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crane uprate - where would you add some metal ?

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Nicholas Farr09/02/2021 08:36:44
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3136 forum posts
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Hi Gerry, in answer to your question and simply put, the only place I would add any metal would be what I would lift on the hook and this would only be up to it's maximum rated load.

As has been said, if you need to lift anything heavier, get or hire a larger rated one. Altering lifting equipment will invalidate any warranty and would make it unsafe for anyone to use. Liabilities could be a problem if you ever sold it on after modifications. Lifting operations and equipment are one of the biggest causes of injury in the work place. So if you what to alter it, you should do it off your own bat.

Regards Nick.

Stueeee09/02/2021 09:37:16
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107 forum posts

The only modifications I would make are change out the fixed casters which make steering a loaded crane very difficult in my experience. Possibly something to grab hold of so that you can move the loaded crane would be useful too. This is my 2 tonne folding engine crane -I use it a lot, but have yet to lift an engine out with it.

I fitted the swivel casters and the "handlebar" at the rear. I also changed the chain and hook to one that came with certification paperwork.

Oven Man09/02/2021 09:44:06
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This must be the first time there has been unanimous agreement on how (or not) to proceed.

As everybody else says, just don't do it.

Peter

mechman4809/02/2021 10:51:09
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2938 forum posts
466 photos

Simples; don't do it I bought the 1 ton version with foldable legs & jib that folds down to install my WM250V-F lathe & WM16 mill into my garage conversion, no probs, & it now stands all folded up in the corner of my garage neatley tucked away.

George.

Nigel Graham 209/02/2021 10:58:28
1897 forum posts
26 photos

Besides, the hire-cost for the very occasional heavy-list may well be lower than the materials and electricity involved in modifying an existing hoist - certainly lower than repairing a broken machine-tool.

'

I'd add only that if you need carry out lifting operations that any shackles, eye-bolts/nut and slings are the proper ones for the task, and are used correctly. No slings frayed, knotted, over sharp edges or forming legs at > about 90º; no dynamo eye-bolts for angular loads; no shackles that are distorted or have pins not their own or replaced by bolts....

It's not worth make-shifting lifting-gear unless you can be really sure of what you are doing and test each stage as you go; and to be honest, using proper lifting-equipment is very often easier than make-shifts.

Nor are they particularly expensive - certainly not as expensive as a dropped lathe. Or as one lifted by a sling of correct type but apparently knotted (never knot lifting slings) and round its spindle - reassure us Stuee, that you didn't really do as your picture unfortunately implies!

If you need make up rope slings or rope block-and-tackle, be sure of your materials and of your knots and splices.(An eye-splice is inherently stronger than a knotted bight, and more compact, but harder to make correctly.)

'

I have built a travelling-hoist for my workshop, but from chain-block to load is all proprietory lifting-gear, and I am very well aware that I could not design the hoist and rails mathematically, nor give it any more than a very rough load-test. Its heaviest loads to date were an Elliot 'Progress 2G' bench-drill with the table removed, and the body only of a Denbigh H4 horizontal-mill; but I watched everything very carefully for any signs of distress while raising the load the first inch or so above the floor, and when traversing the assembly. It intended uses are manipulating quite modest loads as a helping-hand rather than brute machine-tool moving.

Mike Poole09/02/2021 11:17:32
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3157 forum posts
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I would recommend just getting a bigger hoist if larger loads are a real possibility. Increasing load capacity tends to grow the whole device and use thicker material and larger pivots and fasteners. As with tuning a car everything needs to be updated, brakes, suspension, the body, the clutch, the wheels, the driveshafts and so on. I notice that no one has volunteered the redesign required to uprate the hoist, probably because it would be quite a lot of work and liability for any suggestions could lay with them. Remember that this is a widely used forum and you may not be the only one doing any suggested modifications. For everybody’s peace of mind it would be best to go with the overwhelming opinion to use it as supplied and within its stated limits. I hope you don’t feel everyone is just being negative but are concerned that you continue to enjoy your home workshop. I once saw a half ton chain block used to lift a 2 ton robot, no one got hurt but the chain block was only fit for the bin.

Mike

br09/02/2021 11:27:13
833 forum posts
7 photos
Posted by gerry madden on 08/02/2021 18:59:26:

I bought this small engine crane for lifting things in the workshop and garage a while back. Its rated at 200Kg and 500Kg at maximum and minimum extensions of the jib.

So far this capacity has suited my purposes very well. However one day i may need to lift something heavier so before that time comes I might undertake a little project to add a little more robustness.

