1. RETARDERS

2. 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

3. Advantages - High braking force - Constant speed where needed - at
high speeds
Relieving the driver -
less distraction from
traffic
- Constant speed
for downhill
travels - just
select!
- No interruption of
braking force
when shifting -
meaning active
safety
- Smooth
engagement -
without jerks
- Independent from
speed - adaptation
of braking force
without shifting 1

4. Advantages More safety high braking force Short payback time
High braking force at high speeds.
- Permanent braking
- Adaptation braking
high
VR 3250 and
engine brake
More safety
high braking force
Short payback time
E = 1/2 mv2²
Possibility of increased average speeds with
more safety -
reduced transport times.
Retardation [%]
VR 3250
low
Engine brake
low
high
Speed [km/h]
high
0,5
0,4
0,2
0,1
E = 1/2mv2 means - when doubling the speed, four times the kinetic energy must be dissipated into heat.
Friction coefficient µ
(brake lining
Wear factor
Temp. of brake lining [°C]
low
low
high 1

5. Retarders Types Hydrodynamic Retarders Electrical Retarders
Physical concept:
Torque converter
Electrical Retarders
Foucault current

6. Retarder function Click here Retarder off Retarder on Partial filling
Max. filling
Click here

7. 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.

8. 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

9. Study Example Integrated in to the Volvo gearbox for Volvo trucks
FH and FM
Transition from General Part Voith / Voith Retarder to Volvo VR3250

10. Position of Voith Retarder at Volvo
FH12
Volvo Truck
FM12
Volvo gearbox
 VR 3250
FM9
B12
All new projects / products at Volvo Truck and Bus have one company developing and supplying a Retarder -> Voith
ZF gearbox
 VR120-3 B7
Volvo gearbox
 VR 3250
Volvo Bus

11. VR 3250 Volvo Compact Retarder
RET-TH
(nameplate)
gearbox oil
engine oil
lubrication
transfer
of energy
3 names – one product
VR 3250 = Volvo (Voith?) Retarder; 3250Nm
Volvo Compact Retarder = name known best within Volvo
RET –TH = Retarder Truck Hydrodynamic, designation on the nameplate
Explanation of main components and their respective function
Retarder housing
Oil sump
Step-up
Rotor
Stator
Heat exchanger assembly
Separation of gearbox oil (function ‘lubrication’) and “Retarder oil” (function ‘energy source’)
High utilisation of Retarder oil as energy source = optimum braking force
No charge of gearbox oil (gearbox oil = lube oil)

12. Heat transfer 2 1 3 6 engine gearbox 4 5
The operating medium (oil) in the heat exchanger transfers the braking energy produced to the cooling water.
For protection of engine and Retarder, the Retarder
oil temperature and the
cooling water temperature
are monitored continuously.
1 Thermostat
2 Radiator
3 Fan
4 Heat exchanger
5 Temperature sensor
Retarder oil
6 Temperature sensor
water
Integration of Retarder in the cooling system + explanation of heat dissipation. 1

13. VR 3250 Integrated in to the VOLVO gearbox step-up Volvo gearbox
oil supply not dependent on the gearbox
rotor
Main components (rotor/stator) + step-up (drive wheel + pinion shaft; ratio 2.03:1)
Optimum adaptation of Retarder to the very limited installation space available in the chassis
One Retarder for all applications in the Volvo truck
Identical Retarder assembly for truck and bus (same article number)
Two different heat exchanger assemblies (different water flow) for truck and bus
Standard PTO’s can be used
stator
propshaft
heat exchanger

14. VR 3250 Integration the Retarder ECU
Integration of
Retarder ECU
in the vehicle management
1 Display
2 Retarder sequence switch
3 Cruise control operation
4 RECU (Retarder ECU)
5 Retarder
Fig. 1:
Arrangement of components in the vehicle (VR3250, RECU, Retarder sequence switch, ...)
Operating concept + control (ECU’s) => Volvo’s development
Complete integration of Retarder control in the vehicle management
Diagnostic via Volvo’s diagnostic system VCADS Pro
Fig. 2:
VECU: Vehicle-ECU (VECU) calculates/supplies the required Retarder braking torque from the ECU (Retarder-RECU)
RECU: Retarder-ECU converts the required braking torque into the relevant prop current (closed loop with feedback of existing Py); temperature monitoring by means of 2 temperature probes (water + oil)
Fig. 1:
Arrangement of components

15. VR 3250 Operation and driving mode
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

16. 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. !
Note: For the operation of “additional brakes” (to Volvo’s understanding, this also applies to the Retarder), Volvo specify an engine operation within the “blue range” of the tachometer.
The fuel consumption is not influenced by the high engine speed since the injection system does not supply in overrun condition.

17. Operation and driving mode
Vehicle handling in case of unsafe road conditions
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.
Snow/ice
Swerving hazard
Aquaplaning 1

18. Additional braking systems available at Volvo
VEB
= Volvo Engine Brake; Combination of EPG and VCB
FM 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 Compression
brake) as “individual component” only available
for the FH PS turbocompound engine
= Exhaust brake (Exhaust Pressure Governor)
FM and FH series (standard)
EPG
+ EPG
= Volvo Compact Retarder + exhaust brake
+ VCB
= Volvo Compact Retarder + Volvo Compression Brake
only available for the FH PS turbocompound
engine
Terms “EPG” (exhaust flap) and “VCB” (valve-controlled engine brake)
VEB is the combination of EPG + VCB.
VR3250 combined with VEB is available now (so far only VR3250 combined with EPG)
New 500 HP engine (Turbo Compound Engine) without VEB
Scania patent protects the arrangement turbo charger – turbo compound – exhaust flap)
Thus, more Retarders are needed for this engine design
On presentation of the new FH12 in Malaga, the press vehicle was equipped with the VR3250!!!

19. 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.

20. 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.

21. 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.

22. In the transmition line
Location
Fix directly to gearbox
In the transmition line

23. Retarder Control Systems
Electronic Control
Hand Control
Foot Control

24. Comparative Electrical Cheaper Easy to install
Ratio decreases 10%-20% by heating
Hydrodynamic
Lighter
Cooling system quicker
Slower at the begining
More used