ASSYRIA - Around 700 B.C. logs were placed under heavy loads, which allowed them to be rolled over the logs. This is a true example of anti-friction, rolling action. This is considered an example of what is known today as a linear bearing.

BATTERING RAM - This is an early example of a linear bearing. The battering ram rides back and forth on rollers placed in “roll tracks." This was a Greek design of around 330 B.C. Note that the input is through the roller “carrier”. This doubles the speed and momentum of the ram.

CART & AXLE - The wheel and axle was in common use by this time. The “bearing” is just wood on wood. It’s likely that lubrication of some kind was used (probably animal fat oils). The axle would eventually wear to the point of breaking. It required a lot of effort to pull it.

CART II - Between 300 and 100 B.C., the Celtics used a cart similar to this. It used metal axles and hubs but also used a full set of cylinder shaped rollers made of wood. True Anti-Friction design. The cart was easy to pull, however, it had a low weight capacity due to the rollers being wood.

BALL BEARING DEVELOPMENT - Grooved channels were used with balls for ball bearings. The groves and metal balls lead to the more common ball bearing. Many variations were developed. The bicycle’s need for low friction prompted much of the development during this time. The Industrial revolution lead to further development and common usage. In the 19th century balls were cut from steel rods and machined manually on lathes. However, under heavy loads, this "inaccuracy" caused the bearing to run unevenly.

SPINDLE - A major innovation towards designing a long wearing bearing was the use of metal sleeves and axle spindles. This allowed the size of the bearing to be reduced. The smaller radius and surface area involved makes this arrangement easier to turn (lower torque). This is the beginnings of “plain” bearings (The same type of bearing used in a car engine. They perform well when run at a high speed with a pressurized layer of lubricant.).

RAILROAD FRICTION BEARING - The evolution of the friction bearing in the railroad industry. These were mounted in journal boxes where lubrication could be continuously fed and most dirt and water were kept out. Origin of the term ‘hot box’ detector. These were popular until the late 60’s when conversions to anti-friction were popular. AAR rules no longer allow their use in interchange service. Requires high maintenance. High friction.