Deciding how to do a job and developing your rigging plan are often the most important parts of a project. There can be several different options and making an informed decision may make the difference between a successful job and a lost job.
Cranes are probably one of the most common and useful pieces of equipment on any construction site. They are powerful and technologically sophisticated machines and can lift very large, heavy loads to great heights.
But what about when you need to move a heavy load horizontally. In many circumstances it’s better, even necessary, to use a Hydra-Slide® instead of a mobile crane. But the question remains, how will you know when to overlook the crane and use a skidding system instead? Well, to best answer this ponderable, you need to consider a few things about the nature and scope of your project and the jobsite itself.
Space limitations– A crane is a very sizable piece of machinery. Many times the crane you need to lift a load is larger and heavier than the load itself. As an example, if you need to move a 150 ton transformer you may consider using something like a Terex AC700 crane. This crane has the capacity to lift the 150 ton at about a 36’ radius. However, by itself, it weighs about 300 tons and is approximately 40’ wide and 80’ long. Your infrastructure might not be able to accommodate something that large and heavy. You may also have to deal with overhead wires or obstructions. Ground load bearing pressures can be extreme and need to be considered as well. That’s when you need to consider a Hydra-Slide. This skidding system has a very low height of maximum 8 inches. These systems are ideal for working in spaces with limited clearance and the load weight can be spread out over a large area. The strong steel track is rigid and can carry loads over unsupported spans, depending on the weight of the load. It’s also customizable and you can build track sections in various lengths to suit your application. So, measure what space you have and what your ground bearing capabilities are, then you’ll be able to see if you need to slide rather than lift.
Transportability – Large cranes can be difficult and expensive to move, even short distances. Often they have to be dismantled and shipped in smaller components to meet road weight restrictions. This means that they also have to be reassembled at the jobsite which can be a formidable rigging job in itself. There is always the question of availability. You need to keep in mind where your jobsite is and if you intend to use your own crane or rent one locally. Will it be there when you need it?
The Hydra-Slide may be your best bet in this case also. A 500 ton capacity system can be transported on a single truckload. Its setup, use and breakdown are designed to be simple and safe. Its lightweight design makes transporting the system fast and easy, significantly reducing your mobilization costs
Costs – Cost can be a significant factor in deciding on your Rigging Plan. Cranes, being a very high-value asset, are be very costly whether they are working or not. A small delay on your job can result in expensive crane standby charges. We don’t have to tell you that your budget is often a very difficult thing to manage, if not the most difficult, and weather or equipment delivery delay can eat up your profit. That’s why you have to make smart choices when purchasing or renting equipment. Many times, moving heavy loads with a skidding system has been proven to be more cost effective than lifting with a crane.
Safety – We have left this item to last but in fact it is likely the most important aspect of any rigging job. The safety of workers and personnel should be held above all other concerns. Next is the safety of the load itself and the environment. A crane operates by lifting and maneuvering the load with it freely suspended and balancing it against its own weight. An inaccurate load weight estimate can result in an overloaded crane. The extreme potential and kinetic energies developed by lifting and moving large loads can have disastrous results. A heavy load dropped form even a few inches can seriously damage itself and anything/anyone around it.
With a skid system, your load is never freely suspended and all movements are slow and controlled. When properly set up, your load can never move on its own. Since your load is supported from below and not cantilevered, a slight variation in the weight usually has little or no effect on the stability or capacity of the system. Should there ever be any type of failure in the hydraulics or propulsion system, the load simply stops moving until the failure is corrected and then the move continues again.