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Adalius

Mechanical
Feb 13, 2009
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I'm scratching my head (since I'm just a dumb construction worker ;) and figured maybe someone here could come up with a brilliant idea that I'm overlooking.

Background:
We have a large skidding system; essentially it's two heavy steel beams fully reinforced with two inverted channels (picture a cap channel not welded to the beam) on which the item we need to move (typically heavy transformers but whatever our customer wants) sits. Two large hydraulic cylinders pinned to the beam push the channels along the top of the beam, the pins are then removed, cylinders retracted, pins reinserted further along the beam, and then the cylinders re-extended in this fashion over and over to crawl the load forward. It's a fairly common piece of equipment in our line of work. The channels put about 100-140psi onto the beam at full load, but a more common operating range is about 50-70psi given that most of the cargo isn't at the systems maximum weight.

Traditionally we used to use a paste made of ivory soap flakes to lubricate it during use (economically, it was cheap, environmentally, it washed away and the volume we used wasn't a concern at a given site). The problem with flakes was two fold, primarily Ivory stopped selling them in 1993 and other brands just didn't work as well, and secondly, the paste is hard to work with when it's below freezing, which is quite common for our work here in Wisconsin. We were using grease afterwards but as you can imagine, that makes a huge mess since the surfaces are exposed (80' or so, 12" wide, right in the middle of construction sites) so they not only collect all sorts of dust and dirt but also get all over the workers.

We worked with a plastic engineer to design some low friction lubricant impregnated polymer plates to install on the skidding surface to use instead of the soap flakes and grease. In testing they work just fine. The problem we have right now in the short term is the beams have been cleaned and prepped for the plastic install (fastener holes drilled/tapped/etc, repainted), but some emergency jobs came up that we need to use the system on before I can get the rest of the project finished to the point where we can utilize the new plastic wear plates. So in the interim I need some lubrication options better than what we have.

So to summarize all the above:
Is there a good lubricating option for this situation that anyone can think of that is:
A) Economical (~$10-20/gallon)
B) Environmentally friendly/less messy than grease (water soluble but able to handle temps down to 0F would be ideal)
C) Comparable friction reduction to grease/soap.
D) I would imagine it needs to be thick like a grease/paste for our application too.
E) Removable without too much effort when we get ready to install the plastic finally (steam cleaner removable, etc)

Hopefully one of the wise sages on this site has some ideas. :)
 
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Seems like in your business you would have tried electrician's cable pulling soap, good to -20F -


Also, a word of caution on your polymer skids - steel beams can expand/contract at about 1:10 ratio to the plastics. Make sure your plastic skids are designed for differential thermal movement of the steel, or you'll end up breaking the holes out on the skids.
 
There's a good 1/4" of play between the steel and polymer on the edging, and the bolt restraints were engineered by the plastic company with tapered head bolts installed in a manner that gives them some slop to allow growth parallel to the fasteners axis so that shouldn't be an issue.
 
Adalius,
You could look at Xanthan gum,
Xanthan Gum is specially produced as mud additive for oil drilling and exploitation.
It is also used as thickener/ food additive.
It is available as a brown powder which when mixed with a surprisingly small amount of water, produces a compound that is slipperier than snail snot.
It is very similar in feel to the cable pulling compounds mentioned earlier. When exposed to the weather it is subject to bacterial attack, so hose it off quickly after use.
B.E.



You are judged not by what you know, but by what you can do.
 
Can you spray vegetable oil ( PAM ) on the surfaces?
Would a laundry detergent work?
You could go to a nearby McDonalds and ask to mine their throw away deep-fry oil that is often turned into BioDiesel
 
One thing that also might help reduce friction between the rails and channels is using the hydraulic cylinders to pull the load rather than push the load. With the type of sliding contact present between the rails and channels, a "recess" sliding condition produced by pulling the load will create far less friction than an "approach" sliding condition produced by pushing the load.
 
Just saw my last post w/ typo. Meant to say "Amish enclave". Plenty of them in Wisconsin. Most are quite happy to do business with "Englisch".
 
tbuelna: Pulling isn't an option 95% of the time because of the way it's configured. We can't pull over the layover plates since they don't have the beam underneath them so there's nothing to react against, and the shoes are expandable with bolt on sections so they don't have eyes at both ends, if we want to switch from pull/push in the middle of a move you have to jack the entire load up, spin the shoes, relocate the cylinders and locking shoe, and set the load back down. When you're dealing with 200-500 ton that's a bigger task than it sounds like.
 
