Timken OK Load
Encyclopedia
Timken OK Load is a qualitative measure that indicates the possible performance of extreme pressure additives (EP Additives) in a lubricating grease or oil. The units of measure are pounds-force
or kilograms-force
and are determined using a special test machine.
The test machine is based on a machine manufactured by the Timken Company
from 1935 to 1972. It is now an industry standard test though the meaning of the qualitative measure has become less useful as the science of tribology
has advanced.
The test machine consists of a bearing race mounted on a tapered arbor
rotating at high speed. The race is brought into contact with a square steel test block under load. The contact area is flooded with the lubricant being tested. The Timken OK Load is the load at which the spinning bearing race produces a score mark on the test block.
Timken OK Loads are still listed on grease and oil property charts. 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-force (16 kilograms-force or 155 newtons) or more means that EP additives are present and working.
The Timken OK Load test specification is ASTM
D-2509.
Pound-force
The pound force is a unit of force in some systems of measurement including English engineering units and British gravitational units.- Definitions :...
or kilograms-force
Kilogram-force
A kilogram-force , or kilopond , is a gravitational metric unit of force. It is equal to the magnitude of the force exerted by one kilogram of mass in a gravitational field...
and are determined using a special test machine.
The test machine is based on a machine manufactured by the Timken Company
Timken Company
The Timken Company is a global manufacturer of bearings, alloy steels, and related components and assemblies.- History :The company was founded by Henry Timken in St. Louis, Missouri in 1899 and incorporated as The Timken Roller Bearing Axle Company. A year earlier, in 1898, Timken got a patent...
from 1935 to 1972. It is now an industry standard test though the meaning of the qualitative measure has become less useful as the science of tribology
Tribology
Tribology is the science and engineering of interacting surfaces in relative motion. It includes the study and application of the principles of friction, lubrication and wear...
has advanced.
The test machine consists of a bearing race mounted on a tapered arbor
Mandrel
A mandrel is one of the following:* an object used to shape machined work.* a tool component that grips or clamps materials to be machined.* a tool component that can be used to grip other moving tool components.- Variants :...
rotating at high speed. The race is brought into contact with a square steel test block under load. The contact area is flooded with the lubricant being tested. The Timken OK Load is the load at which the spinning bearing race produces a score mark on the test block.
Timken OK Loads are still listed on grease and oil property charts. 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-force (16 kilograms-force or 155 newtons) or more means that EP additives are present and working.
The Timken OK Load test specification is ASTM
ASTM International
ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services...
D-2509.