Beefing up a shop crane

[Sincerd]

Okay so I got the shop crane thats 2 ton. I need to lift more than 2 ton. Closer to 5k but only 2 in off the ground and it's got a flat bottom so it's not going to tip or anything. If this was something like an engine or a odd shape item that may roll, I wouldn't do it.

What is the weak points to the shop cranes? I've seen them Buckle right over top of the ram, but where else? Seems like very little material holding the feet pins in place. I'll update with pic.

I welded plates onto the end of the tube so far. Changed most of the bolts (will change all) to grade 8.

Some of the welds I could see porosity, so I will grind a notch in them and run a better bead.

Cut off 2 section of 4 links of g70 chain and fixed to 4 ton swivel hook

Thinking of running quarter inch plate down the length of the Boom basically sandwiching the non-adjustable boom section. Will have to drill holes for the adjustment arm.

 

[Sumboodie]

Weifgt limit is it tipping forward or the jack hitting relief pressure

If it bends before that, it was a seriously **** design!

 

[ItsNemo]

Can you lift one side, block it up, and then lift the other side? Or does it need to actually float in the air? 2 inches is next to no height.

 

[Sincerd]

Can you lift one side, block it up, and then lift the other side? Or does it need to actually float in the air? 2 inches is next to no height.

I build a mobile base out of angle iron. I'm going to try to do one side and then the other but I think at some point it needs to go at least two to three inches in the air

 

[GeoBruin]

I'll probably catch heat for this but for a 2 inch lift, I think I would be willing to test the safety factor on the crane. If it simply won't lift whatever you're lifting off the ground, you'll likely have your answer and there's no harm done (except maybe to the crane). As a bonus, you'll probably know your failure mode.

If it does lift it off the ground, the odds of it failing in the few moments it takes you to place your base underneath (and under static conditions) seems very small.

There... I'm already regretting saying it...

 

[alwaysFlOoReD]

So you're lifting 1/2 ton over rated 2 ton capacity? Im pretty sure there is a 3-1 safety built into the rating. I'd have no problem lifting your piece...

 

[dogdog]

Shop cranes are weird. If it is a 2 ton. The 2 ton rating is when it is not extending the arm. The more you extend it the less rating goes down

 

[Sincerd]

Can you lift one side, block it up, and then lift the other side? Or does it need to actually float in the air? 2 inches is next to no height.

I build a mobile base out of angle iron. I'm going to try to do one side and then the other but I think at some point it needs to go at least two to three inches in the air

 

[AEAdam]

The piston could fail. The brackets that attach top and bottom to the hydraulic cylinder. They should be as close to the cylinder holes as possible and thick. Then their attachment should be really good, specially at the bottom. Section of the main post and the crane arm kinda are what they are, but both see bending and could buckle

 

[Sincerd]

 

[Sincerd]

Column to base was staring to bend. My guess is someone torqued down on the bolts. I wanted a plate there.

 

[LopezBart]

You can quickly figure out the load on the ram by measuring the travel of the ram and the travel of the lifting hook for a small movement in the desired lifting position.

load on ram = weight * travel of lifting hook/travel of ram.

So if the 5000 lb load would move 2 inches while the ram moves 1/2 inch, the load on the ram is 20000 lbs.

- Bart

 

[ipgenie]

Seems like there are a few failure videos showing failure at the boom where the ram connects and then when that's reinforced, next was one of the legs.
I don't remember for sure but it seems like I saw a couple of these on YouTube. Probably more than a 5k static lift though.

 

[Sincerd]

Seems like there are a few failure videos showing failure at the boom where the ram connects and then when that's reinforced, next was one of the legs.
I don't remember for sure but it seems like I saw a couple of these on YouTube. Probably more than a 5k static lift though.

Can you share video?

 

[LopezBart]

Here's a buckled one:

 

[Sincerd]

Heres where I'm at so far. Widened the base with 5/16 vs the existing 1/8th inch. Probably going to weld a plate inside the tube legs. I'll upload pic, hard to explain.

