Timken OK Load is a standardised measurement that indicates the possible performance of
extreme pressure (EP) additives in a
lubricating grease or oil. The units of measurement are
pounds-force
The pound of force or pound-force (symbol: lbf, sometimes lbf,) is a unit of force used in some systems of measurement, including English Engineering units and the foot–pound–second system.
Pound-force should not be confused with pound ...
or
kilograms-force
The kilogram-force (kgf or kgF), or kilopond (kp, from ), is a non-standard gravitational metric unit of force. It is not accepted for use with the International System of Units (SI) and is deprecated for most uses. The kilogram-force is equal t ...
. This measurement is performed using a special test machine and standard block and ring test specimens.
The test machine is based on a machine manufactured by the
Timken Company
The Timken Company is a global manufacturer of bearings and power transmission products. Timken operates from 42 countries.
Company history
In 1898, Henry Timken obtained a patent for an improved tapered roller bearing, and in 1899 incorpo ...
from 1935 to 1972,
[ It is now an industry recognized standard test to compare extreme pressure resistance of greases and oils in a reproducible way.
It is not to be confused with some smaller lubricity testers that are also often erroneously called Timken: the confusion originates from a now obsolete Italian brand TIMPKEN.
The test machine consists of a standardized bearing race mounted on a tapered ]arbour
Arbor(s) or Arbour(s) may refer to:
Arts and entertainment
* Arbor (installation), ''Arbor'' (installation), a 2013 public artwork in Indianapolis, Indiana, US
* Arbor, a counterweight-carrying device found in theater fly system#Arbors, fly syste ...
rotating at high speed. The race is brought into contact with a square steel test block under a constant load. The contact area is flooded with the lubricant or grease being tested. The Timken OK Load is the highest standard load at which the spinning bearing race produces no scouring mark on the test block, but only a uniform wear scar.[
Timken OK Loads are listed on grease and oil property charts and are part of many specifications. It was once generally assumed that the measure and the film strength of the lubricant were directly related. Today, the primary purpose of the test is to determine whether EP additives are present and functioning. A measure of 35 pounds (16 kilograms-force or 155 newtons) or more means that EP additives are present and working well.][{{cite web , url=http://www.timken.com/en-us/products/lubrication/Pages/faq.aspx , title=Lubrication: Frequently Asked Questions , publisher=Timken , accessdate=2015-07-24 , url-status=dead , archiveurl=https://web.archive.org/web/20150725205013/http://www.timken.com/en-us/products/lubrication/Pages/faq.aspx , archive-date=2015-07-25]
The Timken OK Load test methods are ASTM
ASTM International, formerly known as American Society for Testing and Materials, is a standards organization that develops and publishes voluntary consensus technical international standards for a wide range of materials, products, systems and s ...
D-2509 for greases and ASTM D-2782 for oils.
There are a few portable versions of smaller testers utilizing similar test methods for public demonstration or for product showcase.
References
Mechanical engineering