2017 marks the 90 year anniversary of the Oilite bearing. It is widely accepted that Oilite bearings are still the undisputed leader in sintered self-lubricating bearings. But most people are not aware of how this titan within the industry came to be and the rich history behind it that has seen it used in everything from the the first Chrysler automobiles to the iconic British Supermarine Spitfire to modern day Formula One cars. In this blog, we will take a very brief look back at how Oilite bearings came into existence and just what makes them the very first and last word in quality and reliability when it comes to sintered bearings.
How to Solve a Problem Like Clutch Slippage…
The Oilite story forms part of the wider story of the birth of Chrysler Corporation and its engineering legacy. In 1924, Chrysler had launched its first automobile, The Chrysler 70 (aka the B-70). A six-cylinder car which was intended to provide the customer with a well-made, modern automobile at a more reasonable price than Ford and GM could offer. Chrysler went into a period of advanced engineering and testing, constantly looking for ways in which it could improve on its own designs. In 1927, Carl Breer, an automotive engineer, was hired as part of this campaign of advanced engineering and testing. He noted various problems with the vehicle’s clutch. One of which being that it would slip when oil or grease was packed in. The problem was thus; a cylindrical sleeve bushing of bronze was pressed into the flywheel end of the engine into which the extended end of the transmission shaft carrying the disc clutch rested. When the clutch was released, the bearing would revolve around the shaft holding everything in alignment. Excess lubricant from the engine was causing clutch slippage. The location of the clutch was inaccessible and therefore there was no easy way to force grease in form outside. It was only a matter of time before the bearing would become dry and begin to squeak when releasing the clutch. Oilless bearings seemed to be the answer. GM were manufacturing bushings of powdered copper and graphite compressed into a solid bushing at extremely high pressure. Breer tried these, but unfortunately, they crumbled when being pressed into place.
The Birth of Oilite
Not to be perturbed, Breer joined forces with his associate William Sherwood, an engineering genius, who was at the time involved in the development of the “Cutless Bushing”. Sherwood hypothesised a new method to make powdered metal bearings, that if successful would be far stronger than the GM bushings. Chrysler hired Sherwood immediately and added leading metallurgist Bill Caulkins to the team. After a few months they were able to compress powdered copper (88.5%), tin (10%) and graphite (1.5%) in a die to the desired shape under high pressure, then heat treated in a furnace with just enough oxygen for the tin to melt and make a strong bond between the copper particles. The result was, as Sherwood had boldly predicted, a structure of immense strength compared to that of previously available bushings. The new bushings had around 25% porosity by volume. What was so unique about these bearings was that the porous areas could be filled completely with oil by placing it in a high vacuum, submerging it in oil and then allowing the atmospheric pressure to force oil into the pores. The pores were so small they were barely visible to the naked eye, yet they were continuous and afforded a large surface area to retain oil. Wiped dry, they would show no oil on the surface, yet temperature or friction would bring the oil to the surface and reabsorbed when the temperature dropped. Around 25% of the Oilite bearings were oil. This meant that they usually did not require service after installation.
Legacy of Innovation
Breer, Sherwood and Caulkins had not only found a solution to the problem of the slipping clutch in The Chrysler 70, they had stumbled upon a solution that would be used all over the world in a multitude of applications across all sectors for the better part of the next century with absolutely no indication of it becoming redundant any time soon. The Oilite bearing is used in electric motors, aviation cargo systems, escalators, elevators, industrial meters, stage lighting, thermal imaging cameras, medical imaging equipment. The list is almost endless. Breer, Sherwood and Caulkins went on to create all manner of innovations for Chrysler, but none quite so far reaching and still as significant 90 years later as the Oilite self-lubricating sintered bronze bearing. Happy birthday Oilite!