What is the working principle of the PTO Shaft?

PTO Shaft, or Power Take-Off Shaft, is a device used to drive the working mechanism of supporting agricultural implements, designed to output a portion of the power to achieve this function. PTO is a flexibly installed device located at the front or rear of the tractor, used to transmit engine power to various agricultural tools to enable them to perform field work. The installation position of PTO is flexible, and it can be located at the front or rear of the tractor. Through a universal joint drive shaft, part or all of the engine power can be transmitted in a rotational manner to agricultural tools such as rotary tillers, air suction seeders, power-driven harrows, paddy field agitators, and plant protection equipment, while supporting these machines to perform field work. In terms of power output, PTO has two main working principles: standard speed type and synchronous type.

Standard speed type PTO Shaft

The rotational speed of the standard-speed PTO Shaft remains stable and is not affected by changes in the tractor's gearbox position, as its power is directly transmitted by the engine.Standard-speed PTO Shafts can be divided into non-independent, semi-independent, and independent types. The PTO Shaft shares the main clutch with the tractor transmission system and transmits power through an engagement sleeve, but this design makes frequent operation cumbersome and may lead to engine overload. The semi-independent type transmits power through a secondary clutch in a dual-action clutch, allowing the agricultural implement components to continue rotating when the tractor is stationary, reducing the starting load, but it cannot be precisely controlled during driving. The independent type utilizes a dual clutch to make the power output independent of the tractor's driving state, enabling easy operation of agricultural implements and meeting various operational needs.

Synchronized PTO Shaft

For certain working components of agricultural tools, their rotational speed needs to be adjusted synchronously with the change in tractor speed. For example, the seeding components of a seeder need to discharge seeds at a speed proportional to the tractor speed to ensure uniform seeding. Synchronized power output ensures the normal operation of agricultural machinery such as seeders under specific conditions by synchronizing with the tractor speed, with particular attention paid to the engagement state during reversing. To achieve this, the power of the power output shaft needs to be drawn from the rear of the second shaft of the gearbox and synchronized with the tractor drive wheels. By adding a pair of gears at the power output shaft coupler, synchronous output at different driving speeds can be achieved. However, it should be noted that when reversing, the power output shaft will rotate in reverse, and the working components of the agricultural tool will also rotate accordingly. Therefore, it is necessary to place the coupler in the neutral position before reversing.

It is worth mentioning that some tractors have both of these output modes. In the synchronous output mode, the output shaft only rotates when the tractor is moving, maintaining a constant speed ratio. In contrast, the independent output mode is independent of the tractor's driving state. As long as the engine is ignited and coupled to the output shaft, the output shaft will start rotating, and its speed varies only with the engine speed.

Raydafon PTO Shaft Technical Specifications