Single-axle air suspension: Transposition

The operating mode "transposition" prevents balancing of any inclination when only one wheel of the vehicle drives over an obstacle. Equalization would cause a new inclination after the vehicle is driven off the obstacle, making a new regulation sequence necessary. If the vehicle is driven onto the curbstone and stopped, the EHC control unit will switch from drive mode to normal mode. In this control function, the signals of the ride height sensors on the left and right are evaluated. If the difference in ride height between the left and right sides of the vehicle exceeds a certain amount (e.g. 28 millimeters), switch-over to the control function "skew" takes place.

In this control function, the vehicle ride height in the middle of the axle is evaluated by the EHC control unit. If the vehicle is loaded or unloaded, the degree of rebound is considered. If the figure is outside the defined tolerance band (e.g. ±10 millimeters), modulation is initiated. The left and right-hand sides of the vehicle are raised or lowered by the same amount as each other. The difference in ride height between the two sides is retained.  When the EHC control unit goes into the Drive mode, the control function "transposition" is terminated. Any ongoing control is cancelled. The "skew" control function is cancelled when the ride height difference between left and right sides of the vehicle is below a specified amount.