Boom dollies are a great solution for transporting cranes. Sometimes they are the only solution.
A boom dolly is needed in two situations. The first is when the crane axle loads exceed the allowable loads or the axle spacing is not long enough for the crane to meet the bridge laws for the states or provinces in which it is operating. The second situation is when a crane can be legally moved without a dolly, but a dolly is used to carry some of all of the crane’s counterweight, eliminating the need for a counterweight truck. In this case the boom dolly makes the operation more efficient.
The first scenario often involves large scale all-terrain cranes and the second scenario is generally with truck cranes. Crane owners also need to determine if counterweight can be hauled on the crane or dolly by the states in which they are operating.
But there are instances where even with a dolly the crane cannot be legally moved in certain areas, according to Tony Niese, vice president of Nelson Manufacturing.
“In this case a boom launch trailer can be utilized to remove the boom during over-the-road transport and then installed upon arrival at the job site without the need for an assist crane,” he said. “The need for a dolly and even the dolly type and axle configuration is dictated by the local axle weight requirements.”
For example, a 200-ton capacity AT can most likely be moved in New Jersey or New York without a dolly at all, he said.
“This same crane in Texas or British Columbia may only need a tandem axle dolly while in Illinois it may need a tri-axle,” said Niese. “Move this same crane to California it will need a 2 + 1 wide spread. Minnesota may require a quad axle dolly with four closed coupled axles. If this crane were to be operated in Alberta it would likely be equipped with a 3 + 2 five-axle rolling tower dolly.”
Suffice it to say, there is much more to it than “I need a dolly for my crane,” Niese said. There are many variables.
Transworld Manufacturing’s Crystal Dieleman put it this way: “Each state has unique bridge and weight laws, and crane models can be configured differently depending on those laws. A boom dolly is ideal to spread the weight of the crane over more axles to legal[ize] the equipment in different areas.”
Dustin Hutson, who sells boom dollies for HMR Supplies, said a boom dolly allows heavier cranes to distribute weight over more axles allowing for travel down weight-restricted roads and bridges.
“In the Midwest there are frost laws that also change the amount of weight each axle can have during the spring and fall when we have freezing and thawing,” he said. “This varies state to state and is something each purchaser should consider when designing a boom dolly to ensure they can travel where they need to go, especially if they travel over state lines.”
Gustavo Anzola, sales manager of Greenfield Products, said because each state has its own regulations for self-propelled mobile cranes, a boom dolly for a specific crane model may look and work completely different depending on the region it will be working in.
“The gross weight for these machines typically exceed the permitted weights and the assistance of a boom dolly is needed to spread the gross weight over additional axles,” he said. “Boom dollies vary in the number of axles and axle spacing which depends on the specific state(s) DOT over-weight regulation the crane and boom dolly may be working in. There is rarely a one-size-fits-all solution.”
Recently, boom dolly safety has been called into question, specifically in Canada. Boom dolly manufacturers take these questions and safety seriously.
“We spend a considerable amount of resources ensuring that we design and build the safest and most reliable products possible,” said Niese. “We look at everything from structural integrity to operational procedures and everything in between. We are constantly looking at customer feedback to look for safety enhancements that they feel we should include.”
Nelson produced a “Boom Dolly Safety Guide” that addresses potential for dolly brakes to be released and the dolly rolling unintentionally, potentially pinning the operator between the front of the dolly and rear of the carrier.
“This has happened when the dolly connecting procedure was not followed and the wheel chocks that Nelson supplies with its dollies were not used and when the air lines supplying air to the dolly were not connected correctly,” he said. “Even though three or four things need to be done incorrectly for this situation to occur, this is a very real concern and should be taken seriously. Nelson dollies are now equipped with a secondary brake interlock valve that will prevent this potential hazard.”
Safety is the number one priority when designing a boom dolly, according to Dieleman. “Backing up the crane/dolly is where damage most often occurs so this is why we have dedicated so much R&D towards developing a reverse steering option and the articulation limiter strap,” she said. “However, safety in design can only go so far. Manufacturers strive to make cranes and dollies foolproof, but inevitably education and a safety culture is the most important. An accident usually is a culmination of several deficiencies.”
