JHM\ZLYJ\ZSYJ Series gearbox is a drive device with high-precision and hard tooth surface and thrust bearing designed to match with screw extruders. It is designed according to standard ZBJ19009-88. The main parts are made of high strength alloy steel. The gears are manufactured by way of carburizing quenching hardening, and gear grinding. Its precision is up to Grade 6 (GB10095-88). Thrust bearing with over-specification is mounted on the front end of hollow output shaft to accommodate screw back pressure forces. The whole unit is small volume, high carry capacity, stable drive, low noise and high efficiency.