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BSI complete iheels fittings draft
Page 6
Page 7
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• The first draft of a quality standard for wheel fittings is now complete. The standard is de signed to cure mystery wheel loss.
Research into the standard, by wheels expert Don Wright, was funded by Commercial Motor's Wheel Loss campaign, which raised a total of ZI3,000.
According to Wright the aim of the standard is to "improve the accuracy, strength and durability of wheel-fixing components, thus improving reliability and security over long periods of time".
The BSI hopes that if hauliers only buy trucks with BSIapproved wheel components the industry will be well on its way to solving the wheel-loss mystery: the draft will be available for consultation in April.
Many operators are angry that they have been prosecuted for using dangerous vehicles, when they have maintained them correctly, but some have escaped punishment after pleading guilty to wheel-loss charges.
Carlisle-based F Brown told magistrates it had followed the Department of Transport's code on wheel maintenance and was given an absolute discharge (CM 28 Nov-4 Dec 1991).
Bradford-based Speight Skip Hire was found not guilty of running a vehicle with dangerous parts even though both nearside wheels had come off. The court accepted that the wheels could have become detatched because of dirt trapped between the faces (CM 5-11 Dec 1991) The draft BSI standard will propose: El Production conformity: nuts, bolts and studs to be manufactured in line with strict quality control procedures.
CI Dimensions of flat-faced nuts (spigot-type wheels): manufacturing dimensions with tolerances have been specified: a 24mm thread size is called for. CI Dimensions of cone-faced nuts: tolerances specified for cone angle, inclination of cone axis and parallelism of the cone axis to the thread axis.
0 Tolerances for DIN nuts (spherical-faced nuts): tolerances set out for concentricity of spherical radius and thread axis, although in general DIN will have to conform to the existing German DIN standard.
0 Dimensions of studs and bolts: laying down tolerances and sizes of fillet radii and the avoidance of radii cut radially into the shank. OCompression test for flat-faced nuts (spigottype wheels): to ensure ad equate strength of nuts with captive washers to avoid collapse of seating between two parts of assembly.
CI A wedge test for bolt heads and collars on studs: to ensure wheel bolt heads are strong enough.
0 Torque/tension performances for flat, cone and spherical-faced nut fixings: as wheels will be taken off and retightened at least 100 times in the life of a truck, fastenings will have to generate a minimum clamping force although this is likely to require a lubricant.
London-based Range Transport was cleared of running a dangerous vehicle by Harrogate magistrates after one of its trailers lost two wheels on the Al (CM 1-7 Aug 1991). It says that having a standard to follow could have prevented the incident: "Our lorries have been operating on studs not sufficient for the job," says a company spokesman. "We think the standard is a good idea — something we've been needing for years and years."