Bang start
In the field of automobile testing, a test in which gearboxes , differentials , cardan shafts and drive shafts are exposed to a shock load is called a bang start (English idiot start , also dumping , dropping or sidestepping the clutch according to the type of clutch pedal relief / clutch load).
The test is only used on vehicles with a manual gearbox and a normal clutch pedal .
Test procedure
- The test driver engages first gear or reverse gear, as this is where the strongest torque is generated on the following components due to the reduction.
- The engine is brought to high speed (usually 2/3 to full engine speed).
- The test driver pulls his foot sideways off the clutch pedal.
When the clutch is suddenly engaged, the motor exerts a rotary jolt on the gearbox and all subsequent components of the drive train. This results in a very high load on the drive train.
The torsional shock can be up to three times the engine torque; in commercial vehicles, the front axle can lift off during the test.
scope of application
The test has to be withstood about 10-20 times as part of the vehicle testing (depending on the requirements of the vehicle manufacturer), only a smaller part of the tests is carried out in reverse gear. The vehicle stands with the wheels on dry asphalt ( coefficient of friction µ about 1), and the tests are sometimes carried out with a full load. The brakes are not applied.
When designing the drive train, the cardan shaft is usually defined as the weakest link. So if a break occurs as a result of a bang start, it is easiest to replace it.
Replacement test for automated transmissions
This test does not apply to vehicles with an automated clutch ( automatic transmission , dual clutch transmission , CVT and automated manual transmission), as the clutch control prevents any misuse by the driver.
In older automated transmissions, in which the engine and transmission controls do not work together, the peak load occurred when the vehicle was stationary, at full throttle and at the same time with full braking ("stall torque"). The maximum torque is then passed from the motor via the drive train and supported there again when the brakes are on the wheel.
In newer vehicles, the engine management system detects braking activity and largely ignores the accelerator pedal position. In some cases, the engine torque is also limited in the lower gears so that the peak loads can be further reduced.
Individual evidence
- ↑ Example of the use of the term from the field of clutch testing
- ^ Eckhard Kirchner: Power transmission in vehicle transmissions. Basics of the design, development and validation of vehicle transmissions and their components . Springer-Verlag 2007, ISBN 978-3-540-35288-4