(1) The chain speed and the driven sprocket angular speed change periodically, resulting in an additional dynamic load. The greater the acceleration of the chain, the greater the dynamic load. The acceleration of the chain is
It can be seen that the higher the speed of the sprocket, the larger the chain pitch and the fewer the number of sprocket teeth, the dynamic load will increase.
(2) The speed of the chain along the vertical direction also changes periodically, so that the chain produces lateral vibration, which is also one of the reasons for the dynamic load of the chain drive.
(3) When the chain link enters the sprocket, the chain link and the sprocket gear engage at a certain relative speed, and the chain and the gear teeth will be impacted and produce additional dynamic load. As shown in Figure 6.11, according to the principle of relative motion, the sprocket is regarded as static, and the chain link enters the gear teeth at the angular velocity -w and produces an impact. This phenomenon is intensified with the increase of sprocket speed and chain pitch. The transmission produces vibration and noise.
(4) If the chain tension is not good, the chain slack, in the case of starting, braking, reversing, load changes, etc., will produce inertial impact, so that the chain drive produces a large dynamic load.
Because of the dynamic load effect of chain drive, chain drive is not suitable for high speed.