Bridge Crane

[Doozer]

I am probably going to regret this....
But...
If you watch my Doozer's Shop channel
you know I went to the scrap yard and
got some eye beams for a shop crane
project. They are 5" x 14" eye beams.
Not W-section, not welded. Hot rolled
eye beams. Anyhow I modeled up my
ideas in SolidWorks. The rails (turquois)
are 19 feet long and will be supported on
the ends by 5" x 1/4" square tube columns
on floor plates. The bridge is 24 feet.
The 5" flanges on the bridge are 7/16"
while the 5" flanges on the 19 foot
rail beams are 5/16" . Web sections
are 1/4" on both. More of a girder beam
than a load beam, but I calculated
1/4" deflection with a 6000 pound load.
Anyhow, the wheels I was going to make
from 5" bar stock, a good lathe project.
I was going to use 1"id X 2"od ball bearings
pressed into the wheels, but then I thought
of the bolt on flange bearings might be
handy to mount the 1" axles to the trolley
flanges. The (brown) trolley flanges are
3/8" steel. The (yellow) trolley is 36" long
and made from 3 pieces of 2x2x1/4" steel
tubing. Like trailer hitch material. The
reason I did not use 2x6" tube is because
if I stack 3 pieces of 2x2" tubing, I get so
much more wall thickness, because I am
using it in the "weak" direction, and all that
wall thickness make it very strong for
bending.
As you see, the main bridge beam (green)
is notched and the flanges made to continue
around the notch. This is to drop the
bridge down to save ceiling height. I have
a 12' door opening and 14' ceiling height
so it would be nice to keep this in the
confines of a 2' tall package. The (gray)
5" cee channel on top of the bridge is
extra reinforcement, to help keep the top
flange, which is in compression, from
side buckling.
Any thoughts? Both good and bad?

--Doozer

[Rich Carlstedt]

Doozer, I will take a look at it , but first want to say you need diagonal braces..at least on one end of the beam ( Then float the other end more or less)
Are you looking at a 3 ton load for normal work ?

Rich

[Doozer]

Yes, good call on the braces.
I was also thinking about running
a 1" shaft from once side of the
bridge to the other, 24' to drive
a set of rollers with a chain wheel
to move the bridge.
Probably 2 tons is what I would want.
Thinking of moving the G&L HBM, the
Rockford Planer, and the 17" Colchester
lathe into the high bay to be able to
load big work on them with the crane.
Right now, with these machines in my
9' machine room, I can not drive my
fork lift in there. Not for head room,
just it is packed too tight in there.
I have a light 500 load
beam for my big lathes chucks and to
put light items on the HBM, but I was
thinking to have these machines in
the high bay and build a crane would
be better if I ever get into heavy work.

-D

[George Bulliss]

Very similar to what we had at my last shop. It even had a notch that is almost identical to what you drew. The bridge was not driven, you had to tug it into location. It was easy enough to position and the only time I missed it being driven was when flipping large pieces. A little creativity with the slings and blocking got things flipped, so it wasn't a big deal and not having a driven bridge was a much simpler design.

[vectorwarbirds]

First I don't know but since Doozer proposed it I would like to know this: In construction of wood beams if you notch it you now only have the strength of the notch width negating the total width of the beam. So a 12" beam notched 2" now becomes a 10" beam. Does the same hold true here with the steel I-beam with the notched ends? Just curious.

[Doozer]

No.

-D

[Mcgyver]

We make a lot of bridge cranes, large and small, beam to double box girder. They all have end trucks with the wheels recessed into a piece of HSS or built up box which runs on flat bar stitched to the top of the crane way. Might be so the runway surface is easily replaced, might be for compactness and maybe to not have a long wheel. Of course there is more than one way to skin a cat, but when I saw your end truck design, I thought you might like a view a common commercial approach.

[Doozer]

I knew McGyver would chime in.
Thank you.

-Doozer

[Rich Carlstedt]

This is funny in a way, there are two threads running that are related in a way.
One is on a Bridgeport Column door and this one....Whats in common ?
Chips.. in the BP thread , folks wonder how chips get/got inside a Milling machine Column.
In Doozers thread , it was pointed out that some bridge cranes have track rails and do not roll on the beams flange .
Well the rail is to eliminate "dirt/chips" from impeding the bridge crane for rolling "freely"
Instead of a 5" wide "accumulator " of dirt, its only 1 " (ie ) and thus less chance.
I have seen angle iron inverted on top of I beams and the wheels were grooved accordingly , so tracking was excellent and no dirt to contend with.
And you used only two wheels instead of four ..
You put thousands on pounds of weight on a crane and then move it rolling with 5 inch wheels and the wheels hit a .060" chip ...major stop... and more concern
it may stress the crane more than designed --a real no-no--- clean rails is imperative
Rich

Edit
Mcgyver---great Pics !

[Doozer]

I think birds trying to make a nest might be more of a problem.
If I get metal chips 13 feet up in the air, I would be pretty proud
of myself. Fuk yeah ! ! !

-Doozer

[J Tiers]

Not certain which beam has the 1/4" deflection. I think it is the span and not the track. You want to watch out about deflection, because with a load on the crane, a deflection causes issues.

First, if you have the load off-center on the span when you lift it, the runner wants to roll downhill so the load may try to "take charge" and go to the point of max deflection. Then the defection increases as the load goes toward center, so the tendency to roll downhill is constantly increasing. Positive feedback.

Second, you have to push a heavy load "uphill" if there is significant deflection and you need to move it off-center.

The ultimate slope is 0.020" in 12", which is not too bad. I don;t know if that load would actually roll downhill at that sort of slope. It can be calculated.

First I don't know but since Doozer proposed it I would like to know this: In construction of wood beams if you notch it you now only have the strength of the notch width negating the total width of the beam. So a 12" beam notched 2" now becomes a 10" beam. Does the same hold true here with the steel I-beam with the notched ends? Just curious.

No, because at the end, the bending is least, and what is left to resist is almost pure shear. So you need shear area, but not so much depth. Doozer is a mechanical engineer, so you can figure he probably has that sorted out OK.

A lot of old bridge cranes had fish-bellied beams across, deepest in the middle, for just that reason.

[wierdscience]

Anyhow, the wheels I was going to make
from 5" bar stock, a good lathe project.
I was going to use 1"id X 2"od ball bearings
pressed into the wheels, but then I thought
of the bolt on flange bearings might be
handy to mount the 1" axles to the trolley
flanges.

--Doozer

The bearing inserts will carry the load just fine, however the grey iron housings won't. A trick I use to overcome that, is to use stainless flange bearings-

https://www.ebay.com/itm/27289816934...wAAOSwDdlaocRS

[vectorwarbirds]

No.

-D

Thanks!

[The Metal Butcher]

Doozer,

are you sure you need 36" of receiver tube? Compared to the ones that McGyver posted, with much larger section beams, they seem a little bit overkill and will add to the deflection.

For your bearings, are you cutting the 1" axle into the wheels, or drilling them for a thru axle? Based on what I remember you saying your drops were, I believe it's the latter?

[JoeLee]

Is this going to be motor driven or manually pulled along?

JL..........