Basics
b. Buffer the effects of the impacting parts: • Lubricate at the bottom of the sprocket tooth and the gap between the bushing and the roller. • Use specially engineered plastic rollers. (This will also decrease transmission capability. There is virtually no decrease in sound if you change to an engineered plastic sprocket.) If we compare noise from chains and sprockets with other transmission machine parts like belt and pulley or toothed belt and pulley, we find: a. Belt noise is less than the other two. Compared to a flat belt, a toothed belt makes a high frequency noise during high speed. b. Usually, chain transmission is smoother than gear transmission. The chain also differs in that there is no increase in noise level as it wears and elongates during use. 2.3 CHARACTERISTIC PHENOMENA IN CONVEYOR CHAIN Until now, we have primarily been explaining matters that apply specifically to power transmission chains. However, there are some different problems that occur when using conveyor chain. 2.3.1 Coefficient of Friction The tension of transmission chain is calculated by dividing the transmitted power (indicated as kW or horsepower) by the chain speed and multiplying by an adequate coefficient. But in a fixed-speed, horizontal conveyor, tension is decided by those factors shown below: 1. The coefficient of friction between the chain and the rail when conveyed objects are placed on the chain. 2. The coefficient of friction between conveyed objects and the rail when conveyed objects are held on the rail and pushed by the chain. NOTE: There are two types of tension: the first occurs when conveyed objects are moving at a fixed speed, and the second is inertial effects that occur when starting and stopping the machine. We will only talk about the former in this section, and the latter in Basics Section 2.3.2.
Figure 2.22 Tension on a Horizontal Conveyor
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