DAF CF65, CF75, CF85 Series . Manual — part 455

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General

PE ENGINE INLET/EXHAUST SYSTEM

CF65/75/85 series

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2.2 SYSTEM DESCRIPTION, TURBOCHARGER

Wastegate
To make the engine more responsive at lower

engine speeds, a turbocharger is used that

produces a better charge ratio at these speeds.

Without provision having been made for this, the

boost pressure yielded by this turbocharger

would be too high at maximum engine speeds.

Use of a wastegate prevents this.

The turbocharger's compressor housing has an

air coupling connected to a diaphragm. The boost

pressure yielded by the turbocharger operates

the diaphragm and the control rod connected to it.

The control rod operates a valve in the turbine

housing.

The valve in the turbine housing is opened when

the maximum pre-set pressure has been

reached.

When the valve is opened, some of the exhaust

gases will be discharged directly to the exhaust

pipe rather than being used to propel the

turbocharger's turbine wheel.

Compression housing by-pass
At higher boost pressures, the turbocharger

compressor tends to allow this pressure to return

to the intake underpressure area. To prevent this,

the turbocharger's compression housing has

been adapted.

This adaptation consists of bypass ducts and a

stop plate.

Boost pressure attempting to return to the intake

area will do so at the outer circumference of the

compression housing.

The compression housing has been fitted with an

air slot to force this pressure to flow back through

special air ducts on the outside until it is arrested

by the stop plate.

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General

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CF65/75/85 series

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Inspection and adjustment

PE ENGINE INLET/EXHAUST SYSTEM

CF65/75/85 series

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3. INSPECTION AND ADJUSTMENT

3.1 INSPECTING AND ADJUSTING TURBOCHARGER WASTEGATE

1.

Remove the heat shield from the

turbocharger.

2.

Remove the air supply connector (1) from

the diaphragm housing (2).

3.

Remove the retaining clip (3) and remove the

control rod (4) from the wastegate lever.

4.

Using a reducer valve, apply the specified

adjusting pressure to the connection with the

diaphragm housing (see "Technical data").

5.

Push the wastegate lever (5) fully to the left

to close the wastegate valve.

6.

Adjust the length of the control rod (4),

making sure it fits exactly onto the lever at

the set pressure.

7.

Inspect the adjustment of the wastegate

using the specified pressure. See "Technical

data".

8.

Fit the retaining clip (3).

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Inspection and adjustment

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CF65/75/85 series

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3.2 CHECKING EXHAUST GAS BACK PRESSURE

Checking exhaust gas back pressure
1.

Remove the plug from the exhaust bracket

and install a suitable coupling with a pipe.

The first part of the pipe must be made of

metal, to withstand the high temperatures.

2.

Connect a pressure gauge to the pipe, with a

range of at least 0.1 - 0.2 bar (10 - 20 kPa).

Note:

Use an attenuated gauge to prevent

excessive shaking of the gauge needle.

The engine brake must not be used during

measurements.

This is to protect the pressure gauge.

3.

Measure the exhaust gas back pressure at

full-load engine speed and compare the

measurement to the specified value; see

"Technical data".

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