Infrastructure Projects - Construction Technology
A Practical Guide to Construction Techniques and Practice
I can't pass a construction project with a big red crane without wanting to jump out of the car and take a picture. I know that's just me, but everyone associated with the planning and execution of these projects should be familiar with the basic tools that are required.
This particular crane is a real workhorse. It is a crawler crane, and it gets that name because it is mounted on these caterpillar tracks. The crane is mobile. It can travel short distances on those tracks, but it's mobility is limited. It certainly can't go out on the street and move some distance to the other end of the project. That would not be feasible. But within this limited space, it can travel back and forth and service all of the work within this limited area. It's very high capacity because it is mounted on these caterpillar tracks. The load is spread out, makes the machine very stable. It is the perfect tool for these circumstances.
The other feature I will mention to you is that it has a lattice boom. The boom comes in sections. When this crane arrives on the job site, it only has one small section attached to it. Then the boom is assembled on the job site to whatever length you need to satisfy the requirements of your project. So this is a crawler mounted crane.
There are many similarities with this crane, but the most noticeable difference is that this crane is mounted on rubber tires and this is called a “truck-mounted crane.” It also has the lattice boom, which needs to be assembled on the job site and when the crane is actually making a pick, it must be supported on its outriggers, as shown in this photo. The crane really has a very limited capacity on the rubber tires and it should never be used on its tires. The outriggers must be put in place before you make a pick.
Because it's on rubber tires, it is much more mobile. It can travel some distance, but in reality, if you've assembled a very long boom at the end of this machine, to get out on a public street and travel, the boom has to be flat out horizontally. You can imagine it's very difficult to maneuver. Under some circumstances it might be relatively simple to get from point A to point B, but out in the city street, I can't really imagine a fully assembled truck crane traveling around with freedom.
The third variety of crane differs significantly from the first two, most notably in that the lattice boom has been replaced by a collapsible boom. This immediately solves the problem of mobility, because this boom will simply collapse. The machine is mounted our rubber tires. and this is the most maneuverable and mobile occurring that you can select. You see them out on every job site because of their versatility. With the boom collapsed, this can travel at highway speeds and then when it gets to the site where it's needed, it can extend the boom and go to work in a matter of minutes. This makes it a extremely useful tool.
There's another important feature here, perhaps not noticeable to the layman, but very important to the contractor. There's a single cab which houses the operator. The operator operates the crane from this position, but he also drives the crane around from this position. The result is that this tool is manned by only one person, whereas the previous truck mounted crane requires two people. You have immediately cut the labor force in half and you've achieved far greater mobility. That's why you can't go by any construction site without seeing one or more of these hydraulic cranes. They are routinely called Cherry Pickers. Perhaps that's the name that you know them by. These machines also have outriggers, and should always operate with the outriggers extended.
The only trade off in using a hydraulic crane, especially one of this size, is that it does have limited capacity. However, this is a modest-sized hydraulic crane, and you can get a hydraulic crane in just about any capacity you want.
Here's the other extreme. This is a hydraulic crane. It also has a collapsible boom. When you look at it, it looks about the size of a locomotive. Nevertheless, you can collapse the outriggers, and you can drive along the highway with this. Although, my guess is, when you have selected a machine of this size, you probably need permits to drive down the highway. This certainly looks like an oversized vehicle, but I've gone to the extreme. The hydraulic cranes are available in a range of sizes to fit your needs. This crane would be limited to one single massive pick and then you would send it away and replace it by a more versatile crane.