AN IMPORTANT MATTER

Rotorua Morning Post, Volume 2, Issue 338, 27 September 1932, Page 2

AN IMPORTANT MATTER

HEADLAMP EFFICIENCY. The importance of maintaining perfect electric contacts tliroughout the headlamp circuit in a motor-car is not always recognised by car owners. The average modern headlamp bulb di*aws a current of four or six amperes at six volts. If such a current be applied to a contact point which is not perfect, and which therefore presents considerable resistance to its passage, a drop of voltage occurs across the point, and the pressure available to light the

lamp is therefore reduced. . This in | turn produces a dimming of the light > similar to that which follows the us'e of a badly "run down" battery. Moreover, a poor contact will become progressively worse, because ' the power lost at the contact is disipated as heat, which promotes corrosion of the points concerned, and may be sufficient to impair the strength of spfings in the contacts. There are two points in the headlamp circuit in which pressure contacts ar'3 employed, and in which trouble may develop. The first of these is in the bayonet sockec, which the contact studs of the socket are held against the lamp base by springs, and the second is the lamp | switch, where some form of spring | or spring-loaded aim bearn u;on a contact. Both these poinls should ! oeeasfonally be inspected, and if 1 found to be dull should be burnished j with sandpaper. Usually the operation ! of the- switch will keep the switch con- ; tacts clean, but the pressure of the spring contact may be impaired, and it should be adjusted occasionally.