Bridge Crane (with cantilevers!)

[Muckin_Slusher]

Getting started on a bridge crane for my little shop.

Existing "ceiling" is 24 inch tall I-beams embedded in the concrete floor above. 9'6" to the floor.

Yes I know they weren't designed or intended to be hoisting members.
Yes I know I'm gonna die.

Building was an apartment until it burned down. Now my shop is in the rubble leftovers.

This is how it was when I bought the building, picture from unloading a milling machine. I added the trees during this lift because I was chicken shit and also to reduce chance of hurting the concrete above.

You can see that the previous owner installed a wooden ceiling and insulation after the apartments above burned down.
You can see the OSB is level with the bottom of the i-beams, preventing their use for hoisting (stupid).

I want to fix that.

 

[Muckin_Slusher]

Potato-CAD drawing of what I'd like to build.

Want a 3 axis crane. Want 3 thousand lbs capacity.

See existing I-beams in ceiling (black).

Lift OSB/lumber ceiling up to expose two beams (brown and pink for fiberglass insulation).

Bridge I-beam shown in grey,, bridge trucks are orange.

Bridge trucks will have to accommodate downwards and upwards force because cantilever, so they will need wheels above and bearings below.
The existing I-beams are at least 1 inch out of parallel, so will have to account for that.

 

[Muckin_Slusher]

Thinking the bridge trucks will be made from four 1 ton trolleys (two at each end).

I remember using a bridge crane somewhere that had special trucks somehow that allowed the bridge to rack quite a bit before rolling. It was really nice because it was super easy to get the bridge rolling as only one end would move until the bridge ran out of slop, then the other end would move. If I can figure out how those trucks were made I could copy them, but haven't found that info yet.

Other option would be to have one truck floating (allow bridge to slide through) and have extra sideways wheels on other truck to keep bridge perpendicular.

Much appreciate any input on these topics.

 

[Muckin_Slusher]

Existing I-beams also have a second bottom flange hot riveted on. I believe this was to increase tension strength in the bottom flange.

These stupid rivets are in the way of standard trolleys.

I think my options would be to modify the trolley wheels to clear, or grind off the side of the rivet to clear, or add a piece of metal for the trolleys to ride on. I believe adding the piece of metal (3/4 inch solid square) would work best and make the most sense.

The wheels would then ride higher and clear the rivets and I haven't reduced the strength of any components.

Should I use hot rolled or cold rolled?

 

[Muckin_Slusher]

So far I've used the top of the forklift mast to start lifting the center ceiling section to expose the beams.
Need to rework the gas pipe, duct work, garage door track and some wiring.

 

[ThePanzerFuhrer]

9’6” is gonna be tough. Your max hook height is gonna only be maybe 7’-7’6”. Add some rigging in there and you’re not picking stuff far off the ground.

Make sure you are making everything as tight as possible.

My crane has a 22’ hook height and I’m forever running out of height

A rotating jib with a trolley that goes between two facing c channels for the jib would allow you to get the hoist as far up as possible to give you the most pick height.

 

[PAToyota]

I agree on the pick height being an issue, but your picture of the milling machine shows there would still be stuff you could do with it.

I'd be a bit concerned on the cantilever. Just a bridge between the two existing beams obviously can put most/all of the load on one beam depending on where you are. With the cantilevers, you're getting into rotational forces and how those act on the riveted beam may be a question. Just the fact that you have a hot riveted beam raises some caution flags for me - you know from its age and condition after the fire there are some questions there. If you were just pulling engines and stuff I'd say have at it. A ton and a half and I'm a bit more cautious with jury-rigging stuff connected to the main building structure.

How much weight was the milling machine? And, of course, you had the beam braced for that. Are you bracing the beams outside the run of the crane? Or how much unsupported span are you talking about?

I try to look at failure modes. If something would either cause the beam to start separating from the concrete or that plate to start separating from the beam, things could progress rapidly as opposed to just "that beam is deflecting more than I feel comfortable with, maybe we should stop and rethink this."

 

[arse_sidewards]

I like your plan. I think the trolleys will just clear as is but I think that the 3/4 stock plan is a perfectly good back up if they don't.

Pick height won't be an issue for you since you already work in that space just fine. I have like 7ft under the traveler and 6ft under the hook and it's fucking awesome.

One thing I did on mine was give the traveler a few degrees of tilt so that you're not side loading the trolley if you run the traveling all the way to the stops and then pick something that's a couple feet beyond.

 

[Muckin_Slusher]

I agree on the pick height being an issue, but your picture of the milling machine shows there would still be stuff you could do with it.

I'd be a bit concerned on the cantilever. Just a bridge between the two existing beams obviously can put most/all of the load on one beam depending on where you are. With the cantilevers, you're getting into rotational forces and how those act on the riveted beam may be a question. Just the fact that you have a hot riveted beam raises some caution flags for me - you know from its age and condition after the fire there are some questions there. If you were just pulling engines and stuff I'd say have at it. A ton and a half and I'm a bit more cautious with jury-rigging stuff connected to the main building structure.

