There has been some talk regarding oil and oilless
air compressors.
The oil types have pistons fitted with rings and
use oil in the crankcase to lub them.
The oilless types I have seen have use a piston
fitted to a diaphram. The diaphram is trapped
between the head and the cylinder and held to
the top of the piston via a plate.
The piston is supported by the diaphram and does
not touch the cylinder wall, this is why it does
not need lubrication. The rod is connected to
the crankshaft via a roller or ball bearing.
As far as I know the heads/valves are the same for
both types.
The overhaul of an oil type compressor is much like
overhauling a small engine.
The overhaul of an oilless compress would require
the replacement of the diaphram and the crank
bearing(s).
Howard
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