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1982 Grove AT1100 110-ton Hydraulic Truck Crane
Hydraulic truck cranes are mobile cranes that can lift thousands of pounds using hydraulics. Hydraulics relies on forces being transmitted through oil pushing the boom’s pistons in opposite directions to lift thousands of pounds.

Hydraulic truck cranes are essential to building major projects: bridges, buildings, airports, roadways, and more. What would take hundreds of men and hours to accomplish, a crane can do in minutes.


[edit] History

Cranes have played an important part in constructing houses, buildings, cities, and nations throughout history. Structures such as the Pyramids in Egypt have likely been constructed with the help of cranes to lift even the heaviest of materials in what can only be described as feats unimaginable to man.

The earliest representation of a crane appeared during Ramses’ reign in Egypt in 3000 B.C.—a portrayal of a lifting device used to collect water—but the first “cranes” appeared in Ancient Greece and were used to build an entire nation in the fifth century B.C.

Cranes were made of wood until designers building dockyards decided they needed something bigger and stronger. In 1834, cranes were developed using cast iron by a firm called Hick & Rothwell in Bolton, England. This machine was able to lift up to two tons. Wire rope was added to the crane during the same year by Herr Albert Sr., an Official of the German Superior Board. The wire rope meant the crane was stronger and more durable, enabling cranes to have a higher capacity for lifting heavy weights. Wire ropes were weaved together to create an even more powerful capability with the added benefit of flexibility. Germany also decided to build cranes using cast iron; the first one was built in Neuburg four years later.

Joseph Monier came up with the idea of embedding wire mesh into concrete to increase the strength of cranes. He noticed that concrete could handle the pressure of weight but not the traction, but with his alteration he was able to create something that worked efficiently.

New projects like the building of bridges and railways meant cranes needed to get with the times. William Fairbairn from Great Britain came up with the idea to rivet two arch-shaped jibs on a crane. His creation was successful in developing a device more stable and capable of safely lifting weights and he patented the idea shortly thereafter.

Cranes became mobile in 1868 when the firm Aveling & Porter thought of mounting cranes on top of automobiles. The steam traction engine and steam roller production company named the first mobile craneLittle Tom,” which was produced in 1874. Little Tom had a two-ton capacity and could pick up items and carry them.

The first lattice beam on a gantry crane was the result of bridges being built in Germany during 1874. It was the first time any crane had been made of iron but designers found that this material helped the crane deal with the stress.[1]

1999 T340 40-ton Hydraulic Truck Crane

[edit] The Evolution into Hydraulics

Although cranes had come a long way, the onset of World War II forced man to become more inventive. But it would not be until 1946 that British crane manufacturer F. Taylor & Sons would produce the first hydraulic crane. Although it was used within the company and could not luff or slew, it opened doors for a 42 and 50 Series when it joined with Coles in 1959. The mobile hydraulic crane was placed on a Morris W.D chassis.  Taylor & Sons hydraulic crane operated on cylinders that were lifted and lowered as well as a boom powered by a hydraulic pump. When the company could no longer use army vehicles as a chassis for the crane, production began for its very own mobile hydraulic cranes.

During the 1950s cranes were celebrated as devices that could rebuild what bombs from the war had destroyed—homes, cities, and even countries. Hydraulic systems became more and more complex with gear systems and pumps that could be powered while trucks remained immobile. The first truck loader crane made its appearance from companies such as Hydrauliska Industri AB

The A2 crane was introduced in 1952. This model was essentially a crane mounted on the back of Chevrolet truck complete with hydraulic lifting cylinders and hooked winch. This loader crane started a trend and Atlas Weyhausen, a company located in Bremen, started producing similar versions.

Cranes were now becoming more advanced, with companies and manufacturers making the winches more precise, developing telescopic booms, improving the hydraulic pumps, and utilizing different materials to change the way the crane was made.

A hydraulic truck loader crane that consisted of a fitted winch could slew and lift up to a ton. This creation by Steinbeck Moosburg was an example of how complex designs were becoming.

A company called Liebherr developed a series of cranes known as the 14A and 25A series—they were self-climbing cranes with special hydraulics embedded into fitted masts.

