Abstract: A drive power transmission element in the form of a wheel adapted to be mounted non-rotatably on a shaft or axle in which the wheel has a peripheral surface provided with a unique groove receiving a flexible power transmission element, such as a rope, in which the groove is provided with a plurality of circumferentially spaced impressions which are radially and circumferentially curved in configuration and which taper or converge on the line of circumference rather than along the radii of the wheel.