Practical Safety With A Crane
Nothing ruins a pleasant day quite like a goose egg on your head, or a throbbing finger pinch. Avoiding those things (and, of course, the much more disastrous potential events) is the context of this gantry crane safety article. Don’t worry, it’s OK. I’m not here to preach, just to give perspective.
A gantry crane or hoist is an incredible tool for your shop! It opens a lot of opportunities, yet with every great tool comes responsibility. In this case, hoist and gantry crane safety knowledge. We’re not talking about the fiddly OSHA procedures, rather the practical things to make the work area pleasant, along with best practices for staying safe using a crane.
Focus On The Crane
All the following ideas apply in some ways to any sort of lifting — hoist, crane, whatever. Even jacks. However, for purposes of this discussion, we’ll focus on gantry style cranes like in the plans store, shop tools section. These are more than hobby style cranes with a design to take on the really tough jobs, but they still have limits, and can pose some interesting dangers.
Perhaps more important for this discussion are the little things that make a bad day. I can’t tell you how many times I’ve ended up with a blood blister or a bruise because I didn’t quite think through what I was doing.
Let’s face it, a good shop is full of little dangers. It wouldn’t be fun if everything was perfectly safe. A crane is a big tool, and it’s all around us when working. Above with the beam, trolley, loads, and winches — then below to interfere with our feet — and to the sides as well. Understanding and managing the little risks make it more fun. That’s where some simple thoughts about gantry crane safety come in.
Gantry Crane Safety Ideas
Here is our list of things to help in safety with a gantry crane. It’s not definitive, and it’s not all inclusive. However, it is broken into 2 parts — we’ll call them the ‘Big Risks’, and the ‘Be Smarts’. Big Risks are the ones that can potentially change your life, and the Be Smarts are the ones that can potentially give you a bad day.
The Big Risks
We can’t ignore the big risks when talking about gantry crane safety. As mentioned, these are the ones that can change your life. Don’t short-cut these.
- Always work well within the specified load limits — all of them. You should know the load limits of every piece, and work only to the weakest link. If the hook on the cable is the weakest link, don’t exceed it — even if the crane is capable of much more.
- Crane capacity is important, but there are a lot of pieces to consider — like the Lifting Mechanisms. The trolley (for a gantry crane), a chain fall, a come-along or winch, load leveler, etc.. Failure in any of these components equals disaster. Choose appropriate tools for the job.
- Crane height (leg extension) and width change the crane capacity. Know it before you lift.
- Another big one for gantry crane safety — Level lifting. If the crane is not lifting straight and/or level, the forces will apply differently. Having legs at a little bit of an angle will significantly reduce capacity. You might think the crane has 6000# capacity, but at a little angle, the real capacity is perhaps only 1500#. Please don’t do this.
- On the topic of Straight and Level, if you build a crane, please make sure it is built Straight and Square. No need to waste your time building it if you don’t take the time to do it right. See Hints to Achieve it. While on that note, also make sure the welds are complete, penetrating and strong.
- Legs with wheels. We all like the idea of casters to roll a crane around, but those casters put the leg load just off center and significantly weaken the leg. It also puts a lot more stress on the upper joint where the top beam connects to the leg. Wheels on the legs that carry the load significantly decrease crane capacity.
- Be super careful with overhanging loads. We talk about this just a little with our Beam Connector Clamp and ask that you don’t buy it if you aren’t smart enough to use it properly. Sometimes it’s the only way to accomplish something, and it’s great when you need it, but WOW, things can go wrong in a hurry if you don’t do it right.
So, those are the biggies. For gantry crane safety, please don’t short-cut them.
These are the “Be Smart” items that help the job go better, because gantry crane safety is about more than just the catastrophic failure modes. While not usually life changing, these items can make a bad day.
- Rolling load. It’s convenient to lift a load, then roll it around. The big risk, is above, however, there are two ‘Be Smart’ parts as well. First, if the crane is on wheels, then it’s possible for it to start rolling while lifting — before you’re ready. Second, when rolling, the load often swings, and that has its own issues (see below). Be very careful with rolling cranes, and make sure you can stop the rolling when needed.
- Avoid crane and tool bump hazards. The crane and some equipment is usually overhead — like the chain fall, winch, or come-along. Make sure they are well marked, or padded, and generally out of the way. For example, I really like my Winching Pole, but I have bumped my head on that thing many times. Not sevier, but I’ve learned to wear a hat when working around it.
- Avoid trip hazards. By nature, the crane is all around the project. That means the feet can pose a trip hazard, so paint them bright, or add flags or keep them away from the immediate work area. A piece of plywood set against them can tell the subconscious brain to avoid them.
- Dynamic loads. Big loads that swing, bounce, or spin are a recipe for disaster. This item can be in the Big Risk list also. A bouncing load can easily place 3 times the load on a crane and lift. Swinging loads are similar, and if they hit something, they can cause lots of unnecessary damage. For safety, practice careful load control.
If it seems like these are common sense, you’re right. However, common sense is not so common, so they’re worth talking about.
Built In Precautions
Sometimes the best approach to safety is to build in the safety mechanisms. For instance, most machines have guards or interlocks. The Gantry Cranes here at Mechanical Elements have a few built in safety measures like the spring loaded wheels.
Wheels under a crane are really nice, but they also contribute to failure modes. Read more in the Wheels section of Gantry Crane Failure Modes. To avoid that, at Synthesis we mount the wheels with limits, set by springs, to increase gantry crane safety.
Springs allow the crane roll when empty, but when lifting a significant load, the crane sets firm on the ground. In our design, the spring allows freedom to move with a lightish load, but not with a heavy one. For instance, the crane in our shop has springs set at about 125#. That means a center load of less than 500# can roll, but above that, the crane sets down secure. We think a 500# load is something we can control appropriately, but don’t want the risk of something like 1000# moving around.
Establishing a minimum telescoping leg overlap also contributes to gantry crane safety. This is built-in with our crane plans. Using less internal overlap can lead to compromised function (legs wobbling or not standing straight up). The length of the feet are another example. Theoretically a gantry crane needs only small feet, but for the practical side, and the safety side, longer is better.
Proper Build For Strength
Gussets are another great automatic precaution. Don’t underestimate their value in strengthening beam intersections. Both, top and bottom. It’s very common to see huge gussets or angle braces at the bottom (to the feet), but they are frequently missing at the top. Look at this image. While it looks good, a design without extra beam bracing at the top is kinda stupid. [And yes, I can say that, because I did stupid once, and the joint failed. A gusset like the one in yellow (image near the top of this page) increases joint strength drastically.]
To me, the crane in this photo is just dangerous — lacking strength in the top joint, and it’s on casters. When it’s lifting something near the 3 ton capacity, I don’t want to be anywhere near — especially if they try to move it with the load.
What Happens When You Don’t Respect Your Crane?
That’s the million dollar question. “If I had only stopped one minute earlier . . .” . In a fraction of a second a crane failure will significantly change the scenery. As mentioned above, it might be inanimate damage only, or it might be life altering. The problem is we can’t choose the outcome.