Fig. 8-4 shows a type of drop hammer such as is used for making drop forgings. The lower die is held on the anvil A and the upper die is held under the hammer B, by keys in the dovetails shown. The dies are not shown in this view. The uprights of the machine form guides between which the hammer is raised and dropped. The hammer is raised by a smooth board which passes between two cylindrical rollers at the top or "head" of the machine. One of these rollers is marked C. Each roller is driven by its own shaft and belt wheel. The two belt wheels are marked WW. The bearings of the roller shafts are arranged so that the rollers may be made to grip the board or may be separated to allow the board to drop between them. This adjustment of the rollers is controlled by the rod D, connected to the foot lever G. The workman may instantly release the pressure of the rollers on the board and cause the hammer to drop, without checking the speed of the rollers themselves. A lever H, shown in front of the machine, is arranged to trip the hammer automatically so that it may not go too high.

The hammer weighs 1000 lbs. or more, and it takes but a few strokes to forge a considerable mass of iron into shape.