Bridge Crane designs and ideas...38' span

[countrybumpkin]

I've been really tossing the idea around to build or buy one for one bay in my new shop , would be 15' wide and 30' long. I don't need one near as heavy as most of the ones here a 2000 lbs would be way more than enough.

 

[Tractor Seabee]

Trying to plan out and decide how I want to build my bridge crane in the shop.

I cannot afford a new beam big enough for the 38' span. So will wait til the right one comes along on craigslist or whatever. There are some good ones on there now so I though I'd run some ideas by the board.

My main concern is with a 38' span, its gonna take a HEAVY beam, or a TALL beam, or a combination of both.

The HEAVY beams in the 16-18" range would be nice if I could find one. My concern with a taller beam is hanging a load from the bottom, and in order to move it you are pushing and pulling on the chain "twisting" the beam possibly causing the top to buckle.

I have colums, beams, and track for the main bridge to run on. It will have 12' of run, the a push-trolley on the 38' span. According to my math, minimum beams needed for a 10k max load SF are
5:1 SF....................3:1 SF
W12x106...............w12x72
W14x99.................w14x61
W16x89.................W16x57
W18x86.................W18x55
W21x83.................W21x50
W24x68.................W24x55

Ill probably never ever lift 10k, but my chain hoist is a 5t

Current craigslist beam offerings are:
W24x104 39' long. Overkill and more than I want to spend @ $1250 but would get the job done for sure if I can get it up there.

W12x72....2 of these 25' long each. Good price. $600 for both. Could be welded together, but under the 5:1 SF most cranes are designed for. Could take the extra 12' and weld to the top in the middle to gain some strength and bridge over the seam of splicing them together.

W24x84 38' long. Will easily handle the load and be easier to lift than the W24x104, but is about 3x weaker in the horizontal direction, and cost just as much. So for the price, I'd rather get the heavier beam and worry about setting it.

S12x35....30' long but he has 7 of them. I dont normally like S-type beams for long spans as they are too narrow and easier to twist or deflect in the horizontal direction with a single beam span and no flooring or nothing tying in multiple beams. But I have a crazy idea about attaching 3 of them together. Look at the picture for a cross-section:

View attachment 442848

Being two wide would solve the problem of S-type beams being weak in that direction. The bottom beam to gain depth would "probably" get the strength I need, but cannot find any formulas for stacking beams. The bottom beam would actually be about 1' shorter on each end, as the top two beams would extend and set on the "truck" that is riding on the rail.

My gut says this would be a sufficient setup, as overall depth would be 24" and plenty heavy. But the best part is this would cost me under $500 , and I could set them in place a beam at a time

Thoughts, Opinions, Am I crazy?

I am not going to read the while thread as the whole thing is a pipe dream so will jump in now. Cranes, especially bridge cranes are not something for a DIY project. Design of both the crane mechanism and the supporting structure are an engineering task undertaken only by engineers that specialize in cranes; as, the liability can be huge from a minor slip of the slip stick. If you are going to be the only user then the life you jeopardize is your own; however, if you have hired help your State Safety Inspector/Liability Insurance Inspector will shut you down in a heart beat; when you cannot produce an engineered design, the engineers certification after construction, and the latest annual inspection/load test report.

Have a casualty involving the crane, a by-stander, a helper, or hired hand; the lawyers and the injured/killed will own every thing you have. Over building does not get you off the hook. Word to the wise!!

Ron

 

[Arc weld]

I think you'd have to have some kind of welding credentials and it would need to be inspected. Shield Arc built his bridge crane but he had the assistance of an experienced engineer and he's been welding for a few weeks. A 10,000lb overhead lifting device isn't something to experiment with and hope for the best. Can some people design and build their own, sure but there's usually an engineer involved to check things over.

 

[LD1]

Relax safety police.

This is my own personal shop and no one for hire will be using the crane. No need for inspections or eng. stamp

Whatever beam I go with, I will run the calculations and assign a SWL. Dont need a freakin engineer to do some simple math for me.

 

[Shield Arc]

he's been welding for a few weeks.

