2. Chain Dynamics
In transmission chain, JIS B 1801-1990 regulates the surface hardness of the pin, the bushing, and the roller (as shown in Table 2.2) to meet the multiple requirements for wear resistance and shock resistance.
Table 2.2. Surface Hardness of Pin, Bushing, and Roller
Component
HV
HRC
Pin
450 or greater 450 or greater 390 or greater
45 or greater 45 or greater 40 or greater
Bushing
Roller
2.2.5 Noise and Vibration When the chain engages the sprockets, it will definitely make noise (Figure 2.21). This is caused by several factors: 1. The chain roller strikes the sprocket tooth bottom. 2. There is space between the roller and the bushing; the roller makes noise by its elastic vibration (in the case of thin rollers, like S-roller). 3. Sprockets vibrate. 4. The fluid held between each part (usually air or lubrication oil) makes shock sounds.
Figure 2.21 Noise Occurs when the Chain Engages the Sprocket
Take for example, an RS80 transmission roller chain and a sprocket with 16 teeth operating at a speed of 123 rpm. (The chain speed is 50 m/min.) In this case, the noise at a point 30 cm from the sprocket will be: with no lubrication, 65 dB (A); with lubrication, 57 dB (A). According to the data given above, the noise made by the chain engaging
the sprocket can be predicted. Please contact the manufacturer. There are some steps you can take to lessen the noise level. a. Decrease striking energy:
• Use a sprocket with many teeth. This reduces the impact velocity while maintaining the same chain speed. • Operate the chain at slower speeds. • Use smaller chain to decrease the chain’s weight.
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