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  1. #1
    Join Date
    Aug 2004
    Location
    Milan Michigan
    Posts
    1,671

    Default Frame repair on Crane truck

    I have a HD straight truck that has tandem drive axles and 3 lift axles 5 axles total on the rear, This is a log truck and because he also pulls a trailer they mounted the Prentice crane on the very back of the truck so they can unload the truck and trailer with the same crane.

    The frame has been repaired 2 other times, I want this time to be the last. It currently is broke in 3 different areas.

    The 2 breaks are right over the back tag axle right where they stopped the 1/2" plate that they used to box out the frame, which is about 16" in front of where the crane mounts.

    It also broke on one side up farther where the welded across the frame Which is a big no no, They didn't even have enough common sense to do a oval patch on the side of the frame.

    What I'm going to do is make a new channel out of 1/2 plate that is 15' 6" long and start at the very back and run it up front and put all new bolts in. This will require me to unbolt the crane, lift it up enough to slip the new channel and put back together.

    It will also require me to widen the tag axle 1" wider, because where it bolted to the frame it was rotted any way so I had to rebuild the mounts any way.

    We have already vee grooved the cracks and welded the 3 broken areas.

    The new channel will run about 14" past the front crack.

    I don't plan on welding the new channel, there are approximately 38 bolts on each side that will hold it in place, not to mention the 8 bolts on the crane that are about 1-1/2" diameter.
    I also plan on painting the outside of the old channel and the inside of the new to prolong the rust as long as possible.

    Does any one have any precautionary suggestions that I did not mention, other than going up farther because the two front tag axle mounts also need to be rebuilt but they don't have any money for that.

  2. #2
    Join Date
    Aug 2004
    Location
    Milan Michigan
    Posts
    1,671

    Default

    I also forgot to mention, When I built my shop I cast six 14" tall beams into the floor that are 31' long with 4 other beams running across to tie everything together, I then welded 1" nuts on the bottom side of the top flange prior to pouring the concrete so I can screw 1" eye bolts into the beams, I have 72 tie down points, Two of the beams run parallel with the frame of the truck, two more are 8'-6" on center to catch the out side edge and the other 2 are 15' apart.

    So before I did any welding I leveled out the frame on the beams.

  3. #3
    Join Date
    Mar 2012
    Posts
    27

    Default

    Post a couple pics will probably help. I had a crane truck with a serco 8000 and had a similar problem. We just put another c channel inside the current frame and ran it from the back to the drive tandems and boxed it in.

  4. #4
    Join Date
    Aug 2004
    Location
    Milan Michigan
    Posts
    1,671

    Default

    Okay, Not much for responses, If it breaks again I'm holding all of you responsible.

  5. #5
    Join Date
    Apr 2009
    Location
    Oswego IL
    Posts
    590

    Default frame....

    Quote Originally Posted by Portable Welder View Post
    Okay, Not much for responses, If it breaks again I'm holding all of you responsible.
    I will put my two cents on this. I have seen many frames which have cracked, couple of questions, is it a single frame, double frame, or possible triple frame, i have seen many cracks devlope because the frame can no longer flex, espically on logging roads, the more rigid the frame becomes the worse it breaks, no amount of gussets, will make the strength of a double frame where someone is trying to substute a single frame. I fixed a similiar rig where the frame has been streched on a osk kosh with a rear mounted knuckle boom, i had a section of frame bent to insert in the broken area, i cut out the broken area, sectioned in a frame section at the crossmember then bolted the sections together, that was 10 years ago and it has yet to break. Truck frames must twist together, also is the frame heat treated? I have a picture somewhere where a tool box was welded right over the do not weld on frame member sticker!
    Kevin
    XMT 304
    Miller Spectrum 625
    Miller 30a spool gun
    S22a
    Miller Legend 302
    Lincoln LN25
    Ford f450 Maintainer Srv Truck

  6. #6
    Join Date
    Sep 2009
    Location
    Canada
    Posts
    169

    Default

    Preheat to 150f / 65c to sweat it out and weld it with 7018
    Lincoln Idealarc 250 stick/tig
    Century Mig
    Thermal Dynamics Cutmaster 52
    Torchmate CNC table

    Owner/Operator Devlin Metal Works
    Custom CNC Plasma Cutting and Welding

  7. #7
    Join Date
    Aug 2012
    Location
    Hermiston Oregon
    Posts
    204

    Default

    I weld on truck frames all the time . No biggy if done correctly. Big no on 7018 more like 11018 . Heres a picture of a truck frame I extended a while back for a drop axle .