Adalius:
KY Gel works great for some applications, usually she’s warmer than 10̊F though. And now, Trojan and others actually have products which will make the main rail beams or the skid channels smile and coo, so they say, depending on which member they are applied to. :) I would make the ‘Duckbutter’ or the cable pulling soap work in cold weather by playing rose bud heating torches on the webs and undersides of the flanges of the main rail beams to warm them a little above 10̊F. I’ll bet that the lubricity doesn’t really disappear completely at 10̊F, the product just becomes much less fluid, and you might still have the cylinder pushing cap’y to slid the channels. Immediately behind the pushing cylinders I would use a long handled ice scraper to remove most of the lub from top flange of the main rail beams. I think I do understand the benefit of pushing cylinders as apposed to pulling cylinders; full fore of the cylinder pushing and pushing the load onto the trailer.

I’m in St. Paul, MN, so I do understand your cold weather problems. Are you in the Milw. area? The plastic bearing pads depend on running on smooth, clean rail surfaces and can be seriously abraded at any top flange roughness or joints in the rail beams. So, as a min. align the top flanges of the rail beams well, and grind a radius on the sharp edges which might contact the plastic pads. I’ve always run plastic bearings on plated, polished surfaces, not rough steel. Although, they can be replaced for a reasonable price as they abrade. It seems to me that the best design might be four plastic bearings (shoes) 18-24" long fixed to a 1" steel bearing plate assembly. Then, these bearing assemblies get located on the skidding channels as a function of the load application points on the loads which you are trying to move. And, the underside of the web of the skid channel is actually 1.75" above the top of the main rail flange.
 
The beams have cheek plates so heating the bottom of the flange isn't practical plus when you're dealing with hundreds of feet of beam that's a lot of labor which is why I'm keen on switching to something free flowing at below zero.

We are in the Milwaukee area. Oldest machinery moving firm in the state to the best of our knowledge. :)

As for the bearing pads, they specifically chose a polymer that is really durable on non-machined runners. It's actually primarily used as the bearing plates in mining shovels where they routinely turn into 'dirt mills' from all the stuff getting between them and the steel of the upper cab. The plastic is lining the beams not the shoes so we had them chamfer the leading edge on every skid plate and we're putting a leading chamfer on the steel shoe so they should ride nice with no sharp edges to cause any planing. We made them in 4' sections so that if one gets damaged/cracks/whatever we can replace it without having to redo the entire beam. All the bolts are flat head countersunk so they are well below the top of the skidplate to allow plenty of wear.
 
Adalius-

If you can't use the hydraulic cylinders to pull the load instead of pushing it, you might be able to produce a similar effect by adjusting the relative vertical locations of the hydraulic cylinder attachments. The difference in sliding friction produced at the rail/channel contacts can be quite substantial with recess vs approach contact conditions.

If the force vector of the pushing hydraulic cylinder is offset well above the forward contact point of the rail, then the pushing force will promote an approach type contact at the leading edge of the skid and greater friction. If the force vector of the pushing hydraulic cylinder was tilted so that it was offset below the forward contact point of the rail, then the cylinder pushing force would produce a moment that promotes more of a recess type contact at the leading edge of the skid and lesser friction.

Sorry if these suggestions are not practical for your current situation. But they are definitely something to consider with future moves.

Regards,
Terry
 
Adalius,
Molybdenum disulfide is a fantastic - one of the best - dry lubricants. Soybean and sunflower oils melt within a degree of each other at around 0 deg F. Blend powdered MoS2 with one of the above oils, and that should be slicker than pig snot. Biodegradable and pretty cheap, too. Pick your blending oil depending on expected temperatures.

References:

Alternatively, you could try talc blended with an oil that's semi-solid at the expected temps. It's almost as good a lubricant as MoS2, and much cheaper (think baby powder).

I grew up in Cedarburg (just north of Milwaukee, for those not from WI) so I know the cold you speak of :) It feels like your face will fall off some winter days.


SceneryDriver
 
TBuelna, I'm trying to understand what you're saying and coming up empty. ;) Currently the cylinders are set to the eyes are approximately the same height, meaning the cylinders are parallel to the direction of travel (more or less). Are you saying that it should be tilted so it's higher at the load side or higher at the dead-end side?
 
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