The invention relates to a control and regulation device for safeguarding a conveyor device (1), in particular, a crane unit in the case of overload. A brake device (11, 18) acting on the conveyor device (1) is provided, along with a controller (30) for the brake device (11, 18), an overload sensor (29), recording the overload and emitting an overload signal and a speed sensor (31, 24), recording a cA process for the production of iohexol comprises alkylating 5-Acetamido-N,N'-bis(2,3-dihydroxypropyl)-2,4,6- triiodoisophthalamide using 2(2-methoxy-ethoxy)-ethanol as solvent in the presence of a base, and optionally isolating crude iohexol from the reaction mixture. Preferably, the alkylating agent is 1-chloro-2,3 propanediol and the base is an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide.onveyed item speed and emitting a speed signal. The controller (30) reacts to the overload signal on the braking device (11, 18), such that this device stops the conveyor device and thus safeguards a conveyed item (16).; On a subsequent unload signal the controller (30) releases the conveyor device (1) such that the conveyor device (1) is moved into an unload position by the effect of the load of the conveyed item (16) and the effect of the braking device (11, 18) on the conveyor device (1) is regulated according to the speed signal from the speed sensor (24, 31) such that the conveyed item (16) is moved into the unload state at an essentially constant conveyor speed. The invention further relates to a conveyor device with such a control and regulation arrangement and a container crane unit with two conveyor devices provided with such a control and regulation device.