Crane bridge runway wheel position on track
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  1. #1
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    Default Crane bridge runway wheel position on track

    I just took delivery of all the steel to assemble the runway for my 5 ton 33' span bridge crane. The bridge and runway were built and installed by US Crane. Not homemade. Before I pour the foundations and start cutting steel to length I want to triple check all my dimensions. The runway itself is W14/43 with 1.5" square bar on top for the bridge wheels to roll on.

    The 4 bridge wheels have flanges on the inside and outside, but the rail contact area for the wheels is 2.5" wide. If I centered the 1.5" rails position under the wheels the bridge has an entire inch to move side-side. This seams too much to me. I'm thinking putting the rails each outboard 1/4" from center of the wheels on each side to give the bridge 1/2" total side-side play.

    Does this seem reasonable or should I center the rails under the wheels?

    I did not take the crane down. US crane doesn't have drawings.

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    Isn't your wheels on adjustable axles of some kind?
    ... Making the concern over where to place the rail "exactly" may not be of issue, as the wheel spacing can be edited quite a bit I would think. ???


    I'm guessin' that the extra play is to allow for some gee and haw of the rail over the length? But too much slop will allow the bridge to get cattywampous to some degree.

    If you wanted to take out some slop, could you just make new end caps that are counterbored a 1/2" each?


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    Think Snow Eh!
    Ox

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    all the cranes I have seen have the rails bolted to the beam,
    so the final alignment can be done after all the support steel
    in welded in place.

    As far as "walking" side to side, Ussually the wheels are driven by a drive shaft
    extending from one rail to the other, to keep the wheels in sync.

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    With a soft start - that prolly works good, but mine is kind'a rambunctious, and will doo smoky burnout's - allowing it to get out of sqr.


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    Ox

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    Quote Originally Posted by Ox View Post
    With a soft start - that prolly works good, but mine is kind'a rambunctious, and will doo smoky burnout's - allowing it to get out of sqr.


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    No sir, I used to drive a 5 ton top running, that went bang bang.
    Full blast or dead stop (and as soon as you let off the button, those
    brakes slammed right on pronto)

    And that's how you drove it...like your a kid playing a video game.

    I also drove the neighbors underslung 3 ton, now that had a drive on each side and no shaft. Sort of a soft start on that one.

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    Are the tracks truly flat? Most crane ways have a bit of taper towards the bridge, the inner flange is where the crane will run or close to it.

    Steve

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    Quote Originally Posted by Steve in SoCal View Post
    Are the tracks truly flat? Most crane ways have a bit of taper towards the bridge, the inner flange is where the crane will run or close to it.

    Steve
    Yes, that brings up a good point, the rails I have always seen are smaller versions of standard railroad track.

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    I only worked for a crane outfit for 11 months but the 1.5 bar track was standard. The wheels were centered on the track. What was really important was that the end trucks were square 90 degrees to the main beam. We would double/triple check by using fifty foot tapes crossed under the beam corner to corner before welding solid.
    No matter what, ground settles and foundations shift so you need some leeway for the track to shift over time. The worst I saw was a building situated on what had been peat bog years prior. One end of the building settled over a foot down. The crane brakes would not hold the bridge and it would roll on its own to the far end of the shop. The crane track had to be bolstered and aligned on a Saturday.
    At lunch time for a laugh a guy lit a paper town then threw it onto one of the cracks in the floor. You could see a blue flame travel along the crack.

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    Quote Originally Posted by digger doug View Post
    all the cranes I have seen have the rails bolted to the beam,
    so the final alignment can be done after all the support steel
    in welded in place.

    As far as "walking" side to side, Ussually the wheels are driven by a drive shaft
    extending from one rail to the other, to keep the wheels in sync.
    Most of the older cranes I have seen use railroad rail and tapered wheels, but seems to me like cranes built 1970's and newer use the square bar more often than not. The 1.5" bar on mine is welded to the top of the W14 beams, but the beams are bolted to pads on the uprights. I hope I can shim things pretty close after welding all the support structure solid.

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    Quote Originally Posted by Steve in SoCal View Post
    Are the tracks truly flat? Most crane ways have a bit of taper towards the bridge, the inner flange is where the crane will run or close to it.

    Steve
    Steve, The tracks and the wheels are flat. Mine looks a lot like this bridge for sale on Ebay: Shannahan 5 Ton 35' Top Running Underslung Bridge crane | eBay You can see some close up pictures of the wheels in that auction.

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    So much for my sage advice! I saw another pic on ebay that shows the wheels in great detail. Patent track and rail were the two I was aware of, add this to the old memory banks. How long is the runway?

    Steve

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    Two things . . .

    I'd put a VFD on the bridge motors. Washington Crane certified our crane installation and they were surprised at how well our crane was controlled. A single VFD on two motors and our crane has never once skewed in going on 8 years of use and abuse. We used Control-Techniques UniDrives that were easily configured to manage the brakes. Set up for creep speed with linear accel/decel, and high speed with S-curve accel/decel . . . makes for excellent all around high speed yet precise positioning duty. We put VFDs on the hoist and trolley as well, but putting one on the bridge made the biggest improvement over behavior and performance of the original wheel spinning across the line contactors.

    I would check with the manufacturer of the crane on wheel placement. I am getting ready to order two new cranes and they will run on standard A.S.C.E. crane rail. I had not seen the square rail, and the two new cranes have similar wheels with just the slightest taper, but run on standard crane rail.

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    it does not seem right to me
    systems I have dealt with had secondary followers for the side of the rail

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