22 replies to this topic

[MatsNorway]

Hi

 

Does anyone know where i might buy guides for cylinders doing some lifting? i am lifting about 1800kg. With a Enerpac sylinder RC-50-25

 

I was thinking they might need some support. On monday i am going to do a round and hear with people but i thought you guys might had something and would even end up discussing it a bit. And thats allways a good read.

 

No one ever spesifies the actuall loads a cylinder could take but there has to be some right?

 

I use Norelem alot but none of these seems to be for this.

http://www.norelem.c...ide-system.html

 

Edited by MatsNorway, 25 April 2014 - 14:04.

[MatsNorway]

Basically this. Asked Rexroth on mail on they had something like this

http://img.directind...690-3587637.jpg

[Greg Locock]

You are trying to prevent side load on the top seal and buckling of the rod and perhaps bending in the min tube? 

[Wuzak]

Enerpac's catalog states:

 

 

Manufacturer’s rating of load and stroke are maximum safe limits. 

Good practice encourages using only 80% of these ratings.

http://www.enerpac.c.../rc_326e_gb.pdf

 

For a cylinder of rated capacity the size of the rod, seals, etc, should be sufficient to prevent buckling at that load, or any other issues with the cylinder.

 

I take it that the load you are lifting is somewhat larger than the cylinder and you are trying to provide a stable lifting platform?

 

RC-50-25 - would that be a 25mm stroke?

[MatsNorway]

Not buckling, too short for that but otherwise correct Greg

 

RC-51-25 i guess would be more correct. 25mm travel yes. 5tonn capasity each. Plenty margin.

 

I can hear with them on that Wuzak but surely they have some limits on those things.

 

In general i seek knowledge of the different manufacturers and their products.

 

ex: OT: KIPP got balljoints i found out. http://www.kipp.com/....ag/Joints.html

Thats my go to supplier for that if i need it now.

Edited by MatsNorway, 26 April 2014 - 08:18.

[bigleagueslider]

Hydraulic cylinders are ony designed to handle direct compression/tension forces. If the cylinder is subject to any side loads or moments, it will require some other device to handle those loads. Side loads or moments applied to the cylinder end attachments will result in leakage and/or excessive wear in the cylinder seals and bushings. If your application requires a pure linear motion, then some type of parallel shaft and bushing mechanism should work. If your application can accept a slight angular motion over the vertical travel, then you might consider some form of hinged lever mechanism.

[MatsNorway]

That was my assumption. I look for the parallel shaft and bushing mechanism.

[MatsNorway]

Surprisingly Rexroth had nothing for hydraulics. He only found something for Pneumatics. Going to see if i can use those. Should be strong enough.

[Kelpiecross]

The place where I get my machining done routinely makes up "bespoke" (if that is the word) hydraulic cylinders and pistons for special purposes. Hard chrome plated rod is available for pistons off the shelf (up to six inches in diameter) and the cylinder is fairly basic machining - it's a hole in a lump of steel. May be you could consider designing/making your own system?
.

[MatsNorway]

Done it before but not liking it. It worked fine and perfect after some minor honing but surely someone should have something out of the box. If im making it again im going to go finer on the tolerances. See how smooth i can get it. Its kinda tricky with the tolerances but i know how now.

Edited by MatsNorway, 29 April 2014 - 14:54.

[bigleagueslider]

Can you describe the size and shape of the load you want to lift?

[MatsNorway]

2m long 0.5 wide 1800kg. 0.5m-1m high Sylinders aligned with the length.

[bigleagueslider]

Is the load CofG located over the cylinder axis? And how stable is the load that is being lifted? Even if there are a pair of linear bearings/shafts constraining the vertical motion of the hydraulic lift, an unstable load can create large moment frictions in the linear bearing/shaft contacts.

[Greg Locock]

You might find it is cheaper to specify a very big ram and not bother with guides. That is often done on transmission hoists.

[Kelpiecross]

I presume you can't lift the engine with a crane and chains etc? I always find that lifting engines or gearboxes etc. from underneath with a jack to be fairly dodgey - lifting from above is always better.

[MatsNorway]

Bigleagueslider if stable as in solid.. extremely stable. CoG is not known but i just figured out a way to find it. But i think im just oversizing the guides and be done with it.

 

Greg: What you mean by ram?

 

Correct Kelpiecross. Must lift from underside.

[Greg Locock]

ram=hydraulic cylinder

[bigleagueslider]

Bigleagueslider if stable as in solid.. extremely stable. CoG is not known but i just figured out a way to find it. But i think im just oversizing the guides and be done with it.

The reason I ask is in the OP you noted that the load being lifted is 1800kg, which is quite substantial. And in a later post you posted a link to a single pair linear bearing/shaft system that looked to have a relatively small footprint. Thus it would likely have limited capability to handle moment forces in at least one direction.

[MatsNorway]

The side loads should be quite small. Guys will use the hydraulics to lift the bugger of the frame and then push on it, rolling it back/forward on rails. in have made rails in both directions to ensure you get it back into position easily.

[SimonW]

Most industrial installations I have seen for this type of lifting use scissor lifts, which I think are much more capable of handling off-centre loads.  Random examples:-

 

http://www.lkgoodwin...uty_lifts.shtml

 

http://solvinginc.co...lift_tables.htm

 

http://www.uni-craft...issor_lifts.php

 

Simon

[Kelpiecross]

Most industrial installations I have seen for this type of lifting use scissor lifts, which I think are much more capable of handling off-centre loads.  Random examples:-
 
http://www.lkgoodwin...uty_lifts.shtml
 
http://solvinginc.co...lift_tables.htm
 
http://www.uni-craft...issor_lifts.php
 
Simon

This would seem to be the most sensible way to lift the engine.

[MatsNorway]

Thats just overkill in terms of costs, both in initial and in maintenance as wells as complexity. A solution like that is also probably too high. A table like that is probably around 3k-6k$

 

Edit: if its a manual pump it could be cost efficient. Going to look for that.

Edited by MatsNorway, 05 May 2014 - 12:03.

[MatsNorway]

The crane was given a "retune" by the manufacturer. Cost a little bit as manufacturer wanted to do it themselves. In addition we will try to make some new bolt holes to make the lifting of it according to the rules.