In our forklift maintenance and safety feature, we look at cracking and corrosion in older equipment
Speaking at the Workplace Health and Safety Show in May, Crown Equipment general manager – product development Mike Croxford said metal fatigue can be caused by either the machine’s age or wear and tear caused by its operating environment.
“The first sign of metal fatigue is usually you get cracks that start to grow in welds and welds in structural areas, and they would tend to be on your mast mounts, your drivetrain mounts in your chassis, and can be in other areas that are loaded depending on the types of fork trucks,” he said.
“Typically, if you have a cracked weld, it may be feasible to repair it, and usually that repair would involve grinding the weld out and providing a preparation so you can do a full penetration weld to get the original strength back in the structural joint.”
Repairing a crack in this way is usually feasible if the crack remains solely within a weld, he said.
“Where you have a crack that’s penetrated through the parent metal that the weld is supporting, that’s when you need to have a structural assessment,” he said.
It may be possible to stop a crack in the parent metal by using a method like the “end drill” method, where a hole is drilled through the parent metal at the end (or tip) of the crack.
“However a crack can be fatal [for the equipment] if it’s penetrated into the system so far that you cannot make a repair where you can guarantee the safety of the equipment.”
These include protective structures like overhead guards, which can never have the integrity of the original when repaired – as the standard to which they are tested is a destructive one that cannot be replicated.
“What we usually recommend with customers when they are looking at the condition of older equipment is to clean down the truck, remove the paint and do an initial inspection of the weld through something like a dye penetrant test to identify any infantile cracks or any surface cracks,” he said.
“If you find cracks, it’s worthwhile to follow that up with a more rigorous approach, whether it be through a mag particle test, through an X ray or something similar, where you can see the depth of penetration of cracks.”
Croxford said when these issues are found the best first step is to consult the manufacturer, or if they no longer exist, a structural engineer.
Assessing levels of corrosion on the vehicle, as well as what types of treatments might be available, is also key to safe operation, he added.
“It may be that you need to talk to a corrosion expert about how you can mitigate further corrosion, and if you can do any treatments to repair where there’s significant corrosion,” he said.
Moving parts such as lift chains and mast tilting systems were also prone to corrosion – needing lubricant to get into pins and threaded connections.
“If they’re not maintained correctly, they will rust and get frozen joints. Some manufacturers will provide rubber boots that will protect the tilt cylinders, and I would encourage you, if they’re available, to fit those.”
Where equipment sits unused for long stretches, careful storage is key to ensuring they remain in good condition, Croxford added.
“Some things to consider are if you need to put it up on chocks so that you don’t get flat spots and damage to your wheels, if you need to flush and replace all the fluids in the truck, if you need to grease all the chains and the slides to prevent incidental corrosion while it’s stored. Consideration should also be given to the battery,” he said.