SC&RA COMMENT: The route to safety
12 March 2019
Since 2017, when SC&RA formed its Boom Dolly Task Force, the Association has been working collaboratively with the Crane Rental Association of Canada (CRAC) to mitigate risks in the use of boom dollies with mobile cranes.
Beth O’Quinn, SC&RA Sr. Vice President, Crane & Rigging, explained that the Boom Dolly Task Force’s mission is to educate members on proper procedures and reduce risks, as well as develop best practices and training materials.
“The goal is to increase awareness of the special and unique considerations boom dollies add, above and beyond driving cranes with booms in their normal position of being over the carrier,” she stated. “The effort has required SC&RA, and all parties involved, to develop a thorough understanding of the driving dynamics of cranes with conventional truck suspensions as well as hydraulic (all-terrain) suspensions, which includes: operating procedures, connecting to crane, brake adjustments (if any), preparing for highway travel, travel precautions, and returning to normal crane operation.”
To that end, keeping the load under certain restrictions as it moves is also very important, as there are myriad laws and safety concerns when it comes to moving around equipment so large. Thus, if a company can move the crane boom with the outrigger boxes, swing-away jib, block, ball and necessary counterweight, they will save the entire operation valuable time during the setup process once everything arrives at the jobsite.
Recognizing that, historically, training is certainly provided for cranes and for boom dollies independently, but not once the two systems are married together, SC&RA has been highly motivated to provide online training courses that address the key issues companies should consider when utilizing both.
Tim Bennett, Vice President at NCSG Crane & Heavy Haul Services, as well as a member of the Boom Dolly Task Force, believes that industry faces multiple challenges when operating boom dollies.
“The boom dolly was brought on as a means to meet weight restrictions for road ways and bridges,” he explained. “But as crane technology advanced over the years, little interface was done to mate the carrier to the dolly – and generic dollies became the norm.”
As a result, Bennett underscored that, where feasible, companies should make a point to appropriately size or mate the boom dolly with the crane. “Avoid the bigger-is-better principle; running a tandem/tandem, or tandem/tri dolly with a smaller crane, such as a 130T, and you’re asking for the tail to wag the dog.”
Bennett also emphasized the need to invest in training. “Most crane operators are not ‘truckers,’ let alone have experience pulling a trailer with multiple pivot points. Tail swing is one of the most overlooked parts of the training for crane operators driving these things down the road.”
He added, “Remember the reduced steering and braking points – this should translate to reduced operating speeds and best practices on how to operate with.”
Bennett emphasized that companies utilizing boom dollies should remain focused on the weight transfer to the dolly and extra load capacity as a result.
If you’re in the market, Alan Schmidt of Tadano America Corporation indicated that, for companies planning the purchase of a new boom dolly for a new all-terrain crane, don’t assume that the cheaper options available will get the job done. In fact, long-term maintenance costs, downtime and safety issues can all be easily avoided with a little planning on the front end.
“First, remember that a boom dolly is a trailer, and the best practice for pulling a trailer is with the use of a hitch,” he said. “While many crane carriers either come with or have an option for a pintle hook, most boom dolly brackets are robust but not designed for the task of pulling. The use of a tow bar connected to the pintle hitch reduces the possibility of damage to your expensive boom. The method of pulling by hitch is a common practice in Canada, but in the USA, pulling by boom is the most common practice.”
Schmidt maintained that the connection between the boom dolly and boom should be such that it supports the weight of the boom but also allows for the motions that the boom produces during the travel of the vehicle.
“As you think about your boom’s journey, consider a few questions: Where is this unit going to travel? Is the topography relatively flat or is it very hilly?” he said.
While a flat travel route produces no ill effects, Schmidt pointed out that a hilly route can be cause for concern. Travel up and down hills can produce large departure and ascent angles. If the attachment between the boom and boom dolly is unable to compensate for this, it will produce unwanted stresses on the boom, boom dolly and boom-dolly attachment.
“Beyond the terrain that your crane will be travelling on, the number of axles on your boom dolly is also a consideration,” said Schmidt. “The main goal here should be choosing a boom dolly that provides for the lowest cost of ownership and easiest cornering of the unit. When a three- or four-axle dolly becomes necessary, the ability of the third and fourth axles to easily follow is important.”
While these considerations may cost your company more initially, they’re worthwhile, said Schmidt, in that they produce significant benefits: “They reduce potential for damage … which means more uptime on the jobsite working instead of spending it doing repairs.”
Risk vs. reward
Most companies that offer boom dollies do so with a few options to choose from. HMR models are available with single, split and tilting tower options. Three- or four-axle dollies are also available when the overall weight requires a little more to be touching the ground during transport.
These days, boom dollies can be modified and customized depending on the customer’s needs for the project or the type of crane they’re moving. And today’s versions come with an assortment of bells and whistles: storage for spreader beams and outrigger pads, cameras and leveling springs to name a few.
But Bennett admits that this space is still evolving, and while companies will continue to reap the rewards of new innovation, they should pay close attention to the risks – and prepare accordingly.
“There’s a lack of available formal training in driving and handling a crane with a boom dolly,” he confirmed. “And some folks misuse the dolly as an additional hauling trailer for counterweights and other items. It’s also difficult to apply a specification when multiple dolly combinations emerge without specific crane interfaces.
“And people should understand that combined braking can be reduced by up to twenty-five percent when using a boom dolly. Similarly, steering angles can be reduced by upwards of thirty percent.”
His advice? “Work with your industry association on developing best practices. SC&RA (Boom Dolly Task Force) and CRAC both have active committees working on these recommendations. Look at integrating smart technology into the dolly and having it interface with the carrier. ABS systems, anti-roll, swing-out alerts and trailer-brake manual valves in the carrier – as examples. But mostly, get informed – get involved.”