A conveyor, comprising; two opposite rolls (1, 2), a frame that comprises two opposite beams (3, 4) that carry the rolls (1, 2) and extend in their longitudinal direction between the rolls (1, 2), an endless metal belt (5) extending in a path around and carried by the two rolls (1, 2), and a support element (11) that extends between and is connected to each of the two beams (3, 4), wherein at least one of the rolls (1, 2) is displaceable in the longitudinal direction of the beams (3, 4) in order to enable tightening or loosing of the belt (5), and wherein there is provided a jack (10) that is connected to and acts on said roll (1) for said displacement thereof. The jack (10) is displaceable between at least two operative positions in the longitudinal direction of the beams (3, 4).