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