I haven't done any calculations on it yet but before I do I thought I'd ask the structural stress experts here where from experience (bitter or otherwise) they might be inclined to beef it up a bit ?

My first thoughts are the rear wheels !

dscn8061.jpg

As a recently fully qualified structural stress engineer - simple - NOWHERE wink

br

Nigel McBurney 109/02/2021 11:40:24
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962 forum posts
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I have a 1 tonne engine crane,the fold up type,it is useful but cannot reach a lot of jobs due to the width of legs when folded out,its not very good loading full size stationary engines onto their trolleys,though it can lift loads into estate cars ,vans and trailers and will not reach over a large lathe such as a Colchester as the legs hit the brake safety bar,though the legs will go around most milling machines,to get heavy loads onto the table or removing the vertical head off a turret mill. I have aquired a hook with swivel so that loads can be rotated (carefully) I watched a web video where someone had to load a large billet of steel on a lathe of around 8 inch centre height,the right hand moveable leg was left in its "park" upright position the othe leg fitted around the LH side of the headstock and the billet was loaded easily to the chuck, looked silly and dangerous but the crane was only lifting around a tenth of its max load and on the video the crane did not tilt to one side as I expected. I had a thought ,why not extend both legs as per normal and use a longer extendable jib,thats the bit of the jib thats usually painted black, so that I could lift a heavy chuck or faceplate onto the lathe spindle ,and the did not foul the lathe, so I tried it a 15 inch longer extension allowed me to lift a a 21 inch face plate onto a triumph lathe,the rear end of the crane did not look like lifting and was stable. Ok if care is taken and relatively light loads ,its just that I am too old to lift a big faceplate. For most of my lifting I use 10 and 30 cwt Felco chain hoists ,they are industrial types and can be overloaded by 50% only snag is that a decent beam is required, A pallet truck is useful at times,though requires a flat smooth surface when shifting with heavy loads . The hoist to avoid is the lever type Pulift, safe for pulling along the loads horizontally,but can let when lifting /lowering vertically,

gary09/02/2021 11:42:49
135 forum posts
31 photos

nigel graham, could you please explain why it is not ok to lift a lathe of that size by its spindle

larry phelan 109/02/2021 11:43:22
1139 forum posts
14 photos

As so many others have said DONT EVEN THINK ABOUT IT !!

If ever there was a case of letting sleeping dogs lie, this is it !

A trip to Rehab is worth while if only to see the results of silly undertakings.

Some of the things people do ???????????!sad

JasonB09/02/2021 11:50:36
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Nigel G looking closely at the photo the sling appears to be wrapped several times around the base of the headstock and then passes up through the bed with one end of sling passing either side of the spindle, not lifting by the spindle.

Howard Lewis09/02/2021 12:55:29
5744 forum posts
13 photos

To join the chorus saying DON'T do it!

Because

1 ) It may no longer be safe. Cracks could appear at the edge of any welds that you make.

Any increase in one part of the structure will mean that the stresses in other parts will increase, possibly to the point of failure.. So everything would need to be strengthened.

If it fails and someone is injured, who ever made the modifications would be liable.

2 ) Not really practicable. Adding depth to the inner part of the job, might be possible BUT not to the outer,part since that it would prevent any adjustment of the position.

You have no assurance that the ram would be capable of lifting the increased load.

So, again DON'T!

The easiest, and safest way to lift heavier loads is to buy a higher capacity crane.

Howard

SillyOldDuffer09/02/2021 13:58:57
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7898 forum posts
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Posted by Nigel Graham 2 on 09/02/2021 10:58:28:

... Or as one lifted by a sling of correct type but apparently knotted (never knot lifting slings) and round its spindle - reassure us Stuee, that you didn't really do as your picture unfortunately implies!

...

Looking closely at the picture Stueeee is innocent of that crime, but there is another potential 'avoid' in the photo:

It's lifting a lathe with a sling whilst it's bolted to the stand. Lifting both together puts a lot of unusual stress on the lathe's bed and feet. Cast-iron is weak in tension, which is what the stand does to the lathe during the lift. I doubt the bed would break, but it might bend or twist. Or the stand might be damaged.

Less risky to take the lathe off the stand first, move the stand on it's own, and then replace the lathe.

