Type Ommi 51 Dump Cars Between 1951 and 1970 the DB purchased a total of 3,905 dump cars which had already turned in excellent results on the Westphalian Provincial Railroad (WLE). They were designated as the type Ommi 51. This designation had the following meanings O = an open car that can be tipped or that has self-unloading equipment, mm = a load limite of more than 21 metric tons, i = dump hoppers, and 51 = type number (new cars were given type numbers in the range of 50 to 99 from 1951 on). The type Ommi 51 had five hoppers that could be tipped on both sides, thus allowing the freight load to be unloaded directly into road vehicles (such as trucks), over bunker walls, etc. The hoppers were fabricated of steel, welded together, and reinforced with hollow supports. The car's underbody was a latticework design with rolled steel shapes und supported the vertical roller guides, on which the hoppers, with their cradles equipped with guide pins, roll for dumping. The hoppers could be unloaded partially or completely. The hopper was locked in place in the selected dumping position. After the return lock was released the emptied hopper rolled back to its normal position and the hopper restraint locked into place. The roll process for dumping was very well thought out in kinematic terms and, in conjunction with the admittedly less advantageous high center of gravity for the hoppers, allowed direct transfer of the load into trucks without any aids. The simplicity and quickness of the process could hardly be improved on in principle. Since the cars were inclined to tip over during the unloading process, they had to be safeguarded in advance with special track clamps. Despite all of this these dump cars were very much in demand, mostly for the transport of specifically heavy bulk freight such as sand, gravel, ballast, and stones.