Yeah but I'm a quick learner.
The beams I used for my span beam, were a spreader bar for setting pre-cast concrete utility vaults for the Pier D aircraft carrier pier in the local Navy ship yard. I told Mike I would have to splice the two beams right in the center. I ask if he was going to have a problem with that. He replied "if you can't handle that, we're going to have a long talk"!

 

[Streetcar]

Relax safety police.

This is my own personal shop and no one for hire will be using the crane. No need for inspections or eng. stamp

Whatever beam I go with, I will run the calculations and assign a SWL. Dont need a freakin engineer to do some simple math for me.

An engineer will tell you the safe working loads . Using your simplified calculation you need a large factor of safety.

 

[Streetcar]

Relax safety police.

This is my own personal shop and no one for hire will be using the crane. No need for inspections or eng. stamp

Whatever beam I go with, I will run the calculations and assign a SWL. Dont need a freakin engineer to do some simple math for me.

An engineer will tell you the safe working loads . Using your simplified calculation you need a large factor of safety.

 

[LD1]

An engineer will tell you the safe working loads . Using your simplified calculation you need a large factor of safety.

5:1 safety factor. What Im going off of.

Its not a simplified calculation. Its THE calculation for beam stresses and defletion. What else is there to calculate? ITs impossible to calculate an unknown amount of dynamic forces. THUS the safety factor.

Using my "simplified" calculations as you call them, my numbers match up very well with:

http://www.harringtonhoists.com/tech_support/edocs/EDOC 0367 rev02.pdf
https://www.cmworks.com/Public/11822/Crane Bridge Kits thru 5 Ton- 113535-27.pdf

So I dont see what the problem is. Whatever beam I use, I can calculate a SWL based on 5:1 SF. Or I can just use the sizing charts I listed.

IE:
W14x34 for 1-ton cap @ 40' span
W18x60 for 2-ton
W18x71 for 3-ton
Etc, etc

Problem is the charts list a single beam for each weight cap. Those specific sizes are not always available in the used market. All I am doing is recalculating for maybe a shorter but heavier beam, or taller and lighter. Since those "charts" dont list every possible beam that will work. One would be foolish to think that ONLY the beam listed can meet the rated capacity.

 

[FarmWrench]

Im lost. Not sure what you are trying to say.

A bridge crane requires THREE beams.

Two side beams, and the bridge beam that the hoist goes on.

I have a 38' span and a 12' span. The 38' direction is the width of the shop. The 12' span is along the outer walls.

Rather than span 38' TWICE, I would like to only span it once. On this beam, there will be a 5-on trolley and 5-ton chain-fall. The two beams that comprise the 12' run will be along the outer walls, and have 40#/yd rail on top, in which "trucks" will ride that carry the 38' bridge beam.

Not sure why some are suggesting to reverse the design, That would require TWO 38' beams instead of just ONE. And TWO beams spaning accrpss the width of the shop that are NOT movable. How does that help with anything. I would rather have a single 38' span beam, which would cost half as much as 2 beams, and have the ability to push it all the way to the back if needed for clearance reasons.

Wow. My idea was to keep your current design of non moving 12' rails with the matching trucks you have, but instead of an underhung hoist (load on the bottom flange of the beam) on one big beam, use a top running design (hoist rides on top of and between two smaller beams).
The two beams do not move in relation to each other. Think IOI instead of a big I with an O hanging under it.


This design also leaves the bottom flanges of both beams available for smaller hoists for greater manipulation of a load. You can hang multiple hoists on a single beam but they are unable to bypass one another. With a main hoist on top and one on the bottom that can bypass the top, turning loads over becomes easier and safer.


This will help you by having smaller beams to lift into place. Two beams can have better torsional rigidity. Top running provides more room under the hook. A larger area of each beam is loaded.

 

[Shield Arc]

Shield Arc. What is supporting the ends of your side beams? From the picture they're just hanging in the air. I'm sure it's the picture angle.

farmer2009 I gave you bad information! The center posts are 8" x 8" x 1/2" wall square tubing. You know how many times a day I walk right by those posts? And forgot what size they are.