Idler pulley and Transmission Ratio: In-depth Analysis

idler pulley, also known as the intermediate wheel or bridge wheel, plays an intermediate role in the transmission of motion and power in the gear train. It is not directly connected to the driving wheel or the driven wheel, but indirectly transmits power through meshing with other gears. The uniqueness of the idler is that its addition does not change the size of the transmission ratio, that is, the speed or torque ratio between the driving wheel and the driven wheel remains unchanged. However, the presence of the idler can significantly affect the directionality of the transmission system.

In the field of mechanical transmission, the transmission ratio is a crucial performance indicator, which is directly related to the speed or torque relationship between the driving wheel and the driven wheel.

In short, the transmission ratio is an indicator that measures the ratio of the motion state of the driving wheel and the driven wheel in the gear train. In a fixed-axis gear train, this ratio is mainly determined by two key factors: one is the ratio of the number of teeth of the driving wheel and the driven wheel, and the other is the meshing relationship between them. The tooth ratio, that is, the ratio of the number of teeth of the driving wheel to the number of teeth of the driven wheel, is the basis for calculating the transmission ratio. When the number of teeth on the driving wheel is more than that on the driven wheel, the transmission ratio is greater than 1, which means that for every rotation of the driving wheel, the driven wheel will rotate multiple times. This transmission method is usually used in situations where speed increase is required. On the contrary, if the number of teeth on the driving wheel is less than that on the driven wheel, the transmission ratio is less than 1, and the speed of the driven wheel will be lower than that of the driving wheel, which is suitable for transmission systems that need to reduce speed.

The idler wheel realizes the flexible adjustment of the transmission direction by changing the transmission path of the force. In mechanical systems that need to change the transmission direction, the idler wheel has become an indispensable element. It allows designers to easily achieve the conversion of transmission direction by increasing or decreasing the number and position of the idler wheels without changing the relative positions of the driving wheel and the driven wheel. This flexibility makes the idler wheel widely used in complex mechanical systems, such as automobile transmissions, industrial machinery and equipment, etc.

In addition to changing the transmission direction, the idler wheel also plays an important role in adjusting the wheelbase, dispersing the load, reducing noise and vibration, etc. In terms of wheelbase adjustment, the idler wheel can serve as a bridge to extend the wheelbase, making the transmission system more compact and reasonable. In terms of load dispersion, the addition of an idler wheel can increase the length and complexity of the transmission path, thereby dispersing and reducing the impact and vibration during the transmission process, and improving the stability and reliability of the transmission system.