OIL SOAKED WOOD
BEARINGS
HOW TO MAKE THEM AND HOW THEY PERFORM
Introduction
The purpose of this Technical Brief is to provide some background information for both
constructors and designers who wish to use wood bearings. The type of wood to use, its
treatment, lubrication, and expected performance will be discussed.
Some advantages of oil-soaked wood bearings
Made from locally available materials.
Made by local craftsmen with woodworking skills.
Easily assembled.
Do not require lubrication or maintenance.
Operate under dirty conditions.
Easily inspected for wear.
Quickly repaired or replaced.
Can provide a temporary means of repairing a more sophisticated production bearing.
Require low tolerance on both the shafts and the housings.
Choice of wood
The composition of wood is very complex, but in simple terms it consists of fibrous material
bound together with a glue-like substance, water, resins, and oils.
Initial Selection
D. A. Atkinson (1972) stated that one of the essential characteristics to look for in the choice
of wood is hardness.
The harder the bearing surface, the less the deformation and the smaller the coefficient
of friction.
The harder the bearing surface, the lower the rate of wear.
The harder the bearing surface, the less likely it is to breakdown prematurely, singe, and
ultimately burn.
The harder the bearing surface the greater its strength.
It is also worth noting that generally, the harder the wood, the greater its weight and the more
difficult it is to work.
The oiliness of the wood is a particularly important consideration when the bearings are
unlikely (or not intended) to receive lubrication during their service. Practical indicators that
assist the identification of timbers which may have good self -lubricating properties are:
they are easily polished
they do not react with acids
they are difficult to impregnate with preservatives
glue does not easily stick to them
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