How much weight was the milling machine? And, of course, you had the beam braced for that. Are you bracing the beams outside the run of the crane? Or how much unsupported span are you talking about?

I try to look at failure modes. If something would either cause the beam to start separating from the concrete or that plate to start separating from the beam, things could progress rapidly as opposed to just "that beam is deflecting more than I feel comfortable with, maybe we should stop and rethink this."

I appreciate the response.

They aren't riveted I-beams (I mean they're not 7 piece beams like what might be in the ). Seems hot rivets stopped being used as late as 1960s. I'm not sure the original date from when my building was built, but my house which is on the same street was built in 1937.

They are modern one-piece I-beams with an extra flatbar hot riveted on the bottom for extra tension resistance, so they're beefed up beams.

I don't see any change in those beams from the fire. They still have the original paint on them. The fire happened on the upper floors.

Milling machine was 8000 lbs or less (guess). I braced the beams out of an abundance of caution. Didn't cost much in time or materials.

I'm not bracing the beams outside the runs. The ends of those existing beams, and the tops of those beams are encased in poured concrete. I'm 100% sure those beams won't even know they're being pulled on. The cantilevered section of the bride will be half the distance beam to beam.

Unsupported span? Well it's 8 feet on center for the existing beams, and they're 24 inches tall. Currently they're spanning 24 feet and have the tops encased in concrete as part of the upper floor, which seems to be in perfect condition. I really feel that 3 or 4 thousand lbs isn't even a blip on what this structure can support.

99% of the use of this thing will be small lifts, like snowmobile and atv stuff. If for some reason I'm picking up one end of my truck I'll be making sure it's between beams.

I'm figuring on making all the hardware rated for 4000 lbs, giving the thing a 3000 lbs rating and then using it for less than 1000 lbs 99% of the time.

As for the height, well, you've got to piss with the cock you've got. I'm not raising the ceiling. This whole thing will just be for convenience. If I get into bigger/heavier/taller stuff I've still got the rest of the warehouse to work in (14 feet to truss bottoms) and eventually I'm planning on a 20 foot ceiling in front of the little shop to accommodate a vehicle hoist. It has to at least be better than nothing.

Anybody got a guess on what lbs/foot 6 inch beam I should be shopping for? I'd guess a 4 inch beam would probably be enough, but I don't think 2 ton trolleys would even fit on a 4 inch beam, so it'll be 6 inch.

 

[Muckin_Slusher]

Just for fun, this was my original post from pirate back when I was toying with building a trolley between beams to give the most hook height possible.

 

[arse_sidewards]

For the traveler W6 by 9lb is more than enough beam for what you're doing.

Somewhere is a thread I started about beam calcs using 24", 55LB/ft I-beams. Your spans are on the same order. This could be a 10-ton crane without affecting the above floors if you wanted it to be (you'd need more than a W6 traveler though).

You could double up on the travelers and have the trolley riding above them with the hook between if you want more height.

 

[PAToyota]

Unsupported span? Well it's 8 feet on center for the existing beams, and they're 24 inches tall. Currently they're spanning 24 feet and have the tops encased in concrete as part of the upper floor, which seems to be in perfect condition. I really feel that 3 or 4 thousand lbs isn't even a blip on what this structure can support.

Ok, that sounds a lot better. I realized it was just the plate riveted to the beam - not a fabricated beam - but it's still been awhile since anyone was hot riveting much of anything.

Anybody got a guess on what lbs/foot 6 inch beam I should be shopping for? I'd guess a 4 inch beam would probably be enough, but I don't think 2 ton trolleys would even fit on a 4 inch beam, so it'll be 6 inch.

Something like this - WebStructural - Free Steel Beam Design - will let you play with loads and beam sizes to get an idea. It's not going to do the cantilever, though.

 

[Muckin_Slusher]

9’6” is gonna be tough. Your max hook height is gonna only be maybe 7’-7’6”. Add some rigging in there and you’re not picking stuff far off the ground.

Make sure you are making everything as tight as possible.

My crane has a 22’ hook height and I’m forever running out of height

A rotating jib with a trolley that goes between two facing c channels for the jib would allow you to get the hoist as far up as possible to give you the most pick height.

Homemade low profile hoist from sideways chainhoist using the funny square chain pulley salvaged from a 2:1 chain block (square pulley would go where red circle is)? That would be the smallest diameter pulley, giving highest hook height without going double bridges. Also I drew it wrong, hook should be centered between the blue rollers, but you get the idea.

I would probably need to add extra wheels underneath to prevent rocking.


A friend has this oddball 120 volt electric hoist that uses roller chain and would be perfect for this application. Pretty sure it's 1 ton rating.

 

[Muckin_Slusher]

Made some progress, removed some duct work and redid the garage door track to shorten it and the supports. Pushed up most of the ceiling in the middles. I think the ends are nailed to the walls so will have to deal with that.

Installed a couple of 1 ton Princess Auto trolleys. I had to leave them "looser" than they should be on the beams to clear the rivets. They move nicely when unloaded but kind of bump along.

Most likely this is how things will be for the winter.

Feel stupid, should have done this years ago.

