Timken OK Load Tester

What is the Timken OK Load Tester?

A Timken OK load tester presses a rotating steel cup against a stationary steel block in lubricant and finds the highest load passed without scoring. It screens the load-carrying capacity of heavy-duty greases and gear oils under ASTM D2509 and D2782.

Overview

A hardened steel test cup (ring) rotates at 800 rpm against a stationary block with line contact, supplied with lubricant. Load is applied through a lever arm with weights, typically ranging from about 25 N up to several hundred newtons or about 60 lb in steps. After a 10 minute run, the block scar is inspected for scoring or galling. The OK value is the highest load at which no scoring is found, and the score load is the next higher load where scoring occurs. The line contact produces a high contact pressure that mimics gear and bearing sliding. The test is simple and low in cost but only ranks severity qualitatively, so most laboratories use it for heavy-duty industrial greases and open gear lubricants.

How does it work?

Wear analysis in lubricant laboratories follows two approaches. Tribometers place two surfaces in contact under a defined load, speed, temperature and lubricant film, then quantify friction force and the wear produced, usually as a scar diameter, track depth or mass loss. Contact geometry varies: point contact in four-ball and ball-on-disc tests, line contact in block-on-ring and Timken tests, and reciprocating sliding in high-frequency rigs. Debris analysis instead examines particles already suspended in used oil. Ferrography deposits ferrous particles magnetically on a slide for microscope classification, while quantitative sensors measure particle mass and size ranges. Load cells, torque sensors, temperature control and displacement transducers provide repeatable data, which is interpreted against standard limits or against a reference oil.

What are the key features?

• Line-contact ring-on-block test geometry
• Fixed 800 rpm spindle speed
• Lever arm loading with calibrated weights
• Lubricant delivery by pump or grease packing
• Simple operation with low consumable cost

What are the technical specifications?

A typical timken ok load tester configuration offers spindle speed of 800 ± 5 rpm, test duration of 10 min, load range of ≈ 20–400 N (lever weights), test ring of Case-hardened steel cup, test block of Hardened steel block and lever ratio of ≈ 10:1. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Timken OK Load Tester is used in heavy-duty grease screening, open gear and industrial gear oil QC and steel mill and mining grease qualification. Across the wider Wear Analysis class, laboratories also deploy it for anti-wear additive evaluation, extreme-pressure oil and grease screening and friction coefficient research.

Which standards and certifications apply?

Relevant standards and methods include ASTM D4172, ASTM D2783, ASTM D2266, ASTM D5183, ASTM D2714, ASTM D2509 and ASTM D6079. Certification candidates for this model are CE and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Tribological tests are sensitive to specimen quality, so use certified steel balls, rings and blocks with specified hardness and surface finish, and clean them with the solvent sequence the method requires. Check load and speed calibration with a known reference oil periodically. Fit guarding around rotating parts and use ventilation when testing heated oil. Keep room temperature stable, because ambient conditions influence friction. Measure wear scars with a calibrated microscope and record at least two orthogonal diameters per specimen. For debris analysis, take oil samples under consistent conditions and from the same point. Maintain records of calibration and reference checks, and report results with the method's precision limits in mind.

How do I select the right Timken OK Load Tester?

Choose a Timken tester when your customers or specifications require an OK load value for greases and gear oils. Use a four-ball machine for general anti-wear and EP ranking. Specify weight set, test block and ring supply, lubricant delivery method and compliance with ASTM D2509 or D2782.

How does it compare with other Wear Analysis variants?

Select the instrument from the property and specification being tested. Four-ball machines are the standard for anti-wear and extreme-pressure ranking of oils and greases, and most product specifications cite them. Pin-on-disk and block-on-ring rigs suit research into friction coefficient and material pairs, and allow flexible speed and load. Reciprocating rigs reproduce diesel fuel and thin-film lubricity. Timken testers screen heavy-duty greases and gear oils. Wear debris analyzers serve maintenance programs rather than product qualification. Compare load range, speed range, temperature capability, specimen cost, data acquisition and the ability to follow the exact standard. Consider operator safety around rotating parts and heated lubricant, and confirm supply of test balls, rings and blocks. In the RFQ, list methods, maximum load, temperature and any humidity or atmosphere control.