Torque-transmitting tool assembly

A tool assembly for transmission of an externally applied torque, comprising:

• a tool member comprising:
• a shank element, longitudinally rotatable about a tool axis, for receiving an externally applied torque;
• a first tier element, rotatable with and supported by the shank element and having invariant cross-section along the tool axis, comprising:
• a first torque section, comprising:
• first and second side surfaces, spaced from and extending radially inward in relation to the tool axis, the first and second side surfaces subtending a predetermined angle with respect to the tool axis;
• a riser surface extending longitudinally with respect to the tool axis, and extending laterally between the first and second side surfaces;
• and
• a step surface extending perpendicularly to the tool axis and inwardly from the riser surface, while remaining spaced from the tool axis;
• and
• a second torque section, comprising:
• first and second side surfaces, spaced from and extending radially inward in relation to the tool axis, the first and second side surfaces subtending the same predetermined angle, relative to the tool axis, as that subtended by the first and second side surfaces of the first torque section;
• a riser surface extending longitudinally with respect to the tool axis, and extending laterally between the first and second side surfaces;
• and
• a step surface extending perpendicularly to the tool axis and inwardly from the riser surface, while remaining spaced from the tool axis;
• and
• an apex element, supported at a position on the tool axis more distant from the shank element than the first operating element, rotatable with the shank element, and having an invariant cross-section along the tool axis, comprising:
• a first torque section, comprising:
• first and second side surfaces, extending radially inward in relation to the tool axis, the first and second side surfaces subtending the same predetermined angle, relative to the tool axis, as that subtended by the first and second side surfaces of the first torque section of the first tier element, with the first side surface coplanar with the first side surface of the first torque section of the first tier element, and with the second side surface coplanar with the second side surface of the first torque section of the first tier element;
• a riser surface, extending longitudinally with respect to the tool axis, and extending laterally between the first and second side surfaces, the riser surface having an average distance from the tool axis which is smaller than the average distance of the riser surface of the first tier element from the tool axis;
• and
• an apex surface extending perpendicularly to the tool axis and extending inwardly from the riser surface, while remaining spaced from the tool axis;
• and
• a second torque section, comprising:
• first and second side surfaces, extending radially inward from in relation to the tool axis, the first and second side surfaces subtending the same predetermined angle, relative to the tool axis, as that subtended by the first and second side surfaces of the second torque sections of the first tier element, with the first side surface coplanar with the first side surface of the second torque section of the first tier element, and with the second side surface coplanar with the second side surface of the second torque section of the first tier element;
• a riser surface, extending longitudinally with respect to the tool axis, and extending laterally between the first and second side surfaces, the riser surface having an average distance from the tool axis which is smaller than the average distance of the riser surface of the first tier element from the tool axis;
• and
• an apex surface extending perpendicularly to the tool axis and extending inwardly from the riser surface, while remaining spaced from the tool axis;
• and
• a driven member rotatable about a member axis and having a plurality of member walls defining a recess, the tool member receivable therein, the recess characterized as having member walls drivingly engagable with each of the first and second side surfaces of the first and second torque sections of the apex element of the tool member.

A drive assembly for transmission of an externally applied torque, comprising:

• a tool member, comprising:
• a shank element longitudinally rotatable about a tool axis, for receiving an externally applied torque;
• a plurality of tier elements having invariant cross-section along the tool axis, each tier element comprising:
• a first torque section comprising:
• first and second side surfaces extending radially with respect to the tool axis and spaced therefrom, the first and second side surfaces coplanar with the first and second side surfaces of the first torque section of each other tier element;
• a riser surface;
• and
• a step surface;
• and
• a second torque section comprising:
• first and second side surfaces extending radially with respect to the tool axis and spaced therefrom, the first and second side surfaces coplanar with the first and second side surfaces of the second torque section of each other tier element;
• a riser surface;
• and
• a step surface;
• wherein each tier element supports the adjacent tier element more distant from the shank element, and wherein the riser surface of each tier element is nearer to the tool axis than the riser surface of the adjacent tier element nearer the shank element;
• and
• a driven member, rotatable about a member axis and having a plurality of member walls defining a recess, the tool member receivable therein, the recess characterized as having member walls drivingly engagable with each of the first and second side surfaces of the first and second torque sections of a selected tier element.