Mobile driving device for driving a roller conveyor, comprising: - a chassis frame, - a traction device mounted to said chassis frame, wherein said traction device is adapted to move said chassis frame on a supporting surface, - a first drive unit mechanically coupled to said traction device to transmit a driving force to said traction device for moving said chassis frame on said supporting surface, - a roller driving device mounted to said chassis frame, wherein said roller driving device is adapted to be mechanically coupled to one or a plurality of rollers of said roller conveyor, and - a second drive unit mechanically coupled to said roller driving device for transmitting a conveying force to said roller driving device, wherein the traction device comprises a first wheel rotatable about a first axis, a second wheel, rotatable about a second axis, a third wheel rotatable about a third axis and a fourth wheel rotatable about a fourth axis, wherein said first, second, third and fourth axis (21b, 21d, 21a, 21c) are parallel to each other in a straightforward driving condition wherein said mobile driving device moves along a straight line, wherein said first and said second axis (21b, 21d) are arranged at a front end of said chassis frame and said third and said fourth axis (21a, 21c) are arranged at a rear end of said chassis frame, characterized in that in said straightforward driving condition said first axis is arranged in a first offset distance to said second axis, and said third axis is arranged in a second offset distance to said fourth axis, wherein the driving device employed for driving the rollers of a roller conveyor is mobile, such that the driving device can be moved relatively to the roller conveyor and be positioned at different places at the roller conveyor. - a chassis frame, - a traction device mounted to said chassis frame, wherein said traction device is adapted to move said chassis frame on a supporting surface, - a first drive unit mechanically coupled to said traction device to transmit a driving force to said traction device for moving said chassis frame on said supporting surface, - a roller driving device mounted to said chassis frame, wherein said roller driving device is adapted to be mechanically coupled to one or a plurality of rollers of said roller conveyor, and - a second drive unit mechanically coupled to said roller driving device for transmitting a conveying force to said roller driving device, wherein the traction device comprises a first wheel rotatable about a first axis, a second wheel, rotatable about a second axis, a third wheel rotatable about a third axis and a fourth wheel rotatable about a fourth axis, wherein said first, second, third and fourth axis (21b, 21d, 21a, 21c) are parallel to each other in a straightforward driving condition wherein said mobile driving device moves along a straight line, wherein said first and said second axis (21b, 21d) are arranged at a front end of said chassis frame and said third and said fourth axis (21a, 21c) are arranged at a rear end of said chassis frame, characterized in that in said straightforward driving condition said first axis is arranged in a first offset distance to said second axis, and said third axis is arranged in a second offset distance to said fourth axis, wherein the driving device employed for driving the rollers of a roller conveyor is mobile, such that the driving device can be moved relatively to the roller conveyor and be positioned at different places at the roller conveyor.