A brake for a trolley that can brake rotation of a trolley wheel only in one direction. The brake includes a support connectable with a frame of the trolley, a first axle connected with another end of the support and peripherally provided with three indents, a pivotal first handle with a detent, wherein the first handle on the first axle can assume three positions defined by the three indents, a pin connected with the first handle and arranged parallel to the first axle, an eccentric ring with a recess, through which the pin projects, wherein the eccentric ring is pivotally mounted on the first axle and can engage with the outer periphery of the pulley wheel, a tension spring connecting the inner periphery of the eccentric ring and the pin, and a stop element projecting from the first axle, which can lean against the inner periphery of the eccentric ring. The brake enables unidirectional braking of a trolley either in forward movement or in rearward movement.
