DAF LF45, LF55 Series. Manual - part 307

©

 200416

1-1

Safety instructions

ENGINE BRAKE, BE ENGINE

ΛΦ45/55 series

4

4

1. SAFETY INSTRUCTIONS

1.1 SAFETY INSTRUCTIONS

Fuel

Diesel fuel is an extremely 

flammable liquid, and must not be 

exposed to naked flames or come 

into contact with hot surfaces. The 

diesel fuel fumes remaining in an 

empty fuel tank form an extremely 

explosive mixture.

When fuel system components are being 

removed, some fuel will escape.

To keep this spillage to a minimum, unscrew the 

tank cap to release any overpressure.

Any spilled fuel must be collected, bearing in 

mind the risk of fire.

Exhaust gases
Do not run the engine in an enclosed or 

unventilated area.

Make sure exhaust fumes are properly extracted.

Exhaust gases contain carbon 

monoxide.

Carbon monoxide is a deadly 

colourless and odourless gas, 

which, when inhaled, deprives the 

body of oxygen, leading to 

asphyxiation. Serious carbon 

monoxide poisoning may result in 

brain damage or death.

Moving parts
Remain at a safe distance from rotating and/or 

moving components.

Various fluids
Various oils and lubricants used on the vehicle 

may constitute a health hazard.

This also applies to engine coolant, windscreen 

washer fluid, refrigerant in air-conditioning 

systems, battery acid and clutch fluid.

So avoid inhaling and direct contact.

Electrical short-circuit
Always disconnect the battery's earth connection 

during repair or maintenance operations for 

which the electric power supply is not required.

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ENGINE BRAKE, BE ENGINE

1-2

©

 200416

Safety instructions

4

ΛΦ45/55 series

4

©

 200416

2-1

General

ENGINE BRAKE, BE ENGINE

ΛΦ45/55 series

4

4

2. GENERAL

2.1 LOCATION OF EXHAUST BRAKE COMPONENTS

1.

Exhaust brake valve

2.

Air pipe

3.

Operating cylinder, exhaust brake

4.

Butterfly valve

1

3

4

2

i400858

ENGINE BRAKE, BE ENGINE

2-2

©

 200416

General

4

ΛΦ45/55 series

4

2.2 SYSTEM DESCRIPTION, EXHAUST BRAKE

Note:

The engine brake is an exhaust brake.

Switching on the exhaust brake
The exhaust brake consists of an engine brake 

operating switch fitted to the steering column and 

an operating cylinder (3) connected to the 

butterfly valve (4) in the exhaust pipe.

If the exhaust brake operating switch is activated, 

a signal is passed to the engine management 

system's electronic unit. The operating switch 

has the positions "off" and "automatic". In the 

"automatic" position the engine management 

system's electronic unit engages the exhaust 

brake whenever this is appropriate and possible. 

Of course, the electronic unit disengages the 

exhaust brake when required. 

If the exhaust brake is engaged by the electronic 

unit, the unit energises the exhaust brake valve 

(1), causing supply pressure to flow to the 

operating cylinder. The cylinder closes the 

butterfly valve in the butterfly valve housing. The 

exhaust pipe is then almost completely closed off. 

The engine management system's electronic unit 

also interrupts the fuel supply to the various 

cylinders. The engine now acts as a compressor, 

creating a braking action.

The higher the engine speed, the greater the 

braking action of the engine brake.

Switching off the exhaust brake
If the engine brake control switch is pushed back, 

the butterfly valve will be re-opened and the fuel 

supply to the various cylinders will be re-instated.

1

3

4

2

i400858

1.

Exhaust brake valve

2.

Air pipe

3.

Butterfly valve operating cylinder

4.

Butterfly valve