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NZV8 - - CONTENTS -

In re­sponse to the ever-in­creas­ing num­ber of un­safe af­ter­mar­ket com­po­nents hit­ting the mar­ket, the Low Vol­ume Ve­hi­cle Tech­ni­cal As­so­ci­a­tion (LVVTA) has de­vel­oped a pur­pose­built cyclic test rig. The rig, for which the ma­jor fabri­ca­tion work was do­nated by Welling­ton metal fabri­ca­tion busi­ness Met­con, was un­veiled to the pub­lic at CRC Speed­show, where it was con­fig­ured to repli­cate light driv­ing forces on an af­ter­mar­ket tiltad­justable steer­ing col­umn — although this is just one of many uses that the LVVTA has in mind for it. The de­sire to build the cyclic test rig came about as a re­sult of the cat­a­strophic fail­ure of an af­ter­mar­ket tilt-ad­justable steer­ing col­umn in 2013. This fail­ure was traced back to a small plas­tic com­po­nent within the tilt mech­a­nism of the col­umn. From this fail­ure, the LVVTA be­gan the process of for­mu­lat­ing a method by which qual­ity af­ter­mar­ket tilt col­umns could be dis­tin­guished from poor-qual­ity items. While some com­po­nents may eas­ily pass a one-off load test, most au­to­mo­tive com­po­nents un­dergo a high num­ber of cyclic — re­peated — loads. With this in mind, a spe­cial­ist de­sign en­gi­neer was com­mis­sioned to de­sign a cyclic test rig that could repli­cate those loads. The rig in­cor­po­rates an elec­tronic ac­tu­a­tor that can ap­ply loads of be­tween 2.5kg and 60kg, mea­sured by an elec­tronic load cell fit­ted to the rear end of the ac­tu­a­tor. This sends a sig­nal to the elec­tronic con­troller, and all data re­lat­ing to ev­ery move­ment the ac­tu­a­tor makes and the loads ap­plied are recorded. The rig’s de­sign al­lows for col­umns to be tested at a range of an­gles, in­clud­ing their max­i­mum tilt set­ting — a po­si­tion in which they’re of­ten driven in hot rods and pick­ups, and a sit­u­a­tion that cre­ates the high­est loads such a col­umn will re­ceive. Un­like the LVVTA pro­ce­dure for cast I-beam axles, this is a de­struc­tive test, where even a col­umn that passes will be worn and un­suit­able for use in a ve­hi­cle. If a man­u­fac­turer has shown that its pro­duc­tion is con­sis­tent and to a high qual­ity, the re­sult from the cyclic test­ing of one col­umn can be used to jus­tify the in­tegrity of oth­ers of the same make and model. As un­proven and poorly con­structed prod­ucts are be­com­ing in­creas­ingly com­mon in the af­ter­mar­ket, the cyclic test rig has been de­signed in such a way that it can be used for nu­mer­ous dif­fer­ent com­po­nents and is not lim­ited strictly to steer­ing prod­ucts. This will en­able the LVVTA to prove — or dis­prove — the qual­ity of com­po­nents in­tended to be fit­ted to low vol­ume ve­hi­cles. Fur­ther in­for­ma­tion on un­safe steer­ing col­umns, and a de­tailed ex­pla­na­tion of the orig­i­nal col­umn fail­ure, can be found in the Un­safe Af­ter­mar­ket Steer­ing Col­umns info sheet No. 01-2013 at lvvta.org.nz.

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