Dave

not done it yet09/02/2021 14:07:57
6509 forum posts
20 photos

OK, only two posts even possibly suggesting modifying it, neither of which should fly. A stronger cylinder might be tempting (for the operator to add) - with it so easy, then, to lift a too-heavy object - and the second (which seemed to be a more likely suggestion to modify) forgets that swivelling wheels can cause a tip-over if turning - these things are sold as hoists, not travelling cranes. At full load, I would only be using it as a hoist, if at all possible (lift the engine and and move the vehicle is safest). Movement is restricted to fore and aft for a very good reason!

Nigel McBurney 109/02/2021 15:02:17
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962 forum posts
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I had one of those plain bed Smart and brown lathes,the sub bed is heavy I admit ,welded 1/4 inch steel plate ,now a precision lathe of that type should NOT be removed from its sub bed,the top of the sub bed is machined level and the lathe is aligned and carefully fitted to it. You will find that a lathe bed of that precision is not soft cast iron as we know it ,but an alloy cast iron which is strong. and can e lifted carefully in one piece.I once scrapped a J &S surface grinder,the top table on these looks slim and fragile,try hitting it with a 14 lb sledge, the hammer just bounced off,amazingly strong.Thats what you get from good UK built machine tools.

Liam Cook09/02/2021 15:24:14
13 forum posts
3 photos

For what it's worth I'm an engineer, I design things for a living. I'm not mechanical but I have some thoughts.

1. Don't do it unless you really really know what you're doing and you have no other option.

2. For the cost... a bigger, more able crane can be had for not a lot less, please consider this

That crane, you have no idea why its rating is only 200kg, and you dont know the stress' going through each part of the frame, so you have no idea where it might fail which means you can't say you've beefed it up in the right areas. In short, you have no idea what the basis of safety is and it could fail unexpectedly. And this is before we starting thinking about fatigue, about peak load stress, about the fact its a mobile crane and dynamic stress.

I'd either buy a bigger one and be done with it, or build one from scratch, but in typical engineering fashion, it would be over designed to hell :D

Nigel Graham 209/02/2021 16:34:35
1897 forum posts
26 photos

Jason, Dave -

Thank you for putting my mind at rest! I had enlarged the screen 4 times but it still wasn't quite clear.

I must admit I'd missed the point about lifting the cabinet via the lathe though.

SillyOldDuffer09/02/2021 18:14:27
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7898 forum posts
1725 photos

Looking at the crane I think it's designed to fail close to the ground at the rear.

enginecrane.jpg

The side struts and front wheels are suspended from the rear cross-bar and wheels by two bolts, circled in black. This construction is much weaker than resting the struts on top of the cross-bar because this way round the bolts can pull through the holes.

I think the weakness is deliberate: if the crane is overloaded the bolts break through the top of the cross-bar and the whole rear of the crane drops an inch on to the ground, where it rests safely. At this point it's very obvious the crane has broken and most people would proceed with caution!

I guess the rest of the crane is designed to the same common safety factor. To take more weight the hook, chain, beam dimensions, pin joints, welds, axles and ram would all need to be upgraded. That is rebuilt as a bigger crane.

Anyone care to try breaking one to see if I'm right? (Please don't!)

Dave

Sam Longley 109/02/2021 19:03:16
917 forum posts
34 photos

If it were to fail I would expect the rear castors first. That would put side strain onto the jib & cause rapid twisting & rotation causing miss alignment of the ram. the jib section would no longer be square to the load & twist further allowing further rotation & then bending failure & tipping as the load swung outside the limit of the feet

So i would look at better wheels then a couple of side stays to support sideways movement & twisting of the vertical jib section.

Possibly bolt a cross stay to the feet to increase width to prevent undue tilting sideways & fit the supporting stays to that

However, if one has only a single job & one does not even know what it is going to be, then the exercise seems pointless. Hire a more suitable tool

Edited By Sam Longley 1 on 09/02/2021 19:05:08

Howard Lewis09/02/2021 19:10:33
5744 forum posts
13 photos

When the crane is loaded, the short cross bar between the legs will be subject to torsion, while the bolts retaining it to the legs, and those at the top and bottom of the the tie (Between the rear cross bar and the back of the semi vertical beam ) and the pivot for the jib will all be in shear.

The only beam that will be most weakened by the drillings for the bolts will be the cross beam at the rear. This is the only part where a hole is through the vertical face, which is the more important part of the box section beams.

The flat upper and lower faces of the beams contribute far less to the vertical strength than the vertical faces

The upper and lower faces prevent flexing in the horizontal plane, and so should be less highly loaded in a device intended for lifting..

BD^3 / 12 and all that.

The main thing is that the OP takes notice of all the advice saying "DON'T"

Howard

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