YTH externally mounted reduction cylinder with the introduction of Germany advanced production technology of electric drum, a variety of fixed belt conveyors, bucket elevators, winches and other supporting a new drive. Its internal use of hardened planetary gear mechanism, the motor and the drum exposed directly connected, with a large carrying capacity, strong overload capacity, smooth transmission, low noise, long life, easy maintenance, safe and reliable operation. Can meet a variety backstop, plastic packets and other requirements. Explosion exterior electric drum across its flag dI, dIIAT4, dIIBT4. dI suitable for methane or coal dust in mines, dIIAT4 suited to have I, IIA stage T2-T4 group explosive mixtures dangerous places, dIIBT4 suited to have I, IIA, IIB stage T2-T4 group explosive hazardous mixtures place. By JB / T7330-94 standard, equipped with explosion-proof motor, code-named B, with backstop codenamed N.