A device for clamping a blade of shears for traverse cutting of strips includes a clamping bar for the clamping the blade, and a device for displacing the clamping bar in its release position, with the device having a first piston having a piston rod connected at its end remote from the piston with the clamping bar, and a second piston spaced from the first piston and having a piston rod section acting on the first piston, a first connection-bore connects the space in the front of the first piston with the space in the front of the second piston, and a second connection bores connects the space behind the second piston with the space behind the first piston, wherein the first and second connection bores are formed in the rod section of the second piston.