It provides a base for both lattice boom and telescopic boom cranes ranging in capacities from 5 tons to well over 500 tons.Ī second type of truck carrier is the rough terrain (RT). This carrier type has proven to be the most diverse. Its heavy-duty suspension and power train are designed primarily for highway travel and for graded jobsite roads. The first is called a truck carrier and has the ability to travel long distances on public highways. Wheeled carriers come in three basic types. For larger cranes, the upperworks or house is designed to be detached or undecked from the carrier to facilitate transit moves. The upperworks of smaller cranes are permanently mounted to the carrier. Via the machinery deck, the upperworks are mounted to the carrier's (or crawler base's) turntable. The upperworks consist of the hoisting mechanisms, swing mechanisms, hoist engine, and boom mounting-all of which are fastened to a structural frame called the machinery deck. Strictly speaking, crawler "carriers" are not usually referred to as carriers but rather crawler bases and consist of a structural frame called a carbody, a turntable, and crawler treads.
The largest telescopic cranes (800 tons and up) require additional trucks to carry boom, outriggers, and counterweight.Ī carrier is what makes a mobile crane mobile and basically consists of a special truck chassis, turntable, and wheels. The setup time is still significantly shorter than that required for comparable lattice boom cranes. Depending on local highway laws, when telescopic cranes reach the 180-ton range, additional trucks may be needed to carry counterweights. The larger the crane, the longer the setup time required and the less mobile it is on site. Size effects play an important role in the time required for setting up a telescopic boom crane. Most European manufacturers can also provide an elaborate lattice extension called a luffing jib attachment, which essentially converts the crane into a tower crane. To extend reach height even further, lattice boom extensions are frequently added manually to the tip of the telescopic boom.
Crane lift radius full#
Once at the site, the boom can be extended to full length in a matter of minutes. The boom segments nest inside one another and are easily retracted to roadable lengths. Telescopic cranes are almost always mounted on wheeled carriers. The primary advantages of the telescopic boom cranes are portability and rapid setup time. As with a fishing pole, deflection of a telescopic boom is significant even with low loads. In addition, at low boom angles, the dead weight of the boom contributes significantly to overturning. However, at low boom angles, the telescopic boom's capacity decreases rapidly because of limited bending capacity. (For high boom angles, the internal loading is mostly compression.) As such, they are extremely strong and have a high lift capacity when almost vertical. Telescopic booms, on the other hand, carry their load as flexible, cantilevered box beams, much like fishing poles.
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