1285586 Correspondence control systems ROBERT BOSCH GmbH 31 Oct 1969 [31 Oct 1968] 53410/69 Heading G1N The inclination of the headlamps of a road vehicle is automatically adjusted in accordance with the inclination of the vehicle body relative to the road by a control circuit comprising pickups 18, 19, Fig.1, responsive to positions of front and rear axles relative to the vehicle body to provide a signal αs representing the inclination of the vehicle body relative to the road, a pick-up 14 responsive to the inclination of a headlamp 10 relative to the vehicle, and a bi-metal member 13 for adjusting the inclination of the headlamp 10 in accordance with an error signal #α derived at a summing point 16. The pick-ups may be in the form of resistive or inductive voltage dividers having tappings or iron cores displaceable in accordance with the loading of the axles. In Fig.5 (not shown) the iron core (58) of an inductive voltage divider is connected via a weak spring (53) to the axle and a strong spring (52) to the body. The pick-ups are differentially connected, Figs.2 and 3 (not shown), so that equal loading of both axles produce no nett output. Amplifier 15 is arranged to produce a pulsating output of a mark space ratio proportional to the integral of the error signal. In one arrangement Fig.4 (not shown) a temperature compensating diode (D2) compensates for variations in the threshold voltage of the input transistor (T1). In Fig.6, inductive pick-ups 66, 67 for axle loading and inductive pick-ups 68, 69 for headlamp inclination are connected via polarity determining diodes to summation networks at the inputs of two amplifiers 15. Permanent steady state inputs UK are supplied to the amplifiers 15 for providing a standing heating current to the bimetal members 13 for keeping the headlamps in their neutral positions, and may be derived from oscillator 70 via diodes (not shown).