Patent ID: 8257047

Claim:
A rotor blade fittable on the rotor of a turbomachine, the rotor having a circumferential slot in an outer periphery of the rotor, the slot including undercuts, the slot including circumferentially adjacent spacers having retaining surfaces which, in the direction of a blade axis, are engageable with surfaces in the slot undercuts, the rotor blade comprising: a blade airfoil having a lower end; a blade root, adjoining the lower end of the blade airfoil and extending along a blade axis, retainable between two of the spacers, wherein the blade root includes a T-shape cross section and circumferentially extending shoulders, the shoulders configured and arranged to fit under adjacent spacers, wherein the T-shaped blade root is formed by milling; and a relief groove at transitions of the blade root to the shoulders extending in the direction of the blade axis, for reducing mechanical stresses.