 

[speed bump]

I would probably stitch weld some ******** the sides of the beam and reinforce the column so it can't bend easily. Maybe a piece of plate across the front side of the tube that carries the column on the base. Otherwise some reinforcement at the pivot point (probably just weld on washers) and the lift point.

Judging by my escapades with mine the ram will be your limiting factor. As far as what you are lifting just do a side at a time.

 

[Sincerd]

I would probably stitch weld some ******** the sides of the beam and reinforce the column so it can't bend easily. Maybe a piece of plate across the front side of the tube that carries the column on the base. Otherwise some reinforcement at the pivot point (probably just weld on washers) and the lift point.

Judging by my escapades with mine the ram will be your limiting factor. As far as what you are lifting just do a side at a time.

Can you draw what you're trying to describe? I did well washers to the Pivot Point

 

[finn]

By the time you’re done adding all that steel, are you sure you’re strong enough to push that thing around?

 

[Sincerd]

By the time you’re done adding all that steel, are you sure you’re strong enough to push that thing around?

It's a lot. But it's also super solid and with the new casters rolls easy

 

[Steve_P]

So, you are obviously doing a lot of work here. And maybe you've done this, but I don't see pics. You need to beef up the sides of the main lifting beam. Scab on some lengths of 3/16" thick X 2" (whatever) flat bar on both sides at critical areas. This will be your best bang for the buck and increase the moment of inertia against vertical loading. This is the issue with the "buckled" one in the pic above.

 

[Steve_P]

You can quickly figure out the load on the ram by measuring the travel of the ram and the travel of the lifting hook for a small movement in the desired lifting position.

load on ram = weight * travel of lifting hook/travel of ram.

So if the 5000 lb load would move 2 inches while the ram moves 1/2 inch, the load on the ram is 20000 lbs.

- Bart

An easier way to do this is to just sum moments about a fixed point. Like the hinge point behind the ram. This will also be much more accurate because the distances are many times greater. All you need is a tape measure, a calculator, and the amount of weight that you want to lift.

I am not going to try to explain it, but it's very simple math; second year engineering statics and basic algebra; you can look it up online. Just look up "summation of moments" on google or a mechanical engineering forum.

Once you know this, you can also easily figure out the bending stresses in the lifting beam at various locations and this will help you with a failure load. This is also simple math since the original beam is a square tube. Look up bending stress, moment of inertia (i) square tubing, calculation of moment (M).... The formula is the bending stress = MC/i

 

[Sincerd]

So I think I have one more thing I want to do. I'm going to sandwich Steel on either side of the arm and drill holes for the PIN. Probably going to replace that pin with a grade 8 bolt. Probably way overboard but so far, it's much sturdier.

I reinforced the top and bottom of the ram connections. I reinforced all the bolt connections with square tube or plate welded inside the tube as seen in the picture. I bored out the main screw connection to a 1x8 grade 8 bolt and replace pretty much everything else with Grade 8 fasteners.

 

[Jim greengo]

Can you get a skidloader in there?

 

[Sincerd]

Can you get a skidloader in there?

Not looking like it but I'm going to throw the lathe on six or eight 1500lb albion casters and winch it up a drop deck trailer

 

[LopezBart]

An easier way to do this is to just sum moments about a fixed point. Like the hinge point behind the ram. This will also be much more accurate because the distances are many times greater. All you need is a tape measure, a calculator, and the amount of weight that you want to lift.

I am not going to try to explain it, but it's very simple math; second year engineering statics and basic algebra; you can look it up online. Just look up "summation of moments" on google or a mechanical engineering forum.

Once you know this, you can also easily figure out the bending stresses in the lifting beam at various locations and this will help you with a failure load. This is also simple math since the original beam is a square tube. Look up bending stress, moment of inertia (i) square tubing, calculation of moment (M).... The formula is the bending stress = MC/i

Perhaps in this case that's easier... but when linkages get complex, the energy method (displacement x force = displacement x force) save a lot of work, since you only care about the input and output. Both are useful techniques.