24A AUXILIARY EQUIPMENT
General description
The Wabco 159 or 229 compressor is fitted to a
drive assembly which is fitted to the rear face of the
timing case on the left side of the engine. The drive
assembly has two gears of equal size on a common
shaft. The forward gear is driven by the engine idler
gear and the gear at the rear of the drive assembly
drives the compressor gear.
Later Wabco 159 and 229 compressors were
introduced, together with a new compressor drive
assembly which will enable the timing of the new
compressor to the engine. This reduced the noise
from the compressor and gears. The later
compressors can be used with the earlier
compressor drive if the earlier compressor drive
gear is used, but the compressor timing cannot be
matched to the engine.
The latest engines, fitted with a compressor, have
either a Bendix 1W150R or 1W250R. The Bendix
compressor is fitted on the left side of the engine
directly onto the rear face of the timing case. The
compressor is driven from the main idler gear
through an idler gear for the compressor.
The cylinder head of the single cylinder compressor
is cooled by coolant from the engine. The
compressor is lubricated from the lubrication
system of the engine. Oil passes through a pipe
from the engine pressure rail to the compressor
crankcase. The oil passes to the main bearings and
the big end bearings of the compressor and also to
the rear bush for the drive shaft. Oil which drains
from the compressor crankcase into the drive
housing, lubricates the drive gears and the bearing.
The oil returns to the engine sump through the
timing case.
Operation
As the piston moves down the cylinder, air pressure
above the piston is reduced. The reduction in air
pressure opens the inlet valve and allows air to
enter the cylinder above the piston. As the piston
moves up the cylinder, air pressure under the valve
and the action of the valve spring, closes the valve.
The increase in air pressure under the delivery
valve, opens the valve and air is discharged to the
reservoir. Air pressure in the reservoir is controlled
by an unloader valve which, at a certain pressure,
holds the inlet valve of the compressor open until
air pressure in the reservoir is reduced.
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PA283
PA069
24A.02 Perkins Phaser/1000 Series, April 1995
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