Abstract: In rotors and guide wheels of a turbine engine which are equipped with a shroud ring, at least one opening (26, 28) is provided in the shroud ring (12) in the vicinity of the compression side (A) of each turbine blade (10) in accordance with the invention, in order to reduce gap and peripheral losses. As a result of the prevailing pressure difference, a portion of the flow medium is blown out of the blade channel through these openings into the chamber (22) formed between the sealing combs (16, 18) of the labyrinth seal; this portion would otherwise result in the known problem of peripheral losses in the blade channel. The pressure compensation thus attained between the space preceding the cascade and the chamber (22) blocks off the leakage flow about the outer rim of the shroud ring (12) and thereby precludes the known problem of gap losses as well.