Patent GB-786684-A (GB)
Title: Improvements in or relating to the automatic adjustment of vehicle head lights
IPC: B60Q1/115
Filed: 1955-10-14
Abstract: 786,684. Vehicle lamps. BOSCH GES., R.Oct. 14, 1955 [Oct. 16, 1954], No. 29275/55. Class 75(3). In a control device acting automatically to changes in the loading of a vehicle to maintain constant the range of the headlights and comprising two relatively displaceable parts 14, 15, one of which 14 is connected to a part of the vehicle for instance the frame 10, which is spring mounted relative to the road and the other 15 to a part of the vehicle, for instance the back axle 11, not spring mounted relative to the road, two oppositely acting springs 18, 20 of different stiffness are provided, the weaker spring 18 engaging at one end on one of the relatively displaceable parts 14, 15 and at the other end on the part of the vehicle associated with that displaceable part whilst the stronger spring 20 engages each of the relatively displaceable parts 14, 15, the difference in the stiffness of the springs being such that the movement of the two parts 14, 15 relative to each other upon change in the loading of the vehicle is only a fraction of the movement of the frame 10 relative to the back axle 11. In Fig. 1 the weaker spring 18 is a helical tension spring and extends between the part 15 and the axle 11, the other part 14 being secured to the frame 10. In another arrangement the weaker spring is a helical tension spring and extends between the part 14 and the frame, the other part 15 being rigidly connected to the axle. In still another arrangement the weaker spring is a pressure spring and is arranged between the axle 11 and the part 15, the other part 14 being secured to the frame 10. In all three arrangements the stronger spring 20 is a pressure spring. The part 14 is a cylinder and the part 15 is a piston of insulating material displaceable in the cylinder. A resistance wire 16 is wound around the piston and a spring loaded pin 17 disposed in a projection from the cylinder 14 slides over the resistance wire to regulate the current from a battery 21 to the exciter windings 25 of two electro-magnets adapted to attract two armatures 24 connected to two headlights 22 pivoted about horizontal spindles 23 on the frame 10 at the front of the vehicle. In the position shown the vehicle is fully loaded. If the vehicle is now unloaded the rear end of the frame 10 rises and the piston 15 moves downwardly in the cylinder 14 and the resistance in the electrical circuit decreases and consequently the armatures 24 swivel the headlights upwardly against the action of springs 26 to offset the forward inclination of the unloaded vehicle. A practical form of the control device is shown in Fig. 4. A sleeve 43 of insulating material is disposed within a cylindrical casing 40 of insulating material and has an end hub 44 adapted to slide on an axial metal bolt 42 secured to the base of the casing. The part of the bolt outside the casing is insulatedly secured to a part 65 of the vehicle. A helical pressure spring 46 is supported with initial tension between the hub 44 and a metal disc 45 detachably secured to the lower end of the bolt. A helical tension spring 53 extends from a groove in the lower end of the sleeve 43 to a plate 54 adapted to be hooked to a part 59 of the vehicle and having a plurality of holes 55 arranged so that the lower end convolutions of the tension spring can be screwed through them to regulate the effective length of the spring. The annular gap 51 between the casing 40 and the sleeve 43 is sealed by an annular diaphragm 52 and air flow through bores 48 in the hub 44 to the annular gap is controlled, to dampen the action of the device, by fine bores 50 in a disc 49 covering the lower end of the sleeve 43. A coil of resistance wire 47 is wound around the sleeve 43 and is connected electrically to the upper end of pressure spring 46 and therefore to the metal disc 45 and the metal bolt 42, the upper end of which is connected to an electric supply. A spring loaded pin 62 engaging the resistance wire is slidably disposed in a lateral extension 60 of the casing 40 and is connected to a terminal 64 on the end of the extension.