The rail mounted displaceable device is a ceiling mounted hoist comprising two pairs of carrying wheels (2) arranged to run in the rail (1) and two motion wheels (4) actuated by a motor (7). The motion wheels (4) are rotatably fixed on a hinged bracket (5) a hinge (6) to a chassis (3). The displaceable device is provided with an actionable solenoid (8) for pressing said transport wheels (4) against the rail (1) in order to allow a displacement of the device along the rail (1) when the motor (7) is activated and to allow the carrying wheels (2) to rotate freely along the rail (1) when said motor (7) is deactivated.