Abstract: A rotary actuator where a thrust bearing ring is positioned at an inside of a tube assembly accommodating oil, thereby reducing abrasion and damage caused by rolling friction and improving rotary power of an axle load by increasing hydraulic pressure of a piston. The rotary actuator includes the tube assembly, a piston, an axle load assembly, and a thrust bearing ring. The tube assembly is provided with a tube spiral portion where a spiral is formed at an inner circumference surface, and is formed of a first passage where oil flows into and out and a second passage spaced apart from the first passage by a fixed distance.

Abstract: A rotary actuator where a thrust bearing ring is positioned at an inside of a tube assembly accommodating oil, thereby reducing abrasion and damage caused by rolling friction and improving rotary power of an axle load by increasing hydraulic pressure of a piston. The rotary actuator includes the tube assembly, a piston, an axle load assembly, and a thrust bearing ring. The tube assembly is provided with a tube spiral portion where a spiral is formed at an inner circumference surface, and is formed of a first passage where oil flows into and out and a second passage spaced apart from the first passage by a fixed distance.

Abstract: A transmission device for farm tractors is disclosed. In the transmission device, a hollow travelling drive shaft and a PTO drive internal shaft are substituted for a typical hollow PTO drive shaft and travelling internal shaft, respectively. The transmission device also has a splined flange for directly transmitting the engine power from the flywheel to the PTO drive internal shaft. In a main change gear unit, a hub sleeve and a main gear shifting shaft are forged into a single structure. A super low-speed change gear unit is connected to a sub-change gear through two sets of shafts capable of allowing the super low-speed change gear unit to be independently operated from the sub-speed change gear unit. The transmission device is thus selectively operated without performing any super low-speed changing action.