Can seamer

In a can seamer, after a control mode of a drive motor has been switched to a type-changing mode, if an action button is depressed, in response to signals issued from a rotational position sensor, the drive motor moves can seaming mechanisms one pitch by one pitch via a center shaft and stops at predetermined positions. At the stopped position, an actuator is operated to depress the top end of a seaming roll shaft. By this operation, a gap clearance is formed between a rotary frame and a seaming lever. Then seaming rolls are dismounted and replaced. The seaming lever connected with a seaming chuck via a bracket is removed, and thereby a type-changing work can be carried out. In addition, in the type-changing work of the can seamer, the vertical positional adjustment in a fitting between a seaming lever and seaming rolls is easily carried out. Furthermore, the knock-out pad can be replaced in a one-touch operation.