Make your crane worthy of your company’s investment
Structural steel erection is one of the most critical phases in any building project’s erection. Equipment used in the erection of steel is the cornerstone to success. Today’s modern business model not only requires, but demands that capital expenditures on equipment must make sense in terms of profitability and practical utility as the intelligent tool of choice. The modern steel erector contractor must be business savvy to make a crane worthy of their company’s investment. This holds true not just for today, but over the entire economic life of the machine.
The choices available to buyers are staggering. How to choose? If the crane is too small, too much time and money is lost in constantly moving and re-positioning the machine when a larger machine with a larger operating envelope and radius would have done the job more efficiently from one work position. A machine may also be too small to lift heavier sections into position. The machine is under capacity. This creates delays and requires that the contractor rent a larger capacity machine creating high on-the-job equipment costs which erode the contractor’s profits.
Single versus multistory
Typically, as a rule of thumb, companies that erect single-story steel structures up to 1,000,000 square feet and multistory structures up to six stories would probably go with mobile cranes in the 40- to 75-ton range. These machines have hydraulic, telescoping boom sections and are mobile by virtue of being mounted on either conventional trucks or as truck-mounted units that are factorybuilt, nonconventional trucks.
For multistory construction, lattice booms are often utilized with as much as 170 feet of main boom and 60-foot jibs. Tower cranes would be used for heavy lifts or high-rise construction, typically in downtown construction sites in metropolitan areas where space is limited and the tower structure of the crane is meant to overcome the restricted space of urban job sites.
Smaller single-story projects may run from 5,000 square feet to 180,000 square feet. Buildings are either conventional frame design or preengineered metal buildings. These projects may utilize cranes with lighter lift capacities. Often, steel erectors will utilize a smaller 18- to 19-ton crane and a second larger capacity 30- to 50-ton boom truck. These units can be mounted as boom cranes on conventional tandem or singl-axle truck chassis. Some companies may choose to go with all-terrain or rough-terrain units. These machines require special transport to job sites as they are not road-able.
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The 18- to 19-ton boom trucks typically have 70 feet of hydraulically telescoping main boom with 80 feet of working tip height. Jibs are typically two-stage 40-foot jibs, which gives the operator a total of 120 feet working tip height. The larger 30- to 50-ton units can have main booms from 112 feet up to 155 feet and jibs running from 46 feet to 55 feet. Offset jibs offer an additional advantage for reaching over roof rafters to set roofing and purlins in back bays.
In addition to the boom trucks and cranes used to lift steel into place, the final piece of the puzzle is the forklift. A telehandler or rough-terrain forklift may be used to feed steel and construction materials to the boom trucks already set in work position, and to provide flexibility in unloading and moving materials delivered to the job site. A telehandler can unload a 30,000-pound truckload of steel in 40 minutes and then be used to shake out the material, placing the material in its proper place for the boom crane operators, stacking rafters and columns, and using the forks of the telehandlers to lift materials without need of slings or chokers.
Telehandler pluses
The advantage of the telehandler as an assistant and helper for the boom crane is huge. No longer must a crane be used to unload material when its time is better spent lifting steel into its proper place.
Speed, timing and coordination all benefit from using the right tools for the right job. The size and capacity of lift machines are determined by the size of the job and materials to be used. Planning must be done to assure that the crane has the proper radius and lift capacity to reach critical areas. Never stretch the crane’s capacity to 100 percent. As a rule of thumb, jobs should be planned whereby maximum loads lifted are approximately 75 percent of the cranes capacity.
While all steel erector contractors seek 100 percent utilization of their lift equipment 100 percent of the time, sometimes there is downtime. When this occurs, it is commonplace to lease equipment to other contractors to keep it working.
Bob Masiak is senior sales executive at Giuffre Bros Cranes Inc., Milwaukee. For more information,
visit www.giuffre.com.
