1,027,890. Adjusting vehicle height. F. S. ALLINQUANT. Nov. 13, 1963 [Dec. 5, 1962], No. 44925/63. Heading B7D. In a vehicle suspension including an electrically controlled levelling system which comes into operation only upon closure of a switch 12 actuated by depression of the accelerator pedal 13 of the vehicle, a re-feed relay 15 ensures that any necessary correction of level is completed despite the opening after a predetermined interval of a delayed action relay 14 which otherwise limits the time during which the control circuit is energized. Upon closure of the switch 12 current supplied by a battery 10 flows through a main switch 11 and the delayed action relay 14 to a height-detecting switch 9 which, according to the height of the vehicle body relative to a wheel 2, may energize either an electrically actuated valve 6 controlling admission of gas to a chamber 4 in an oleopneumatic suspension unit 1 from a chamber 5, or the winding 23a of a relay 23 supplying the motor 8 of a piston or gear-type compressor 7 which transfers gas from the chamber 4 to the chamber 5. Conductors 22a, 22b, 22c connect the winding 21 of the re-feed relay 15 and the supply lines to the valve 6, the compressor 7 and any other valves or compressors (not shown) associated with the system whereby the relay 15 is closed whenever a levelling operation is in progress and the delayed-action relay 14 is by-passed. Diodes 24 ensure that current flows in the connections 22a, 22b, 22c only towards the winding 21 thereby preventing unintentional operation of the valve 6 or compressor 7. Indicator lamps such as 6a may be illuminated when the valve or the compressor is energized.