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

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

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

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

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

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

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

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)

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

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

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

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

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.

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

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 12 500 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 12 500 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!!!

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.

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

Retarder Control Systems Electronic Control Hand Control Foot Control

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