Tech­nol­ogy and opin­ions change

Suspensions have evolved with needs of ve­hi­cles

Big Rigs - - DRIVE LINE FEATURE -

THE steel spring sus­pen­sion has been used in trans­port since the horse and buggy days.

Airbag suspensions came into be­ing in the US in the 1970s and have been in use in Aus­tralia from around the same time.

Man­u­fac­tur­ers’ “ap­pli­ca­tion guide­lines” from the 1970s spec­i­fied that air sus­pen­sion was an “on­high­way” sus­pen­sion and that it would only be ap­proved for 100% high­way use.

Lim­ited ap­proval was pos­si­ble for off-high­way use, but the sus­pen­sion was not to be used for high cen­tre of grav­ity loads, the guide­lines in­di­cated. Much has changed. Air sus­pen­sion be­came more widely used in the 1990s with the in­tro­duc­tion of the higher mass lim­its al­lowed by the use of “road­friendly” sus­pen­sion types.

In­deed the cur­rent (ex­ten­sive) list­ing of ap­proved “road-friendly” suspensions records more air suspensions than it does spring-based ones.

Air suspensions ver­sus spring suspensions has al­ways been a “hot topic”, with users fer­vently be­liev­ing one is bet­ter than an­other. Thank good­ness Aus­tralia is a democ­racy.

A re­port pre­pared for the NT’s Department of Trans­port and Works dated Septem­ber 2000 com­mented from its op­er­a­tor sur­vey “it was ev­i­dent that no one com­bi­na­tion or ‘set up’ of the com­bi­na­tion ‘out­shone’ any other. Com­bi­na­tions fit the trans­port task and what works for one task does not nec­es­sar­ily work for an­other”.

“Fur­ther­more, what op­er­ates in the more metropoli­tan en­vi­ron­ment does not nec­es­sar­ily op­er­ate suc­cess­fully in re­mote ar­eas.”

A study pub­lished in 2014 by a ma­jor US car­rier con­cluded that “air ride did not guar­an­tee greater ride qual­ity than spring and that it was a myth” that it did.

A spokesper­son for Aus­tralia’s lead­ing trailer man­u­fac­turer and sup­plier, Max­iTRANS, said: “Along with third-party of­fer­ings, Max­iTRANS man­u­fac­tures and fits a num­ber of pop­u­lar pro­pri­etary sus­pen­sion so­lu­tions in­clud­ing VE50 spring sus­pen­sion and AirMAX airbag sus­pen­sion.

“Re­gard­less of make, we fol­low sus­pen­sion man­u­fac­tur­ers’ guide­lines to pro­vide best prac­tice rec­om­men­da­tions to our cus­tomers based on the pro­posed trailer ap­pli­ca­tion.

“Over time, we have seen an in­creased up­take of airbag sus­pen­sion and en­cour­age our cus­tomers to spec­ify it where ap­pro­pri­ate due to the bet­ter ride and re­duced dam­age to roads and in­fra­struc­ture that it of­fers.”

De­spite now be­ing 17 years old, the words of the NT Trans­port and Works re­port hold true; sus­pen­sion “com­bi­na­tions fit the trans­port task and what works for one task does not nec­es­sar­ily work for an­other” but ad­vances in sus­pen­sion tech­nolo­gies are fast clos­ing that gap.

PHO­TOS: BOB RI­LEY

SMOOTH RIDE: Airbags on an IVECO chas­sis give a smoother ride for sen­si­tive prod­uct and height ver­sa­til­ity for load­ing.

Heavy steel suspensions are still favoured for rugged vo­ca­tions.

This vet­eran Ley­land steel spring sus­pen­sion is sim­i­lar in de­sign to the old Mack Camel back.

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