Intarder
Safe Braking
Efficiency counts when you are transporting goods. You need the right engine and transmission for the job. And safety is just as important. The brakes have to work just as well as the engine!
To protect the brakes from fading due to long-term stress, secondary retarders handle much of the work (80 to 90 percent). The service brakes, therefore, remain cool and are ready for use when the occasion arises. In contrast to retarders made by other manufacturers, the Intarder is integrated in the transmission. Gentle brake modulation is made possible by five brake levels. Its compact design causes almost no change to the transmission dimensions.
- The latest version of the ZF transmission brake generates 25 percent more braking efficiency, weighs less, and operates much quieter than its predecessor.
- The new Intarder can be connected to manual as well as automatic transmission systems in a much easier way and is optimally integrated in the vehicle´s brake management system including the cruise control function.
- The Intarder is in charge of both, transmission cooling and heating functions. Thanks to its active support, the required transmission fluid temperature is reached much faster and thereby, also the optimum efficiency ratio for fuel consumption.
- The Intarder is available for manual ZF synchromesh transmissions and automatic AS Tronic transmissions.
- Hydrodynamic, wear-free hydraulic retarder
- Braking is independent of engine speed
Additional Information
System design:
The Intarder is a hydrodynamic and thus wear-free operating hydraulic retarder. Oil is used as an operating medium. The system unveils its brake force at the transmission output.
This principle has the advantage that the brake force generated becomes effective directly at the transmission's output shaft and, via the articulated shaft, at the vehicle's wheels. Also while the driver is shifting, the Intarder remains consistently active and efficient.
The Intarder's main components are:
- the step-up-gear (1)
- the stator and the rotor (2)
- the hydraulic control unit with the solenoid valves (4/5/6)
- the adjustable hydraulic pump
- the stainless steel heat exchanger (3)
- the electronics
And this is how the ZF-Intarder works:
Inside the Intarder, the blade wheels of the rotor and stator are facing each other.
The rotor is connected to the output shaft of the transmission by the step-up stage. It is propelled by the stage with twice the speed of the transmission output.
When actuating the Intarder, oil flows into the retarder chamber. The rotor accelerates the oil and triggers its gyration. In the course of flowing through the chamber, the oil gets to the stationary blades of the stator where its flow is re-directed and led back to the rotor. As a result of the rotor blade circulation, torque is generated which counteracts the rotor's direction of motion. This brake torque is transferred back to the transmission output via the step-up stage and thus, to the driveline. The vehicle is decelerated.
The braking energy created in the process is converted into heat energy which, by means of the heat exchanger, is dissipated to the vehicle engine's cooling circuit.
A powerful hydraulic pump supplies the required oil quantity to the Intarder. It guarantees short response and fill times.
One of the special features of the ZF-Intarder is that the oil circuit is shared with the transmission. Therefore, external tubing or different oil grades for transmissions and Intarder units are not required.
Control unit
The basic principle of the Intarder control unit is always comparable:
Either the electric brake step switch or, linked to the service brake, the Intarder is activated.
Control is effected via an electronic control unit which receives and processes various signals (speeds, temperatures).
The proportional solenoid valve (6) for the hydraulic control unit (4) and the switching valve (5) are activated by the signal from the control unit.
During braking,
the oil circulates directly between the Intarder and heat exchanger.
In order to protect the engine from overheating, the Intarder is equipped with a power-output limit. Depending on the currently measured coolant temperature, braking power is automatically adapted to the available cooling capacity of the engine's heat exchanger.
If the Intarder is switched off,
the hydraulic pump directs the oil from the transmission directly through the Intarder's heat exchanger. This avoids peaks in transmission temperature and, on average, a considerably lower oil temperature is attained. All in all, this leads to reduced oil aging.
