Gear lock

A gear locking element, for use with a movable toothed gear having a gear tooth with first and second gear sides, the gear sides movable in first and second directions, comprising:

• a body movable between a free movement position and a gear locked position;
• the body having guide surface means for engaging a tip portion of the first gear tooth and guiding the gear towards a proper position during an initial movement of the body from the free movement position to the gear locked position;
• the body having indexing surface means for engaging a second gear tooth and guiding the gear in the second direction towards the proper positions;
• the body having first and second locking faces positioned opposite the first and second gear sides when the gear is in the proper position and the body is in the gear locked position, the gear sides and locking faces defining first and second contact planes when in contact;
• the first and second contact planes being oriented at first and second angles to the first and second directions;
• the first and second gear sides exhibiting first and second coefficients of friction with the first and second locking faces;
• and
• the tangents of the first and second angles being less than the first and second coefficients of friction so that movement of the gear in either of the first and second directions is substantially prevented by the engagement of the first and second locking faces with the first and second gear sides.

A method for locking a movable gear, including gear teeth having first and second sides, into a chosen position, the gear movable in first and second directions, comprising the following steps:

• selecting a locking element having first and second faces, the faces facing generally opposite direction;
• engaging a tip portion of a gear tooth, having at least one of the first and second sides, during an initial movement of the locking element towards a locking position so to initially guide the gear towards the chosen position;
• moving the locking element to the locking position with the first and second faces opposite the first and second sides;
• the selecting step carried out by configuring the faces so the first and second faces contact the first and second sides at first and second respective contact positions, the faces and sides at the contact positions defining first and second contact planes oriented at first and second chosen angles to the first and second directions;
• and
• limiting the first and second chosen angels to angles with tangents less than the coefficients of friction between the sides and the faces so to lock the gear against substantial movement.

A method for locking a movable gear, including a gear tooth having a side, into a chosen position, the side movable in a direction, comprising the following steps:

• selecting a locking element having a face;
• engaging a tip portion of a gear tooth, having at least one of the first and second sides, during an initial movement of the locking element towards a locking position so to initially guide the gear towards the chosen position;
• engaging a gear tooth, other than a gear tooth having at least one of said first and second sides, by the locking element after the tip portion engaging step to continue guiding the gear towards the chosen position;
• moving the locking element to the locking position with the face opposite the side;
• the selecting step carried out by configuring the face so the face contacts the side at a contact position, the face and side at the contact position defining a contact plane oriented at a chosen angle to the direction;
• and
• ensuring the coefficient of friction between the side and the face is greater than the tangent of the chosen angle so to lock the gear against substantial movement in the direction.

A method for locking a movable gear, including a gear tooth having a side, into a chosen position, the side movable in a direction, comprising the following steps:

• selecting a locking element having a face;
• engaging a tip portion of a gear tooth, having at least one of the first and second sides, during an initial movement of the locking element towards a locking position so to initially guide the gear towards the chosen position;
• engaging a gear tooth, other than a gear tooth having at least one of said first and second sides, by the locking element after the tip portion engaging step to continue guiding the gear towards the chosen position;
• moving the locking element to the locking position with the face opposite the side;
• the selecting step carried out by configuring the face so the face contacts the side at a contact position, the face and side at the contact position defining a contact plane oriented at a chosen angle to the direction;
• and
• limiting the chosen angle to an angle with a tangent less than the coefficient of friction between the side and the face so to lock the gear against substantial movement in the direction.