HMR Supplies’ Hutson suggested that after determining if the connection is correct that users need to train and practice how to use the boom dolly.
“A lot of time we all assume that ‘I have done this before,’ ‘I’ve driven a truck and trailer,’ or ‘I’ve driven the other crane and dolly,’ and this doesn’t mean that the new crane and dolly will behave in the same manner,” he said. “Differences in length, suspension (spring versus air), castering axle options, [they] can all impact how that crane and dolly will drive and handle. Spend a little time in the yard and make sure the connection is secure and the driver/operator is comfortable maneuvering the new configuration around. I also recommend having someone follow the crane in the yard to make sure everything looks setup correctly, it appears to trail properly [and the like.]”
Last year the Crane Rental Association of America (CRAC) started a Boom Dolly Safety committee.
“We are committed to addressing the concerns of how a crane and dolly handle when traveling over the road,” said Niese. “In our opinion there are numerous factors involved in these concerns and we are working with this committee so that actual testing can be completed.”
When looking at axle weights, Nelson assures that its designs must have a minimum of 60 percent of the weight on the crane axles and a maximum of 40 percent on the dolly axles.
“This 60/40 rule helps ensure that the crane is in control,” said Niese. “Our team is also working on an additional initiative to improve handling of the dolly and will begin testing soon. We do not want to offer this enhancement to the market until we are confident that we are in fact improving handling and not creating something unforeseen.”
Not like driving a crane
Travelling with a boom dolly is not the same as driving a crane.
“The two units must work in harmony together and the driver must be conscious of this delicate relationship,” said Dieleman. “To legally move north of 200,000 pounds with multiple axles and up to 100 feet long is no easy feat. As machines get larger and longer, today’s operator has to be aware of changing conditions and must take more variables into consideration.”
Relationships are important, Hutson said.
“If you have a solid foundation with the crane manufacturers you can easily get the information that is needed and utilize your internal team of engineers and fabricators to make sure all of the pieces work together,” he said.
However, as crane and components increase in size and weight, care must be given by each group to minimize any potential issues, he said. “This is why there is no ‘standard’ dolly,” said Hutson.
This has also led to a new category of equipment that is often referred to as “boom launchers.”
“Sometimes the boom is too heavy to put on a dolly and removing it is easier and more cost effective,” Hutson said. “As the cranes continue to get larger, heavier and longer this product line may become more popular.”
Boom dollies are complex pieces of equipment, and working with the individual crane OEMs is critical, Anzola said.
“Everything starts in engineering to ensure all the extreme and worst load case scenarios are taken into account on each design,” he said. “The two main components of a boom dolly, the base (chassis) and tower (piece that connects to the boom) undergo 3D computer analysis to detect any potential issue and to confirm stress levels are within the design allowable. The connection points to the boom (boom brackets) are typically pre-installed by the crane manufacturer but in some cases they are not. If boom brackets are provided, these need to be reviewed and approved directly by the crane manufacturer.”
Designed for safety
Another aspect on the safety of a boom dolly is the connecting and disconnecting procedure of a boom dolly.
“Proper training and review of the operator’s manual is required to ensure the safety features added to the boom dolly are utilized properly,” Anzola said. “Greenfield Products’ designs include a spring brake valve that must be actuated prior to releasing the brakes of the boom dolly. There has been instances in the past where the boom dolly brakes immediately release inadvertently after connecting the brake lines to the crane. The spring brake valve is typically installed on the passenger side of the boom dolly and requires the oiler or operator to walk to the side of the dolly to release brakes. This allows the personnel to get out of harm’s way before releasing the boom dolly brakes.”
All Greenfield boom dollies are equipped with wheel chocks that are required every time a boom dolly is disconnected from the boom.
Boom dolly safety is a concern because they are designed to travel with the boom over the cab/front instead of in a trailing mode.
“Due to the weight limits imposed on these cranes, boom dollies must be as light as possible but also offer the strength required to withstand the many different road conditions it is exposed to,” said Anzola. “But all boom dolly safety starts with the properly trained and careful driver/operator understanding his road path, ground conditions and the unique aspects of driving a crane on a public highway.”
