Views: 0 Author: Site Editor Publish Time: 2023-02-23 Origin: Site
There are four main types of mobile cranes here: truck mounted,rough terrain,crawler and floating.
The most basic truck-mounted crane configuration is the "boom truck" or "truck loader," which features a rear-mounted rotating telescopic boom mounted on a commercial truck chassis.Larger,heavier,specialized "truck-mounted" cranes consist of two parts: the carrier, usually called the lower section,and the lifting components including the boom,called the upper section.They are connected together by a turntable,which allows the upper to swing from side to side.These modern hydraulic truck cranes are usually single engine machines,with the same engine powering the undercarriage and the hoist.The upper section is usually powered by a hydraulic system with a pump mounted on the lower section running through a turntable.In older model designs of hydraulic truck cranes,there were two engines.A man in the lower section pulls the crane over the road and runs hydraulic pumps for the outriggers and jacks.The one on the upper level runs the upper level through its own hydraulic pump.Many older operators prefer twin engine systems due to leaking turntable seals on aging new design cranes.Hiab invented the world's first hydraulic truck-mounted crane in 1947.The name Hiab comes from the commonly used abbreviation for Hydrauliska Industri AB, a company founded in Hudiksvall, Sweden in 1944 by Eric Sundin, a manufacturer of snowboards who discovered a way to provide loader cranes with truck engines using hydraulics. method of motivation.Generally,these cranes are capable of driving on the highway without special equipment to transport the crane unless there are weight or other size restrictions (such as local laws).If this is the case, most large cranes are equipped with special trailers to help spread the load over more axles, or be able to disassemble to meet requirements.An example is counterweights. Usually, the crane is followed by another truck to haul the counterweight removed for travel.Also, some cranes are capable of removing the entire upper.However, this is usually only a problem with larger cranes and is mostly done with conventional cranes such as the Link-Belt HC-238.When working on a job site, outriggers extend horizontally from the chassis and then vertically to level and stabilize the crane when it is stationary and hoisted.Many truck cranes have a slow travel capability (a few miles per hour) when hanging a load.Great care must be taken not to swing the load sideways from the direction of travel, as most rollover stability depends on the stiffness of the chassis suspension.Most cranes of this type also have moving counterweights for stability in addition to that provided by the outrigger beam.Loads suspended directly from the stern are the most stable as most of the crane's weight is used as counterweight.The crane operator uses a factory calculated chart (or electronic safety device) to determine the maximum safe load for stationary (cantilever) work as well as (on rubber) load and travel speed.Truck cranes range in capacity from about 14.5 short tons (12.9 long tons;13.2 tons) to about 2,240 short tons (2,000 long tons; 2,032 tons).While most can only rotate around 180 degrees, more expensive truck-mounted cranes can rotate 360 degrees.
The boom of the rough terrain crane is mounted on a landing gear atop four rubber tires and is designed for off-road pick-and-carry operations.The outriggers are used for level and stable lifting of the crane.These telescopic cranes are single-engine machines,with the same engine powering the undercarriage and hoist, similar to crawler cranes.The engine is usually mounted on the undercarriage rather than on the upper part like a crawler crane. Most have 4-wheel drive and 4-wheel steering and can traverse tighter, smoother terrain than standard truck cranes with less site preparation.
The boom of crawler cranes is mounted on the chassis,which is equipped with a set of crawlers to provide stability and maneuverability.Crawler cranes range in capacity from approximately 40 to 4,000 long tons (44.8 to 4,480.0 short tons; 40.6 to 4,064.2 tons).The main advantage of crawler cranes is their ease of movement and use, as the crane is able to operate without outriggers on site with minimal modifications and is stable on its tracks.Wide tracks spread weight over a large area and are much better than wheels at traversing loose ground without sinking.Crawler cranes are also capable of traveling with a load.Its main disadvantage is that it is heavy and difficult and expensive to transport.Typically, large tracked crawlers must be disassembled into at least the boom and cab,and then moved to the next location by truck, rail car or ship.
Floating cranes are primarily used in bridge construction and port construction,but they are also used occasionally to load and unload particularly heavy or cumbersome cargo on and off ships.Some floating cranes are mounted on the pontoons, while others are specialized lift barges with a lifting capacity in excess of 10,000 short tons (8,929 long tons; 9,072 tons) used to transport entire bridge sections.Floating cranes are also used to salvage sunken ships.Crane vessels are often used in offshore construction.The largest slewing crane can be found on SSCV Thialf, which has two cranes with a capacity of 7,100 tons each (7,826 short tons; 6,988 long tons).For 50 years, the largest such crane was the Long Beach Naval Shipyard's "German Hermann," one of three built by Nazi Germany and captured in the war.The crane was sold to the Panama Canal in 1996 and is now known as Titan.