This is the most common question that people ask when it comes to craning something.
There are a lot of factors that come into play. Understanding those factors will help you pick the right crane for your lift.
There are two major factors that have to be answered before you can choose your crane.
- What is the distance you are craning?
- What is the weight of the heaviest object(s) the you are craning from that spot?
To determine the answers to these questions, you have to answer a series of other questions to place everything into context.
Where is the crane going to be placed?
Knowing where the crane is going to be placed and how it is going to be positioned in that spot are critical pieces of information. It determines the starting point of your distance calculation. Is the crane going to be parked on the street, in the driveway, or off the neighbouring property? When the average crane has a maximum reach of about 100-120 feet, the answer to this question can radically change the math on the distance calculation. The starting point is ALWAYS calculated from the middle of where the crane rotates, NOT the end of the crane truck.
Where is the crane trying to reach too?
This is the end of your distance calculation. The biggest mistake people make here, is they only measuring to the end of the item. You are really need to measure from where the hook is attached to the object, which 9 out of 10 times is the middle of the object. The bigger the object (i.e. pool) being craned a long distance, the more important this is.
Did you take the crane outriggers into consideration?
When the crane is deployed, it has outriggers that come out of the side of the crane. These help stabilize the crane and prevent it from tipping over sideways. The larger the crane the bigger the outrigger footprint required. Where you are planning to park the crane, does it have space for these to extend out the side?
Is the ground level for the crane to park on?
Most people do not realize the crane has to be level for it to work safely. A crane that is not level, is an accident waiting to happen. Most mobile cranes have outriggers that come out the side to balance and stabilize the truck. Those stabilizers have a limited distance of movement that they can lift the crane, if the ground is too uneven, you might not be able to level the crane. If the ground is on too steep an incline, you might also not be able to deploy it where you want it. That could increase the distance you need to reach, if you also have to reach over some unsafe ground.
Is there any height obstructions?
Your standard stick crane, usually cannot lower its boom more than 45 degrees without risk of falling over. That means a couple of things:
- The crane can never reach out the full length of the boom, because for every foot out, it also has to go up.
- If there is a tall object beside the crane truck that is has to go over, two things might happen.
- The crane needs to move further away, so the angles still work, increasing the distance the crane needs to reach.
- The crane reach is reduced, because it has to reach taller to get over the object in question. Meaning the angle of degrees that the boom can bend down has been reduced, because crane is blocked by say a house or tree.
While the crane itself, can move side to side, the crane can only extend forward in one direction. That means that if there is an object like a tree or power line in the way, it also has to go over them to reach where you want to go.
We should note here that knuckle cranes do not have the same restrictions that your standard stick crane has. Knuckle cranes do not have the 45 degree restriction on them and have powerful jib attachments built into the boom for changing direction and increasing the amount of reach it can lift. On trickier or tight lifts, you should always talk to a knuckle crane specialist to see what is and is not possible.
What is the weight you are trying to lift?
The most important thing to understand when craning, is that the weight that the crane can lift is constantly changing depending on a number of factors. To simplify this into layman’s term: the further you want to reach, the less weight you can lift. Or the more weight you want to lift at distance, the bigger the crane you might need to do it.
For example, a crane that can lift 5000 pounds at 20 feet distance from the crane truck. It might be only 2000 pounds at 50 feet distance and 500 pounds at 100 feet distance. Every crane truck has what they call a load chart of how much weight it can lift at what distance. While some trucks have similar charts, every chart is custom designed for that specific crane truck. This is why knowing the weight and distance is so important. A bad guess here can mean the difference between success and failure.
I have the weight and distance, what is next?
Give those numbers to the crane company, along with some pictures of what you think you need. Let them tell you what crane you will need. While you might think you know which crane you need, you do not want to be caught ordering the wrong size. If you guess wrong, you will have to pay for that crane. Regardless of whether the lift was done successfully or not. In the crane business you are paying for crane time and that includes the time for the wrong crane to show up at your job site. Let the crane professionals confirm that your numbers make sense, so you always get the right crane, the first time.