 

[GLTHFJ60]

Fuckin love it.

Cantilever could work in my potato brain, but it wouldn't be movable with a load on the cantilever end. The far trolley would be forced up lifting the wheels off the flange.

 

[IowaOffRoad]

Fuckin love it.

Cantilever could work in my potato brain, but it wouldn't be movable with a load on the cantilever end. The far trolley would be forced up lifting the wheels off the flange.

Came here to post the last part. We have some fabbed cantilever bridge cranes here and they do exactly as you described. The other issue with the home fab bridge cranes is the trolleys really can't be tightened up on the beam enough to let the beam roll when loaded heavy on the outside third from the centerline between the top beams.

 

[Muckin_Slusher]

Got pics?

Lets fix the problem. I was planning on making the trucks adjustable (shims and/or push bolts, etc).
Was also planning on bottom bearings so they can still roll when the cantilever is loaded.

IowaOffRoad----can you post pics of your cranes?

 

[Muckin_Slusher]

I guess I never labelled or mentioned it, but in my first paint drawing this is what I meant:

 

[GLTHFJ60]

I guess I never labelled or mentioned it, but in my first paint drawing this is what I meant:

That would work. So would another set of trolley casters on the bottom sides of the beams. Could place them on the outsides of the traveling beam if you made the trolley plates longer.

 

[IowaOffRoad]

I guess I never labelled or mentioned it, but in my first paint drawing this is what I meant:

We don’t have an under roller, though the reason it gets cocked and bound while loaded off-center is the same reason why your roof rack crossmembers require two people to move or you run back and forth, or why your worn-out bench seat doesn’t slide back and forth well

 

[IowaOffRoad]

.

IowaOffRoad----can you post pics of your cranes?

if I remember tomorrow I will.

 

[Muckin_Slusher]

Been reading about pulley and cable systems to keep the bridge perpendicular to the rails.

Found this post showing a driveshaft on top of the bridge with roller chain gears at each end. Forces the bridge to stay perpendicular.

 

[arse_sidewards]

Been reading about pulley and cable systems to keep the bridge perpendicular to the rails.

Found this post showing a driveshaft on top of the bridge with roller chain gears at each end. Forces the bridge to stay perpendicular.

I don't get how that works but I could really use that on mine.

 

[ThePanzerFuhrer]

I don't get how that works but I could really use that on mine.

One sprocket on each end of the shaft near the trucks. If both sprockets are engaged in a chain it does not allow the gantry to rack. It must stay straight as it moves.

 

[arse_sidewards]

So the chain is static like a rack gear?

 

[ThePanzerFuhrer]

So the chain is static like a rack gear?

Yes

 

[PAE]

Here this should help in your bridge design.

Dont ever say I dont contribute to engineering threads here.

 

[IowaOffRoad]

Got pics?

Lets fix the problem. I was planning on making the trucks adjustable (shims and/or push bolts, etc).
Was also planning on bottom bearings so they can still roll when the cantilever is loaded.

IowaOffRoad----can you post pics of your cranes?

Sorry it took so long and sorry the pics aren’t better. This is in a test cell am I can only show so much, but you get the idea

 

[Muckin_Slusher]

Sorry it took so long and sorry the pics aren’t better. This is in a test cell am I can only show so much, but you get the idea

Thanks,

Those look like W beams. Seems like S beams (with the tapered flange) help to self align the trolleys to the middle. Unfortunately my beams are also W beams. My beams being so close together (8 feet) might help the bridge resist racking. Seems to me that the further apart the runways, the more tendency to rack. I can always add side bearings to one trolley and have the other trolley floating to accommodate out of parallel.

I've searched through a million threads online and everyone wants the same information, "what size beam do I need?"

Would be pretty cool to have a monster thread somewhere with info on existing installations:

What beam is used (height/type/weight)
Span
Load rating

Every thread seems to get the same generic answer---call an engineer.

In my case I guess a 6 inch S-beam 12.5 lbs/foot would work for a 2 ton rating.
If I was to go with 2 beams could I use 4 inch 9.5 lbs/foot?

 

[IowaOffRoad]

Thanks,

Those look like W beams. Seems like S beams (with the tapered flange) help to self align the trolleys to the middle. Unfortunately my beams are also W beams. My beams being so close together (8 feet) might help the bridge resist racking. Seems to me that the further apart the runways, the more tendency to rack. I can always add side bearings to one trolley and have the other trolley floating to accommodate out of parallel.

I've searched through a million threads online and everyone wants the same information, "what size beam do I need?"

Would be pretty cool to have a monster thread somewhere with info on existing installations:

What beam is used (height/type/weight)
Span
Load rating

Every thread seems to get the same generic answer---call an engineer.

In my case I guess a 6 inch S-beam 12.5 lbs/foot would work for a 2 ton rating.
If I was to go with 2 beams could I use 4 inch 9.5 lbs/foot?

We have an assortment of homemade bridges around here, both styles of beam. With the Chink trolleys we've used they act the same way. I imagine if you had a beam with the same taper as a train rail you may get self-alignment. Maybe a better trolley would work better too.