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Turbocompressor
DH10A, 245, 285
To exhaust
system
To intercooler
From air
cleaner
Open
Closed
From exhaust
manifold
The turbocompressor on engine DH10A, 245 and 285,
has a wastegate function that limits charge pressure at
high power output. The wastegate-shutter functions as
a by-pass valve for the exhaust turbine. The shutter is
activated by a pressure box that, together with a hose
connection, senses the charge pressure in the compres-
sor housing.
At low charge pressure, the pressure box spring keeps
the shutter closed with a control rod. When the charge
pressure reaches the pressure box opening pressure, the
shutter starts to open to by-pass the exhaust pressure
directly to the exhaust pipe. This offloads the exhaust
turbine and the turbo speed drops.
The above function provides the turbocompressor with
a broader working range and this results in an engine
characteristic that has a wide high torque range and a
limited charge pressure at full power output.
The turbine shaft journalling is lubricated and cooled
by the engine pressure-lubricating system. Since en-
gine DH10A, 245 and 285, is a typical city bus engine,
which often has sound encapsulation, the bearing hous-
ing is moreover cooled by a coolant feed connected to
the engine cooling system. Oil supply is essential to the
function of the turbo compressor. That is why it is
vitally important that the engine lubricating system is
maintained according to instructions and that lube oil
of the right quality and viscosity is used.
