Plain Bearing Lubrication

[jmn]

I have a problem of stick-slip with slow moving flat plain bearings that only travel about 2 inches back and forth. A one time trial with EP grease solved the problem for a short time however there is no provision for regular greasing. The bearings are always loaded in the 3,000 to 5,000 psi range and it is very expensive and time consuming to take the bearings apart.

A hole can be drilled to the center of the bearing surface and high pressure lubrication applied up to 5,000 psi for grease and 15,000 psi for oil. Any ideas on whether this would would actually get lubricant to the bearing surfaces at these bearing pressures? What about with grease grooves?

 

[bobc]

pressure lubrication, along with grooving and/or flaking, will most likely cure the problem.
there is no mention of temperature, is this a factor?
there are also self lubricating materials available for applications such as this that can survive on minimal lube.
there are also many considerations such as water or dirt contamination to take into account.
can you share the application with us?

 

[jmn]

The plain bearing application is for the lateral rotation of the wheel truck system on a 150 tonne rail mounted crane. These slide bearings were originally bronze mesh reinforced PTFE. Each corner has a pair of bearings, each 100 X 470 mm. Movement is in the longitudinal direction. During a recent wheel refit, these bearings were replaced with a graphite loaded epoxy laminate running on a 316 SS surface with a 20 rms finish. This combination stick-slips when travelling in or out of the curved rail section. Accessing these bearings is a major project involving a complex jacking procedure and extensive downtime. Obviously we could go back to the PTFE material, however this involves jacking and possibly shop work. I am looking for the magic fix to avoid this if possible.

 

[JLW]

Have you looked at using a dry lubricant?
I found this site

http://www.slickote.com

 

[rhc]

PTFE significantly lowers starting friction. In some cases so does PE (polyethylene, the poor man's PTFE).
As I see it your options are
1) Grease or oil that is significantly loaded with either PTFE or PE and keep using it forever.
2) Fix a scrubber, made of either PTFE or PE (PTFE is better for lubrication but PE can handle higher compression before creeping) front and back of your bearing carrier. If you can apply an adjustable pressure to the scrubbers so that they always are pressing very firmly onto the sliding surface, the materials will transfer some of themselves onto the sliding surface and greatly reduce your starting friction. If your application is exposed to sunlight (UV rays) forget PE

 

[intertech]

have a look at

http://www.vesconite.com

Greetings,

Lex

info@intertechbv.nl