Code changing mechanism for a mechanical combination lock

A code changing mechanism for a mechanical combination lock, comprising:

• a plurality of function keys and two rows of code number keys provided on a combination lock body, wherein the plurality of function keys comprises a reset key;
• a code changing rack, an intermediate gear, a code changing lock core provided with a code changing keyhole, and each of the code number keys being connected to an individual code changing gear module, wherein each individual code changing gear module comprises:
• a code changing gear and a code controlling chip having two sides;
• a groove for resetting the code is provided on the code changing gear;
• the code controlling chip inserted in the groove to form a code reset site, and a code free site is provided between the code controlling chip and the code changing gear;
• a left straight rack having a left tip opposing a right straight rack having a right tip, are arranged on the code changing rack, and the left straight rack and the right straight rack engage with a corresponding row of code changing gears, respectively;
• wherein the code changing lock core coaxially connects with the intermediate gear, and the intermediate gear engages with two opposing code changing gears thereof.