The electric window lifter system includes an endless chain, a driving gear wheel and a driven gear wheel. Both wheels are incorporated in housings with parallel walls, each with a central hole and an annular chain channel surrounding it. Opposite peripheral parts of the walls form a gap between the hole and the chain channel which allows the penetration of the gear teeth into the chain channel. Around the central hole runs a peripheral edge which lies on an annular shoulder of the corresponding gear wheel and supports its movement. Each of the housings has a lip in the area of the inner diameter of the peripheral edge which stretches inwards from here in order to give the corresponding gear wheel some axial pressure.
