Ask the Crane Tech: Pre-Use Inspections
As an overhead crane technician, one of the questions I get asked a lot is, "What do I look for on a pre-use inspection?" Well let's look into that today. Completing daily pre-use checks are an important part of having a crane, as not only can completing these checks save time, money, and lives(!) but are also required by occupational health and safety. And when you think about it, it seems completely reasonable to me to take a few minutes at the start of your shift in light of the possible consequences that may result from skipping your daily checks. Let’s take a few minutes from our busy days to discuss what to check and what to look for in a pre-use crane inspection.
STEP 1 - CHECKING THE PENDANT FOR DAMAGE OR WEAR
Make sure there are no holes or cracks in the casing. Press the e-stop button to ensure you do not move the crane and check all the buttons for wear or damage. Press each button to see if they feel right. If you have 2-speed control -- do you feel the detents? Check the pendant cable and strain relief for damage. If all your checks are good, you are ready to release the e-stop.
STEP 2 - OPERATE THE HOIST
When you press the up button, does the hook go up? Does the hook go down when you press the down button? If your answers are yes, then great -- then this step is done!
However, if the hook is going the wrong direction during this first check, there is something very wrong with your hoist; likely the power phasing has somehow been reversed. Do not use the crane and call for immediate service. Using the crane in this condition will almost certainly end up with the hook stuck at the top or bottom, with the possibility of damaging the wire rope and rope guide or burning out the hoist motor. At this point, repairs will become more expensive and the downtime will increase to bring your hoist back to safe operational capacity. Having everything running backwards also presents a safety hazard as the operator will likely press the desired button out of habit only to have the load travel the opposite direction… and in the worst case… pinning the operator.
STEP 3 - CHECK THE LIMIT SWITCHES
Run the hook to the top, using slow speed (if applicable) as you reach the top just in case, and make sure the hook stops on its own. If it does, then your upper limits are good. Now run the hook down to the bottom, using slow speed (if applicable) near the bottom just in case, and make sure the hook stops on its own. If it does, then your lower limits are good.
NOTE* Not all hoists will have a lower limit or upper limit. It is important to know the specifics of your equipment when conducting these checks. If your hoist does not have a lower limit, do not bother taking it all the way to the bottom as that could damage the equipment. Certain chain hoists do not have an upper limit switch. These chain hoists may utilize a stop block on the chain or just the load block itself that works to stop the chain at the top. If this is the case with your hoist, skip this check because when the hook gets to the top it will just run through the load limit clutch and cause increased wear on a part that should never wear under normal operation.
STEP 4: CHECK WIRE ROPE/LOAD CHAIN
If your hoist has a wire rope, you will want to look for obvious visible damage such as kinks, broken wires, wires from the core sticking out between the strands on the outside, or significant gaps between the strands which allow you to see the core. If your hoist has load chain, you want to check for damage which may come in the form of grinder marks, bent links, twisted links, or corrosion. With a chain hoist, wear is a factor as well. Take your time to look for marks on the chain, thinning of the links where the chain contacts the sprocket or where the links rest against each other. One additional factor of concern with chain hoists having more than one "fall" (more than one length of chain coming down from the hoist.) Check for a twist in the chain; twists can develop if the load block gets rolled over between the falls. A twist in the chain can jam up in the hoist and has been known to break the chain, especially under load, so this should be corrected immediately if found. Remember there is no expectation to go up to the hoist itself to complete these checks -- simply check for what you can see from the floor.
STEP 5: CHECK THE LOAD BLOCK
Now let's bring the load block up to eye level and check that. Are there any cracks? Has a grinder run across it? Do the sheaves (pulleys) turn freely? Are there ruts worn into the saddle of the sheaves? Are the side cheeks moving around? Damaged? Is the hook twisted? Stretched? Does the safety latch come out the throat of the hook? Is there a significant groove worn into the saddle of the hook? If the answer to any of these questions is yes, please have the crane serviced immediately for your own safety.
STEP 6: CHECK THE LATERAL TRAVEL AXES
So far, so good? Good. Now that we are finally done with the hoist, time to check the lateral travel axes. Run your motorized trolley in low speed and high speed to make sure the circuit is working properly. If your crane has a single-speed trolley, a push/pull trolley, or no trolley, then don't worry about trying multiple speeds. Complete your trolley check by making sure the trolley moves well. Now stop the trolley. Did it brake well? Good. You need to make sure the brakes work. Complete the same check with the bridge or jib. Again, the purpose of this check is to make sure all components of the crane are working as they should prior to operation.
If you have gotten this far without finding any problems, then congratulations, your crane is ready for use! Don't forget to fill in the inspection report… and get to work!
The Crane Tech