The variables in the crane, road requirements and related make a universal “off the shelf” dolly unrealistic.
“Nelson offers several somewhat “standard” chassis with our most common axle spacing and features,” said Niese. “We are stocking many of the more standard boom towers and lower chassis weldments to ensure a quick turnaround for our customers.”
But these stock components work for only about 40 percent of applications, he said.
Dieleman said most of TransWorld’s boom dollies are designed for a specific crane in a particular region.
“Each crane model is different and can be configured several ways,” she said. “One crane in one area might need a two-axle straight-frame dolly, whereas that same crane in another area might require a three-axle articulating boom dolly. We do pre-build common frame sizes so that we can cut down our lead time.”
HMR boom dollies have standardized air suspension, allowing for a suspension travel and a smooth ride, Hutson said.
“Most of the design work goes into the tower(s) that connect to the crane,” he said. “This design work is critical to ensure proper mating to the crane and to ensure the dolly can handle the forces that are generated while moving, stopping and turning.”
For the most part, boom dollies are crane-model specific.
“Boom dolly design changes from crane manufacturers and also changes within their crane model family,” Hutson said. “For example, the Grove GMK line may have three or four different boom dolly configurations that are not interchangeable.”
Demand for boom dollies is solid, although 2016 was not the best. Most OEMs envision a slight improvement in 2017. Hutson said market rates for cranes wax and wane, but the market is stable. As structures get higher and components get heavier, larger cranes will be needed.
“As these components need to be transported all over the world and there are weight restrictions on the majority of roads the market for boom dollies will remain strong,” he said. “We have started to see interest from customers internationally as several countries have started to invest significant money into their infrastructure (roads, sewer, water, electrical, fiber) and they do not want to damage it by driving cranes and other heavy equipment over the roads where those types of rules or laws did not exist or were not enforced previously.”
Anzola said the need for boom dollies has been consistent.
Demand is steady
“No major changes in overweight permit or regulations has boosted sales or the need for a specific crane boom dolly,” he said.
“Demand for boom dollies is directly related to new crane sales. Since the oil price dip in late 2014, demand has decreased but it is relatively steady.”
Nelson has a long history in the boom dolly business and their philosophy has helped propel them in the markets they serve.
“At Nelson our philosophy is not ‘here is what we have to offer’ but ‘what do you need?’ Our goal is not sell a boom dolly or trailer to a customer but to sell them a solution to their transportation needs. It is not a benefit to anyone to sell a product to someone when it does not meet or exceed their needs. The knowledge of our staff is the number one reason why Nelson provides the best crane transportation solutions in the industry.”
Dieleman said TransWorld’s crane background helps it compete.
“TransWorld is the only manufacturer to have been a crane owner for over 70 years,” she said. “We built boom dollies and other specialty crane transporters for ourselves when they were not available from outside sources. We had the opportunity to operationally test prove our designs on our own fleet for many years because we had a full-service fabrication shop, an engineering team to compliment a fleet of over 80 units and employed some of the best operators and heavy haul drivers. Although not servicing a fleet of cranes anymore, we still have the passion to consistently produce the best product on the market. We are constantly looking for ways to improve our product line. Our numerous patents support this.”
HMR Supplies views the dolly as an engineered solution that should save time and money.
“Most people view the boom dolly as a necessary evil,” said Hutson. “We excel at engineering a custom dolly that helps the customer work smarter and more efficiently. That is why we work hard to learn how the customer is using the equipment and then provide a solution that works for them. We have been building quality engineered moving equipment for almost 30 years and have a proven track record of quality, durability and customer service. The other advantage we have is that one of our sister companies is a crane service so we use the products we design, engineer and fabricate.”
Greenfield has taken steps to innovate and add features to boom dollies that were not previously available, Anzola said.
“Greenfield is recognized for its availability on units that may seem custom built but due to having material on-hand and production flexibility, we are able to manufacture units from the ground up very efficiently,” he said. “Greenfield also stands out when the boom dolly solution requires further investigation with DOT and regulations to make the crane and boom dolly road legal.”