Patent ID: 6923255

Claim:
An activating ball assembly for use with a by-pass tool incorporated in a drill string, said tool having: a through-flow housing through which drilling mud can flow when the tool is deactivated; a control sleeve movable lengthwise of the tool between a through-flow mode and a by-pass mode; a by-pass port in the tool through which mud can flow when the sleeve is in its by-pass mode; and, a valve seat which is engageable by the activating ball assembly in order to move its sleeve to its by-pass mode and thereby divert the mud from flow through the housing to by-pass flow through the by-pass port; and in which the activating ball assembly comprises: a deformable ball of a size sufficient to engage and to be held captive by the valve seat; and a weight attached to the ball and operative to assist in movement of the assembly under the action of gravity to engage the ball with the valve seat, said weight being of smaller transverse dimensions than the ball so as to be capable of moving downwardly through the valve seat and to pull the ball into engagement with the valve seat, in which an open ended throughflow passage extends lengthwise of the ball assembly between an inlet end in the ball and an outlet end in the weight, to allow a limited proportion of fluid to continue to flow through the housing when the ball is seated on the valve seat.