Last week there was a serious incident concerning a new bridge crane on a refinery project my previous employer is managing. A new Total Tool bridge crane had been installed and was being connected and checked out by a factory technician. A manlift was working about 2 ft away. At some point the tech did something and the crane moved and kept going. He hit the emergency stop to no avail. The bridge crane traveled into the manlift crushing the tech against the man lift. An alert electrician working in the area on the ground seem what was happening and ran 80 ft shutting off a main to stop the unit. The JlG man basket was still intact. The crane tech somehow got tangled up between the handrails it was equipped with and the JLG and suffered broken ribs and has bleeding around his liver. Fortunately he is expected to recover. The last 4 days the unit has been under investigation by the refinery, the contractor, the crane manufacture, and the authorities. The crane was found to be wired correctly by the electrical contractor to the machine. Sunday( yesterday) all bridge cranes from this manufacturer were ordered to be shut down until they can be inspected. Starting to sound like an internal issue in the machines although no official report is out yet. If using one of these if nothing else check your Emergency Stop each day to insure it is working.
Gotta love modern technology. Hope the tech recovers okay, horrible deal.
Glade the bridge crane we had at the shop where I worked was a recycled one originally built in the 1920's! Every inspector who has been out to inspect it says to take care of it as you don't want what they sell as a 40 ton crane these days! Best of luck to the tech!
Theres only 1 positive 2 this, his damaged liver will work 1/7th instead of 1/8th. full function.
Got an update today. The crane was built by R & M. They are installed by Total Tool. I do not know whom installs the controls. As is usually the case there was a number of things that perfectly lined up in multiple failures to cause the accident. It turns out the controls were not wired per the schematics for the machine. The bridge crane is 35 ft above the floor. The tech weighs in at the 350 lbs range. A manlift was used to hoist him to the handrailed platform. Another worker was in the manlift as the crane tech did not have an ariel lift certificate. The bottom of the zoom boom manlift basket was placed at the top of the rail and the tech using 100% tie off descended onto the handrailed bridge crane top platform. He pulled the control cable up and started his checkout. The winch went up and down. The winch trollied left and right. Next he moved the bridge crane. It was about 2 feet from the wall. It moved toward the wall. He bumped it the other way and it started off. He let go of the button and it kept going. He hit the emergency stop and it kept going. He flipped the disconnect and it clicked but the crane kept going. It hit the manlift and was lifting the boom of the man lift. The wheels were off the ground more than a foot when the electrician on the ground got the main shut off. The investagation discovered that the control buttons were not wired per the schematic. There was a button that would have de-energized it but he never got lucky and hit that one. It was not the red emergency stop one. The emergency stop energized another function. To top it off the mechanical knife disconnect on the crane failed. When the tech pulled that disconnect lever down the click they heard was the lever breaking inside the cover leaving the blades connected energizing the unit. On the inside it looked like it was built by a 4 year old using tin foil parts instead of the quality one would expect. It will be interesting to see the fallout from this.
As to the disconnect switch: some of these switches are required to be 'motor rated'. The catalog [for the ones we purchase] doesnt have it in the specs, but it is labeled on the inside of the door of the disconnect. The going idea is the motor rated ones are heavier duty, but when ordering it would be nice to know which mfg and type to select. * Handles have broken on these as well but luckily for us we were doing some other work: not trying to terminate an emergency. Wonder if the type with a rocker lever would be better as it is probable and possible the lever style allows the human (knowingly or unknowingly) to move the lever in an imprecise motion thereby placing a bending moment on the operating shaft?
Sounds Scary, Machines are machines, they are not Humans so, I think it's our duty to check the machines at first before start working.