Johdejarru

A guide-rail brake (1) of an elevator and a method for controlling the brake are provided. The brake comprises a frame part fixed to the elevator car, a prong part, which contains turning jaws (3,4) that correspond to the guide rail (2) via the braking surfaces when braking, a spring (10) loading the prong part to press the braking surfaces to the guide rail, and a controllable mover, which is an electromagnet (15), which contains two pulling core pieces (17,18). The force effect of the electromagnet (15) on the prong part is opposed to the spring. In the guide-rail brake an air gap (ag) is structurally arranged between the center parts (19,20) of the pulling core pieces (17, 18) of the electromagnet of the guide-rail brake when the brake is fully energized, and a damping circuit is arranged in the coil (16) of the electromagnet (15) of the guide-rail brake to speed up operation of the guide-rail brake.