What is the Maximum Wind Tolerance of Mobile Cranes?

16 April 2019

While a site foreman looks down at a mobile crane’s wheels to see if the ground is firm, the wind is getting up. And while a chargehand is checking for power cables and other boom obstructions, that wind is turning into a howling gale. The operator sees what’s going on here, sees how the gusts are rocking the boom, and he’s already asking the right questions.

What Is Wind Tolerance?

In this context, where mobile cranes are being hit by a strong breeze, wind tolerance is deemed a safety margin, one that’s applied to a crane-mounted vehicle. As a worst-case scenario, picture an incident where this safety factor goes unheeded. The wind rises until it’s hard for a worker to stand, and a crane chassis rocks. Worse yet, the boom is extended. As the gale force atmospherics receive a few extra kilometres per hour of force, the mobile lifter topples on its side. Operator harm is likely. Property damage is another issue, then there’s the likelihood of more serious harm, as incurred by a nearby work team. For example, the extended boom could’ve swept forward and brought down a scaffolding tower. This incident, while thankfully hypothetical, would’ve been unacceptable, which is why maximum wind tolerances are always strictly observed.

Determining the Maximum Wind Velocity

Measured in kilometres-per-hour or metres per second, the value isn’t necessarily absolute. True, some nations and crane manufacturers quote velocities. A 36-kph maximum is one example of this approach to the matter. Otherwise, the maximum wind tolerance velocity is commonly printed on a mobile crane manufacturer’s load charts or user manual. A loading stability factor should also be on the chart, along with the boom extensibility ranges. The lack of a fixed velocity isn’t hard to figure out, not when we look at cranes. It’s just, there are so many factors to assess. The boom could be solid or made of lattice strips. Outriggers increase chassis stability, so there’s that to remember. Also, winds behave differently. A strong gale is one thing, then there are the unpredictable gusting effects to consider. At the end of the day, the loading factor and maximum wind tolerance rating should both be known by heart. That way, an operator isn’t left scurrying for a lost manual or a scraped away loading poster.

On-site, the head office has a wired fence. It’s full of store building materials and tools. Looking up, the office has an anemometer whirling on a mounted rod. This little spinning instrument measures windspeed velocity. However, it can’t forecast a change in the environment. To do this, the crane operator can call the office, then someone will get on the job by calling up the meteorology centre and getting a wind advisory report.