You might have heard recently about the motorist who stopped to investigate a knocking noise under his car and jacked it up to take a look. While he was under his vehicle the jack broke and he was crushed to death.
The media described this as a “bizarre” accident, when it was anything but: every vehicle owner’s manual I’ve ever read includes a warning not to work under a vehicle supported only by a jack.
I remember a similar incident a few years ago described by the media as a “freak” accident. While a man was inflating a tyre on his tractor, the rim exploded and he was killed. But there was nothing at all freakish about the accident. It was a clear case of breaking the safety rules: inflating a heavy vehicle tyre is potentially an extremely dangerous activity.
Most heavy vehicle rims consist of a hub-like section with a separate outer flange secured by a retaining ring. This is because the tyres are large and unwieldy, and cannot be slipped over their rims with the same ease as typical car tyres. In the case of a heavy vehicle, the pressure of the tyre helps seat all the parts of the rim together. So if the tyre is completely flat or partially inflated, the risk of the rim assembly exploding while the tyre is being inflated is relatively high. Which is why the safest way to inflate a heavy vehicle tyre is to place it in a tyre inflation cage where one is protected from flying flanges and retaining rings if the assembly explodes.
If a cage isn’t available, there are some simple safety rules that should always be followed. The first and most important is to visually inspect the flange and retaining ring to ensure they are correctly seated and that the retaining ring is properly clipped in place. Next, avoid standing in front of the tyre while inflating it; instead, use an inflation attachment that doesn’t need to be held inside the tyre valve, so you can stand behind the wheel. That way, if the rim assembly explodes its debris will be projected away from you and the tyre will provide an additional safety barrier.
I’ve lost count of the number of heavy vehicle yards where I’ve seen maintenance staff standing in front of tyres while inflating them; or inflating a tyre off the vehicle when it’s lying flat on the ground with the flange facing upwards. In many cases a tyre cage was available, but was standing unused nearby. The primary issue is one of management and ensuring that people follow the correct tyre safety procedures. Considering the amount of energy stored in a fully-inflated truck tyre, correct inflation procedures are something all fleet managers should consistently re-emphasise.
Rob Handfield-Jones has spent 20 years indulging his three passions: vehicles, road safety and writing. He heads up driving.co.za, a company which offers training in economical and safe driving.