A mounting device (100) is provided for connecting two substantially horizontally aligned support beams (20, 30, 40) of a carton flow bed rack (1; 2). The mounting device (100) has a plug (110) pluggable into an end of a first support beam (20) of the support beams. A key (130) is provided as a wedge for fixing the plug (110) in the first support beam (20). An engaging element (120) is arranged at the plug (110). The engaging element (120) is provided to engage a second support beam (30; 40) of the two support beams. The plug (110) is fixable to the first support beam (20) in at least two different plug-positions by means of the key (130).