The more a crane could do, especially at the same time, the more popular it was. Demag Zug built a crane with a 2.5-ton lifting capacity but it also had hydraulic cylinders that provided rapid movement in the luffing boom; several different movements could be performed simultaneously.

[edit] Hydraulic Mobile Cranes Throughout the Ages

1996 Link-Belt HTC8665 65-ton Hydraulic Truck Crane
Gottwald’s hydraulic cranes became important to their further development. The HMK 120 in 1959 was a step in another direction. By this times, the bigger the crane, the better. The HMK 120 had a tower, raised cab, and a luffing jib.

By the time the 1980s had arrived, cranes were everywhere and every construction company was scrambling to carry one better than the next. Equipment companies such as Caterpillar and International were even mounting cranes on tractors, an up-and-coming trend.

Making cranes bigger was still important, as can be seen by the largest crane of this time, the Hydra Husky 36/40TSC.[2]

Perhaps the most important change was the way cranes were used and valued. Prior to the war, crane trucks were valued for how reliable they were—they had to be during a time of such strife. After the war, emphasis was placed on how comfortable the cranes were for the drivers, cranes that carried maximum results for the smallest maintenance and costs. Being able to operate the hydraulics of cranes was of paramount importance and such machines like the 65 hydraulic lattice boom crane, created a frenzy for their usefulness and features. [3]

[edit] Features/How it Works

Hydraulic truck cranes are different from other types of cranes because of the way they operate. Instead of using a winch to wind up cables to provide the force of lifting, hydraulic cranes rely on oil. Oil is a fluid that retains its volume. It is incompressible and thus one of the best fluids for pushing pistons towards the direction the force is going to be exerted. The hydraulic pump creates the pressure that will move the piston, an action that is maneuvered by controls in the operator’s cab. Hydraulic truck cranes typically use a two-gear pump.

The boom, a large arm-like structure, is the part that does that actual lifting. It contains several sections,including counterweights to weigh down the crane so that it won’t tip once the crane attempts to lift heavy weights. The counterweight can generate up to 1,400 pounds per square inch (9,653 kPa). The boom can lift up and down as well as right to left.[4]

Because the crane is mounted on a truck, it is able to travel many distances from job to job and has little dismantling involved. It has a single engine that controls both the truck and the crane itself.[5]

[edit] Other Parts

  • Jib: a latticed structure that extends from the boom.
  • Outrigger: a part that helps maintain the crane’s balance by lifting the truck with the help of hydraulics.
  • Rotex gear: The boom can swivel on this gear, located under the cab and also operated by hydraulics.
  • Load movement indicator: lights that flash to the operator to indicate that maximum weight is approaching.
  • Pump: responsible for steering the outrigger.
  • Steel cables: these are reinforced cables that run through the boom and the jib. They can generate up to 14,000 pounds (6,350 kg).[6]
  • Boom swing: this large ball or roller is attached to the carrier and swings 360 degrees in both directions. The swing is controlled by hydraulics and can provide swings at varying speeds for revolving the turntable gearbox.
  • Boom elevation: the crane’s boom ascends by double hydraulic cylinders that can be lowered and raised.
  • Boom telescope: another hydraulic operation that helps the boom extend or retract.[7]

[edit] Common Manufacturers

[edit] References

  1. Bachman, Oliver, and Cohrs, Heinz-Herbert and Whiteman, Tim and Wislicki, Prof. Alfred. The History of Cranes. KHL Group:Hanover, 1997.
  2. Bachman, Oliver, and Cohrs, Heinz-Herbert and Whiteman, Tim and Wislicki, Prof. Alfred. The History of Cranes. KHL Group:Hanover, 1997.
  3. Higgins, Lindley R. Handbook of Construction Equipment Maintenance. McGraw-Hill Co. Inc.: New York. 1979.
  4. Hydraulic Crane. 2008-09-24.
  5. Peurifoy, R.L and Ledbetter, W.B. and Scnexnayder, C.J. Construction Planning, Equipment and Methods. 5th Ed. McGraw-Hill: New York, 1996.
  6. Hydraulic Crane. 2008-09-24.
  7. Higgins, Lindley R. Handbook of Construction Equipment Maintenance. McGraw-Hill Co. Inc.: New York. 1979.