A Frame or Gantry Lift

   / A Frame or Gantry Lift #1  

bal0123

Bronze Member
Joined
Aug 24, 2008
Messages
62
Location
Purcell, Oklahoma the middle of no where
Tractor
Yanmar 2210, and 2, 425 John deere lawn tractors
So I just finished my A-Frame. I bought a cherry picker about a yr. ago and did not like it. Cause the supporting legs to the front of it are about the same width as lawn tractor wheels. That makes it hard to get underneath the tractor and be able to lift straight up. Since most of my work is lite, but still heavy when pulling lawn tractor engines. I needed something that would help assist in removing the engines or whatever else I needed to do. So here it is. I used mostly scrap metal I had laying around. I did use the front supporting legs off the cherry picker and had to buy a top beam. Man the price of metal is out of site. Twenty foot stick is the only way they sell metal around these parts. I used a 2"X6"X11ga. retangular tubing for the top beam. I was going to use a 3"X5" I-Beam but they wanted 200 dollars for that so I settled for the rectangular tubing instead for only 92 dollars. It seems to work great, as you can see from the trecher I just purchased. It ways prolly around 600 - 800 lbs. and is about 2 feet off the ground supported by the A-Frame. Hope yall like.
 

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   / A Frame or Gantry Lift #2  
Some ones going to get hurt with that thing, like the photos in background tho!!
 
   / A Frame or Gantry Lift #4  
I hate to slam on your work that you are obviously proud of, but IMO, that looks like an accident waiting to happen. The cross beam looks adequate, but 11Ga wall thickness may be a little thin depending on what you are lifting. The uprights are woefully inadequate for members in compression to lift any kind of load, and you have further comprimised their colum strength in one axis by welding the side braces at the mid point(their weakest point in compression). The small angle braces at the top are not large enough/do not form a large enough triangle with those tiny legs.

What is going to happen, is that you are going to try and roll that thing lengthwise on those little casters or slide a weight along the beam, and something is going to hang up. the stored momentum from the moving load will put a side load on the legs in their weakest axis and either they will both collapse, tripping the whole affair thru a wall, or one side will collapse first, kind of like an elephant kneeling, which will probably collapse the other side in the same fashion and probably drive that crossbar back in to whoevers pushing it's ankles.

The colums need to have a much larger cross section to resist bending. I would say at least as large as the base crossbars where the casters are attached, and be fairly heavy gauge. Multiple load paths are also your friend. If I was to build one, I would probably skip the single center colum all together and go with two angled side "A" frames, perhaps something like the attached drawing. I would move the upper angle braces from inside the trolly to outside and make them longer and of box or round tube. Angle iron is really poor for a compression member.

It sounds as if you make money working on lawnmowers? What is your continued health and ability to work worth? If it were me, it would certainly be worth a few more dollars in steel to make a tool I could trust my life to, as you will be doing working under that thing.

Good luck
 

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   / A Frame or Gantry Lift #5  
Now what are you going to use for engine hoist outrigger legs ?
 
   / A Frame or Gantry Lift #6  
bal0123,
I've attached a few pics of mine. Mine was bought about 30 plus years ago and has a 1 ton capacity rating. I know for a fact that rating is underestimated. Perhaps you can get some ideas to strengthen yours since we certainly don't want to see (or hear) of anyone getting hurt.
 

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   / A Frame or Gantry Lift #7  
bal0123,
I've attached a few pics of mine. Mine was bought about 30 plus years ago and has a 1 ton capacity rating. I know for a fact that rating is underestimated. Perhaps you can get some ideas to strengthen yours since we certainly don't want to see (or hear) of anyone getting hurt.

Most if not all commercially built lifting devices have a 3:1 lifting ratio. This means if it's labeled for 1000 lbs the thing can actually lift 3000 lbs before the component stress's are actually near the yield stress of the material being used.

Honestly I wouldn't lift my lawnmower with that home made unit, and I agree it will buckle and fold over very quickly. One thing I have seen in the mill, when failure comes it comes quickly and without warning! Better to be safe, then sorry.

Craig
 
   / A Frame or Gantry Lift #8  
I guess these aren't the hoped for reactions, but if they prevent a hugely expensive trip to the ER, then we can all be grateful.

I wonder if there is a way to modify the cherry picker base to get it to do what you need?
 
   / A Frame or Gantry Lift #9  
bal0123,
I think if you added some full length braces from the top to the rolling base instead of just the short bracing you have at the top it would be much stronger. Start just past where you welded your brace (about 2' in from the end) and go down to each of the 4 corners.
 
   / A Frame or Gantry Lift #10  
a frame with some more solid members then the uprights currently. the 1 ton is an excelent modle. since i cant see those casters well my 2nd thing would be to make darn sure they are rated for a good ammount of weight and are in excelent working order. those would be the easiest folding point on that unit. the worst part about one of those folding is it would flop the whole thing on its side with momentem or twist it like a pretzle.
 
 
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