Transmission device for knife changing mechanism of a machine center

A transmission device for knife changing mechanism of a machine center, comprising:

• a motor connected to a top of a casing and driving an output shaft, a first bevel gear connected to said output shaft;
• a cam disk mounted to a cam shaft in said casing and a second bevel gear mounted to said cam shaft and engaged with said first bevel gear, a first groove defined in a first side of said cam disk and a second groove defined in a second side of said cam disk;
• a rack having a first pin extending therefrom and movably engaged with said first groove, an arm having a first end thereof pivotally connected to said casing and a second pin extending from said arm and movably engaged with said second groove;
• a main shaft movably extending through said top of said casing and having a toothed section and an annular groove defined in an outer periphery of said main shaft, a second end of said arm engaged with said annular groove, a tube connected to said top of said casing and said main shaft movably inserted in said tube, a first detection device and a second detection device respectively and radially connected to said tube, and
• a control shaft extending through an aperture defined through said top of said casing and fixedly connected to a cap on said top of said casing, a first idle gear and a second idle gear respectively mounted to said control shaft, said first idle gear engaged with said rack and said second idle gear engaged with said toothed section on said main shaft.