
82 LIGHT AND HEAVY VEHICLE TECHNOLOGY
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Figure 4.6 Hydrostatic lubrication
Boundary lubrication
during starting
Hydrodynamic lubrication
during normal running
Figure 4.7 Mixed-film lubrication in journal bearing
4.3 ENGINE LUBRICATING OIL
The origins of petroleum
Lubricants can be produced from animal, vegetable
and mineral oils; it is the last of these, refined from
petroleum and treated with additives, that are suitable
for the lubrication of motor vehicle engines. Petroleum
is generally thought to have been formed by the de-
composition of tiny marine organisms that died, sank to
the bottom of the sea and became mixed with sediment ...