur­ing the 9 months that we tested the sus­pen­sion on the field that op­er­a­tors made at least 1 ex­tra trip ev­ery day. If the op­er­a­tor is paid on per kg ba­sis, he will earn more. Ve­hi­cle down­time for re­pairs and sus­pen­sion main­te­nance will also go down,” Rao said.

High­way ad­van­tage

The tech­nol­ogy de­ployed to pro­duce Ul­ti­maax and Haul­maax has been patented by Hen­drick­son and in­cludes thin­ner springs and a heat treat­ment process dif­fer­ent from the one used to man­u­fac­ture con­ven­tional leaf springs. “The bushes used in par­a­bolic springs iso­late the body from vi­bra­tions that are in­duced by the road sur­face. I would urge op­er­a­tors not to add leaves. Do­ing this will de­te­ri­o­rate the per­for­mance of a

con­ven­tional leaf spring sus­pen­sion,” Rao said.

“Learn­ing from Ul­ti­maax val­i­da­tion cy­cle will be in­cor­po­rated into the Haul­maax cy­cle. Haul­maax em­ploys rub­ber bol­ster springs cou­pled with pro­gres­sive load springs. The sus­pen­sion type of­fers bet­ter per­for­mance in laden and un­laden con­di­tions,” he said.

Util­is­ing elas­tomeric bol­ster springs and a pro­gres­sive load spring (PLS) that work in syn­ergy to pro­vide out­stand­ing ride qual­ity when the truck is empty, Haul­maax works in such a way that the PLS en­gages and func­tions to­gether with the elas­tomeric bol­ster springs as they com­press to pro­vide the ad­di­tional sta­bil­ity vo­ca­tional ap­pli­ca­tions needed in line with the rise in load.

Like Ul­ti­maax, the Haul­maax also de­ploys a dis­tinct elas­tomeric spring de­sign, which not only helps to pro­vide an ideal bal­ance of ‘empty’ ride qual­ity and sta­bil­ity when loaded. It pro­tects the chas­sis, cargo and body equip­ment from ex­ces­sive vi­bra­tion and road shock due to pot­holes and other road in­con­sis­ten­cies. Haul­maax weighs up to 400 kg lower than a vo­ca­tional rear tan­dem sus­pen­sion. The up to 400 mm of di­ag­o­nal ar­tic­u­la­tion of Haul­maax keeps the axle in con­tact with the sur­face be­low to en­sure su­pe­rior trac­tion and bet­ter off-road mo­bil­ity.

The fu­ture

Con­fi­dent of the ad­van­tages of Ul­ti­maax sus­pen­sion, Tata Mo­tors has rolled out 100 CVs with it. These in­clude a few units of the 2523.K tip­per. Work is un­der way to fit the sus­pen­sion type to Tata 2518. Once done, it will mark an en­try into the mass mar­ket. Jus­ti­fy­ing the cau­tious ap­proach of Tata Mo­tors to­wards the adop­tion of the sus­pen­sion type, Rao said “if we up­scale at the first in­stance, is­sues could arise. For us, they would trans­late into ca­pa­bil­ity or sup­ply chain chal­lenges. Tests are be­ing per­formed also on Signa 2518 and 2523. These 2 are high­vol­ume prod­ucts.”

Em­pha­sis­ing on the suc­cess of its 6-tonne lift axle that has found its way to the Tata LPK 3118 and 3718, he said they are work­ing with Tata Mo­tors to de­velop a 10-tonne lift axle sus­pen­sion for 10x2 and 6x2 trucks and tankers. “We un­nec­es­sar­ily run all the axles on the road. We are there­fore work­ing on a 10-tonne lift axle sus­pen­sion for tankers and bot­tle car­rier seg­ments. We are also aim­ing at tip­pers. This will ben­e­fit them as the dif­fer­ence be­tween a laden and un­laden ve­hi­cle is too high,” he said.

Af­ter the in­tro­duc­tion of an ad­vanced lift axle sus­pen­sion for the Tata 3718, the com­pany is also work­ing on a new lift axle de­sign. Slated for in­tro­duc­tion in 2019, the new lift axle will be su­pe­rior and of­fer more ben­e­fits. THSL is also work­ing with Daim­ler In­dia Com­mer­cial Ve­hi­cles to equip its BharatBenz trucks with a lift axle. The model be­ing con­sid­ered is the 3123R. Aware of the ef­forts CV OEMs are tak­ing to keep the costs down, and in a post-BS IV sce­nario, THSL is work­ing closely with many OEMs to help them cut weight. “A sus­pen­sion weighs about 450 kg. A 10% weight re­duc­tion will be a sig­nif­i­cant change,” Rao said.

Haul­maax is aimed at long­haul, high­way seg­ments

V Narasimha Rao, VP - Busi­ness De­vel­op­ment, THSL is con­fi­dent of Ul­ti­maax and Haul­maax el­e­vat­ing ef­fi­ciency, ser­vice life, safety and pay­load ca­pac­ity.

Ul­ti­maax is ro­bust, and en­gi­neered to withstand ar­du­ous work­ing con­di­tions that CVs like tip­pers are sub­jected to.

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