High braking efficiency can be obtained by using two concurrent jaws. In this mechanism, each of the jaws is pressed by a separate expander and is suspended on an independent thrust pin. The mechanism with two concurrent jaws ensures full braking performance, but only when driving forward. However, while driving backwards (due to a change in the rotation of the brake drum) the braking efficiency decreases significantly, because both jaws then work counter-rotating. Uneven wear of the linings can be prevented quite effectively by hanging the jaws with sliders. Two sliders are rotatably mounted on the central pin, connected to the jaws by pins. During braking, the linings adhere fairly evenly to the working surface, because the slides can rotate on the central pin, and the jaws may twist in relation to the sliders. Some cars have brake mechanisms with sliding shoes. In this case, the lower ends of the shoes rest against the pin embedded in the brake disc, that the sliding jaws can not only pivot about their fulcrum, but also to move. During braking, thanks to the great freedom of movement, the jaws automatically set themselves in the most correct position in relation to the working surface of the drum. Relatively even contact between the linings and the drum is achieved by the use of eccentric pins in the drum brake mechanism, which, as already mentioned, are used to adjust the play between the jaws and the drum. Please note, that in the double-jaw brake mechanism only approx 2/3 the working surface of the drum is in contact with the linings of the jaws. Better use of the working surface of the drum is achieved by the use of the three mechanism- or four-jaws. A much higher braking performance is thus achieved.