- Average RT Crane Costs
- Rough-Terrain-Crane Specifications: 30- to 65-Ton Capacities
- Grove
- Link-Belt
- Terex
- Haulotte US
- Tadano
The increasing popularity of boom trucks and telehandlers for lighter material-handling chores has pushed the bulk of rough-terrain-crane sales up to machines in the larger size categories. In 2004, North American RT crane sales had risen nearly 20 percent (to about 600 units), and more than half of those sales were 50-ton-and-larger machines, as reported by Cranes Today (www.cranestodaymagazine.com/story.asp?sectionCode=66&storyCode=2027080). With sales action shifting into heavier categories, the four manufacturers competing for rough-terrain business here are working to deliver the best lifting performance and value in the most transportable package.
Most competitors are realizing that formed booms with rounded cross sections, like those prevalent in Europe, can be built stronger and lighter than box-booms. Welding formed halves of the boom together, rather than four plates, eliminates the need for stiffeners. The boom is lighter without sacrificing strength. All of Tadano's RT booms are what the company calls "rounded hexagonal box construction," and Grove builds everything from the 60-ton RT700E and larger with its MEGAFORM boom.
Link-Belt puts formed booms on the Series II machines from the 50-ton RTC-8050 II and up. But a couple of models without the Series II designation in this size range ¡ª the RTC-8060 and RTC-8075 ¡ª remain in the lineup with the BOSS diamond-embossed box boom. There is some inconsistency, though, as the RTC-8065, which is not part of Series II, has the formed boom.
An additional benefit of new boom designs is that they are typically built with wear pads that include Teflon. The boom's sliding surfaces are lubricated as they move across the Teflon, eliminating the need to grease the boom.
All of the Terex rough-terrain cranes are equipped with booms made from welded-plate box sections with embossed side-plate holes, similar to Link-Belt's BOSS boom. But it seems likely that Terex will respond to market dynamics and begin to adapt the formed booms used on its Demag line to the RT line.
New boom designs cut some weight, but even with the counterweights stripped, none of the models in the hot new size range ¡ª the 60 tonners ¡ª will drive up onto a lowboy at less than 72,000 pounds. If you leave counterweights on (none of those machines offers a hydraulic system for removing counterweight), the lightest of the 60-ton machines still weighs nearly 84,000 pounds when stripped, and the heaviest tips the scales at around 92,000 pounds.
Link-Belt's RTC-8065 and RTC-8075 are the smallest machines on the market available with hydraulic systems for handling the counterweight. It's optional equipment on both. They're also made with outrigger beams that can be removed relatively easily. The only other 65-ton crane on the market, Terex's RT665, strips to virtually the same weight as the RTC-8065, but its counterweight is bolted to the frame. Leaving the counterweight on leaves the basic Terex at nearly 86,000 pounds.
Hydraulic counterweight removal is standard equipment on Grove's RT857E, RT890E and the largest-capacity rough-terrain crane on the market, the RT9130E.
Counterweight-handling hydraulics are standard equipment on Link-Belt's RTC-80100 II, as well. The system supports the manufacturer's claim that this machine can be stripped for highway-legal transport in less than 30 minutes without a helper crane. The RTC-80100's six-wheel carrier rolls on 23.5R25 tires, so it is less than 10 feet wide when the counterweights and outrigger boxes are removed. Strip its auxiliary winch and sheave blocks as well, and the 100-ton crane transports at 83,900 pounds. (Without outriggers or counterweights, it can pick and carry 27 tons.)
More rough-terrain cranes are sold in North America than in any other country in the world except Japan. Yet there are only four full-line manufacturers competing for less than 1,000 sales here each year. It's something of a marketing hothouse. When a significant departure from the norm succeeds, it's probably worth taking note. Persistent sales growth of Tadano's premium-priced RTs is one of those interesting anomalies. The company's all-automatic load moment indicator raises questions about what buyers want in lifting electronics.
Today's electronic load-moment indicators (LMI) and anti-two-block systems all have sophisticated safety features. Sensors monitor load radius, boom angle, boom length, and actual load, and a screen in the instrument panel displays that information. The operator indicates how the machine is configured and the current outrigger positions, and the LMI's computer calculates allowable load. It displays the percentage of allowable load at any given moment during a pick.
Audio-visual warnings alert the operator of impending two-block condition, and the computer can disable the control levers before the situation becomes dangerous.
The systems allow operators to preset safe work zones for the crane, establishing limits for swing, tip height or boom angle to avoid hazards around the crane. The computer remembers where it's safe to work and sounds an alarm and flashes a light when the boom is approaching one of the preset boundaries. Some LMIs can disable the controls before violating a defined limit.
Tadano designed its own LMI (which it calls an automatic moment limiter, or AML-L) to do all of these things, too. But the AML-L also allows the operator to extend the outriggers to any length ¡ª in fact, to extend the outriggers on a single machine to four different lengths if that is what suits the jobsite.
The operator of a competitive crane in a situation like this would input the outrigger positions into the LMI, and it would calculate the maximum load the machine can pick based on the outrigger that is closest to the center of the crane's swing bearing. The machine would be able to pick that load from any side of the machine.
Tadano's AML-L has sensors that tell it where the outriggers are positioned. It combines the outrigger position with the crane configuration, load radius, boom length, and boom angle to calculate the maximum allowable lift over each quadrant of the machine based on each outrigger's distance from the centerline. If the outriggers are not uniformly deployed, the load chart changes in each quadrant of the swing circle to reflect the outrigger position in that area.
If the operator picks a load safely over one outrigger and tries to swing over a side of the machine where the outrigger is closer to the machine, or tries to boom out or boom down into an unsafe position, the AML-L knows it. It sounds alarms and flashes warnings. The AML-L is programmed with what Tadano calls a soft stop. As the machine approaches the safe boundary, the computer slows the hydraulics progressively to bring the load to a smooth stop before it reaches a position that could cause the crane to tip.
Crane buyers have to consider many different levels of operating skill, though, and some prefer a simpler limiter that establishes a uniform lift capacity all around the crane. Those seeking more lifting capacity for their dollar will find a variety of features at several price points ¡ª remarkable for a product category supplied by so few manufacturers.
| Web Resources | ||
| Grove www.manitowoccranegroup.com | ||
| Haulotte US www.haulotte.com | Link-Belt Construction www.linkbelt.com | |
| Tadano America www.tadanoamerica.com | Terex Cranes www.terex-cranes.com | |