    For some reason it wont let me post more than one picture could the moderator fix this problem
    Attached Images Attached Images
    Last edited by eecervantes83; 02-26-2014 at 11:01 PM.
    .
    Miller Bobcat 225NT onan
    Millermatic 211
    Spoolmate 100
    (Retapped to fit regular mig tips)
    Work better & less parts to stock.
    Miller 130xp
    T/A Dragster 85 (portability 11 pounds)
    Oxygen/Acetylene torch set 50'
    2. 4-1/2" grinders
    1. 9" grinder
    14" Makita chop saw
    1/2" Aircat impact gun 900#

  8. #8
    Join Date
    Aug 2004
    Location
    Milan Michigan
    Posts
    1,671

    Default

    trygn5, The frame is currently a 2 member and I'm making it a 3 member, The inside is approximately 3/16" believe it or not.

    The outside is a 5/16" or so ( I didn't put a mic on it ) The new outside frame that I made is 1/2" plate press broke into a channel.

    Tryagn 5, I think you hit the nail on the head, when I'm done it still has to flex,
    ( If it cant flex then its gonna break. )

    I'm thinking that's why they put a channel in a channel verses making just one heavy channel. ( Kinda how a leaf spring works )

    __________________________________________________ ______________

    My next problem is, Since I removed the 8 threaded rods that are 1-1/4", they were really on there so we had to heat the nuts to remove and I found them to be corroded so I have to get new ones.

    I don't know what was on there but the guy sits on top of the crane as it swivels so I'm going to use a A354 BD rod with matching nuts and washers ( Which is basically a grade 8 that are rated for 150,000 psi. ) To be on the safe side.

  9. #9
    Join Date
    Aug 2004
    Location
    Milan Michigan
    Posts
    1,671

    Default

    I also went Browsing on the internet to verify what I think I know about welding Semi Truck frames.

    I ran across a post I made here,( years ago.)

    I ran across a bunch of Hogwash from people that really don't know anything.
    After reading through at least 50 different sites.

    I finally found a post from a guy Named Rick Weber from Versalift that truly knew what he was talking about.

    The article substantiated what I thought because I have reinforced beams and bar joists under the guidance from 100s of engineers over the years.

    Everything this guy said is on PAR with all the engineers I have delt with over the years.

    Some of the reading is a little technical if you don't understand certain terms you can easily get lost, but to dumb it down a bit, Its better if the load being applied is attached to the vertical section ( Which is called the web, whether we are talking in terms of a channel or a beam ) than being mounted to the flange, which could be the bottom or the top of the beam or channel.

    It also went on to say, When you add cross members you make the frame stiff, ( When you make it stiff you also make it more susceptible to cracks) Try to let the front of the frame under the cab stay flexible where it can twist, you can then make the backside where a hitch would be more rigid. ( But don't make both ends rigid.)

  10. #10
    Join Date
    Apr 2009
    Location
    Oswego IL
    Posts
    590

    Default exactly...

    Truck frames have to twist, having 3 sections of frame, is much stronger then a single frame ofnthe same thickness because ridgid and the stresses of constant vibration do not mix. Watchnan off road truck going down a rough road, the frame bends and twists with the road, thus it helps to absorb the impacts. Also i forgot to mention to pay close attention to the condtion of the suspension of the truck, if its shot, thats going to play a part in the failure. I have always followed these rules when fixing frames, when sectioning, always start at a cross member, i normally angle cut all frame sections, with the crossmember in the center of the splice, keep gussets and plates to the same thickness of the frame, always plug weld, add addtional cross members if needed, pay close attention to types of steel used, many over the road trucks, are single frame, high strength steel which are built to be light and thin, these trucks do not take sectioning well, simple fact they were never made to be turned into offroad trucks, and will fail if they are pushed off road.
    Kevin
    XMT 304
    Miller Spectrum 625
    Miller 30a spool gun
    S22a
    Miller Legend 302
    Lincoln LN25
    Ford f450 Maintainer Srv Truck

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