RETARDERS

Retarders

Retarder can reduce the speed of the vehicle but CANNOT stop totally.

Braking torque is zero with the vehicle without movement.

Kinetic Energy Thermal Energy

- High braking force where needed - at high speeds

Relieving the driver -less distraction fromtraffic

- Constant speed for downhill travels - just select!

- Smooth engagement - without jerks

- Independent from speed - adaptation of braking force without shifting

- No interruption ofbraking forcewhen shifting -meaning activesafety

Advantages

E = 1/2mv2 means - when doubling the speed, four times the kinetic energy must be dissipated into heat.

Possibility of increased average speeds withmore safety - reduced transport times.

High braking force at high speeds.- Permanent braking- Adaptation braking

More safetyhigh braking force Short payback time

VR 3250 and engine brake

Speed [km/h]

Ret

ard

atio

n [

%]

E = 1/2 mv2²

VR 3250

Engine brake

low

low high

low

hig

h

Temp. of brake lining [°C]

0,5

0,4

0,2

0,1Wea

r fa

cto

rlow high

hig

h

Fri

ctio

n c

oef

fici

ent

µ(b

rake

lin

ing

Advantages

Retarders Types

• Hydrodynamic Retarders– Physical concept:

Torque converter

• Electrical Retarders– Physical concept: Foucault current

•Retarder off•Retarder on

– Partial filling

– Max. filling

Retarder function

Click here

Example: Voith Retarder 115

Components • 100 Bastidor del retarder• 2900 Tanque de aceite• 3300 Intercambiador de calor• 3700 Válvula proporcional• 5900/1 Sensor de temperatura de líquido de refrigeración. • 5900/2 Sensor de temperatura de aceite.

Ejemplo: Voith Retarder 115

Electrical diagram• 100 Retarder chassis• 2900 Oil reservoir• 3300 Heat exchanger• 3700 Proportional valve• 5900/1 Cooling system temperature sensor• 5900/2 Oil temperature sensor

Integrated in to theVolvo gearbox forVolvo trucksFH and FM

Study Example

Position of Voith Retarder at Volvo

B12

B7

FM9

FM12

FH12Volvo Truck

Volvo Bus

Volvo gearbox VR 3250

Volvo gearbox VR 3250

ZF gearbox VR120-3

RET-TH(nameplate)

gearbox oil engine oil

lubrication transfer of energy

VR 3250 Volvo Compact Retarder

The operating medium(oil) in the heatexchanger transfersthe braking energyproduced to thecooling water.

For protection of engineand Retarder, the Retarderoil temperature and thecooling water temperatureare monitored continuously.

1 Thermostat2 Radiator3 Fan4 Heat exchanger5 Temperature sensor

Retarder oil6 Temperature sensor

water

2

1

3

6

enginegearbox

4

5

Heat transfer

Integrated in to the VOLVOgearbox

heat exchanger

rotor

stator

step-up Volvo gearbox

propshaft

oil supply notdependent onthe gearbox

VR 3250

Integration ofRetarder ECUin the vehiclemanagement

Fig. 1:Arrangement ofcomponents

1 Display2 Retarder sequence switch3 Cruise control operation4 RECU (Retarder ECU)5 Retarder

VR 3250 Integration the Retarder ECU

Standard position Retarder sequence switch Step A:Steps A:-When actuating the brake pedal, the Retarder will be activated automatically (Retarder blending).- The function “constant speed”can be activated via the tip switch.

Steps 1-3:- Manual Retarder braking steps

Step B:-Step B = max. braking force.- Stage B is only available in vehicles with automatized gearbox (I-Shift, Geartronic).-The "braking programme" is activated by actuating stage B. The Retarder sequence switch returns from stage B to stage 3. On activation of the braking programme, the gearbox selects the speed where the additional brake is effective best.-The braking programme can be deactivated by shifting down from stage 3 or by applying the accelerator pedal

VR 3250 Operation and driving mode

!

Driving mode at temperature limitation

If possible, shift down when braking with Retarder.

Goal: high engine speed

Thus:- High delivery of water pump- High fan speed

Result:- The Retarder efficiency can fully be used.

The fuel consumption is not influenced by the high engine speed since the injection system does not supply in overrun condition.

Operation and driving mode

Vehicle handling in case of unsafe road conditions

Snow/ice

Swerving hazard

Aquaplaning

- In case of bad road conditions, actuate the

retarder carefully and step by step.

- In extreme cases do not switch on the retarder. Please observe this precaution particularly for vehicles without ABS!

- On account of the total system, the retarder is switched off delayed in case of ABS function.

When ABS is switched off, the retarder will

become effective again.

Operation and driving mode

VEB = Volvo Engine Brake; Combination of EPG and VCBFM and FH series (option)> not for the 500 PS turbocompound engine

= Volvo Compact Retarder + Volvo Engine Brake FM and FH series

VR3250 + VEB

VCB = Valve-controlled engine brake (Volvo Compressionbrake) as “individual component” only availablefor the FH 12 500 PS turbocompound engine

= Exhaust brake (Exhaust Pressure Governor)FM and FH series (standard)> not for the 500 PS turbocompound engine

EPG

VR3250 + EPG

= Volvo Compact Retarder + exhaust brake FM and FH series (option)

VR3250 + VCB

= Volvo Compact Retarder + Volvo Compression Brakeonly available for the FH 12 500 PS turbocompound

engine

Additional braking systems available at Volvo

Electrical Retarders

The electrical retarders are based on the use of Eddy of Foucault currents which are created in metallic solid masses when turning within a uniform magnetic field.

Electrical Retarders

It is made up of two parts:Stator: static part equipped with a set of electric coils.Rotors: turning parts that absorb and dissipate the kinetic energy of the braked system.

Electric current create magnetic fields when passing through the coils.

Electrical Retarders

When rotors turns inside the magnetic fields, Eddy currents appear.Eddy currents create forces opposing to the movement of rotors.

Kinetic energy is transformed into heat in the rotors and dissipated through their vanes.

Retarder Control Systems

Hand Control Foot Control

• Electronic Control

Comparative

• Electrical– Cheaper– Easy to install– Ratio decreases 10%-20% by heating

• Hydrodynamic– Lighter– Cooling system quicker– Slower at the begining– More used