reference geometry 62 the maximum state of wear of the brake system is thereby indicated fig2 b shows the embodiment shown in fig2 a likewise again from the perspective of the user of the brake system wherein the same features of the brake system have been denoted by the same reference designations fig3 a shows an embodiment of the brake system according to the invention in which the indicator unit 8 is not fixed to the carrier unit 2 but rather is merely displaced by the carrier unit 2 along an indicator path a the indicator unit 8 is in this case preferably guided on the reference unit 6 wherein a displacement of the indicator unit 8 relative to the reference unit 6 transversely with respect to the indicator path a is not possible the advantage of this embodiment is that the indicator unit 8 can be of much simpler design wherein the preferably bolt like indicator element 82 has a corresponding clip mechanism by way of which the indicator unit 8 can be easily pressed into the reference geometry 62 in the form of a cutout of the reference unit 6 and is subsequently displaced during operation of the drum brake by the carrier unit 2 wherein the.