Crane for lifting heavy equipment

OldCarGuy said:
Here's one of my present examples in my 30' by 50' home shop that I built over 20 years ago. As you can see it has a capacity of 4,000 pounds with a nine foot hook height off the floor.
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I'm no expert but aren't those beams a bit narrow for the length?

Back when I was researching on the topic I realized the importance of the safety factor. If you want to lift 1 ton you don't use 1 ton rated beams. You use 5 ton beams...
 
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m1kemex said:
I'm no expert but aren't those beams a bit narrow for the length?

Back when I was researching on the topic I realized the importance of the safety factor. If you want to lift 1 ton you don't use 1 ton rated beams. You use 5 ton beams...
Click to expand...
It depends on the design and weight of the side beams. The beams along the sides look like 10" wide-flanges in the picture, maybe 24' long. The lightest 10" wide-flange is 15 pounds per foot, and with a 4000-pound load (such as with a fully loaded hoist at one end of the bridge) centered in that 24' span, plus the dead load of the beam, the deflection (sag in the center) would be about 3". I didn't calculate the stress, but that deflection would, of course, be unacceptable. A 10" wide-flange can be as heavy as 115 pounds per foot, and with the same calculation results in a center sag of about 3/16"--probably okay. But this isn't a W10x115--that beam section has 1-1/4" flange thickness and these beams are clearly not that heavy.

With long and slender structural elements in bending, deflection is usually the controlling characteristic more than stress.

I'm sure an installation like this came with a PE-stamped design, however. But the side beams may have different ratings than the bridge itself, and the designer may have derated the bridge capacity. That should be a note on the plans.

Rick "a civil engineer but not doing this officially" Denney
 
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m1kemex said:
I'm no expert but aren't those beams a bit narrow for the length?

Back when I was researching on the topic I realized the importance of the safety factor. If you want to lift 1 ton you don't use 1 ton rated beams. You use 5 ton beams...
Click to expand...
Incredible shop. I feel the same as for the choice of beam height and capacity. The aisles suggest the trolley is to move work from one machine to another and may never overload the structure. Moving a machine is another story. If nothing else I would support the stationary horizontal beams with a vertical beam in the center on both sides ( mid span ) of the trolley if the owner doesn't doesn't already do so when lifting at full capacity even temporally.
 
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Charles scozzari said:
Incredible shop. I feel the same as for the choice of beam height and capacity. The aisles suggest the trolley is to move work from one machine to another and may never overload the structure. Moving a machine is another story. If nothing else I would support the stationary horizontal beams with a vertical beam in the center on both sides ( mid span ) of the trolley if the owner doesn't doesn't already do so when lifting at full capacity even temporally.
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In the end, it’s the results that count. I've been using this bridge crane for nearly 25 years. And has lifted many objects around the shop. Plus all of my machines,, more than once. My Deckel was 6,000 pounds. And I'm still here to write about it.

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@OldCarGuy your bridge, is a commercial one, isn't it? It looks like a 6X10"wide flange beam, at 24' span, about right for a rating of 4,000 lbs.
 
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The bridge beam is 14” with 5” flange and the runway beams are 12” with 4” flanges. Since both the trolley and end trucks are non motorized the crane is self centering over the load. Making side thrush a minimum.
 
Charles scozzari said:
The load isn't always centered
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It's been my experience when the hoist is not directly over the load and the chain at an angle, when the hook is raised. Either the hoist trolley and bridge beam with move directly above the load. Or the load will be dragged across the floor enough to be directly underneath the hoist. Depending if the load is heavier than the resistance of the crane. That's when the trolley and end trucks are non-motorized. As my setup is.

A newer bridge crane feature senses when the chain at an angle between the hoist and load. The hoist will automatically position the hoist directly over the load. Soft start and stop is another great feature that's been around for years. With a load on the hook, The trolley and end trucks start off slow before picking up speed. And wil lslowly come to a halt. So the load will not swing.. I always spec those features in the plants I've designed.
 
What I was pointing out is that with a capacity load, or a 6.000 lb machine at the center of the ( blue ) beams span and the trolley ( yellow ) beam to its extreme left or right may tax the horizontal beam. But you're right its been working for 25 years without any problem so life go's on. Thanks.
 
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