Excavators and backhoe-loaders spend the vast majority of their time digging and loading dirt or powering attachments. But they can also be periodically called upon to lift and place pipe, trench boxes and other materials into a hole or trench, or move them from one area of a jobsite to another.
Although on the surface this may seem to be a simple "lift and place" scenario, it actually requires some careful planning to ensure the safety of your employees and your equipment. Failing to follow proper protocol, as outlined in the equipment operator's manual, can have devastating results.
The risks of overloading
Prior to any lift, it's vital that you know the weight of the material to be moved.
"An educated operator should not take a guess as to what he's doing," says Paul Golevicz, marketing manager, Kobelco Construction. "He should contact the right individuals on site to find out what the material or object weighs."
When assessing the total weight of the load, be sure to include the weight of the bucket or quick coupler if they will remain on the machine. "The weight of the bucket or coupler has to be subtracted from the total weight that we say the unit can lift at that particular reach or angle," says Golevicz. "A lot of people don't do that, and they end up overloading the equipment."
This can have significant repercussions. "The most serious potential outcome in exceeding a machine's rated lift capacity is tipping the machine," says Bret Jacobson, product specialist, excavators, Liebherr Construction Equipment Co. This can place the operator and any workers nearby or in the trench at risk.
"Exceeding the rated lift capacity of the machine will also result in a decreased service life of the machine," he continues, "especially the load bearing steel structures of the attachment and the swing ring support."
There is the risk of overheating the hydraulic system, which can result in a blown valve, hose or other damage.
"You have multiple lift cylinders, too, and you could end up ruining seals and other components on the unit if it's grossly overloaded," Golevicz states.
In addition, there is the potential to bend the boom, arm or other costly components.
Know your equipment's limits
Both excavators and backhoe-loaders come with published load charts, which can be found in the operator's manual and may be mounted in the cab. Manufacturers can't emphasize enough the importance of staying within these established ratings.
Admittedly, the ratings tend to be on the conservative side. However, engineers do this for a reason, says Golevicz. "There is some overloading capability, because they know the operators will indeed overload a machine," he explains. Without these limits, he adds, "your operator would always be lifting up to the max rating - and beyond."
Continually pushing the excavator above and beyond its ratings presents several risk, says Eric Winkler, marketing manager, backhoe-loaders, New Holland Construction. "You could have hoses or a cylinder go, you could have a boom break, etc.," he points out. "That's why we make sure we have all of our load charts specific to what the machine can do so people aren't trying to pick up 15,000 lbs. when it's only going to pick up 8,000 lbs. We go above and beyond in making specifications a big portion of it."
Of course, when determining whether a particular machine can handle a lift, the operator must factor in more than total lift capacity.
Take excavators, for example. "Load charts are available for excavators. But the contractor must also be aware of the configuration of their machines - short, standard or long arm - to make sure they are reading the correct lifting chart," says Chad Ellis, product and training manager, Doosan Infracore America.
Also consider how far the excavator will need to boom out. "If you're lifting a 10,000-lb. trench box or pipe and you're doing it out at 20 ft., you need to consult the operator's manual to see if the excavator can handle it," says Golevicz.