Transmission belt is quite important in power transmission systems. It can generate much power during the working process. At the same time, it may also loss energy. Now let us see something about the power transmission belts.
Power transmission efficiency and parasitic idling losses in belt machine elements have been considered for over 50 years. Efficiency, slip, and temperature characterize the performance of large agricultural belts employed in the demanding propulsion and grain separation applications of high capacity combines. Both cogged and wrapped belts exhibit efficiencies above 90 per cent, although cogged belt generally display higher efficiency, lower slip, and cooler temperatures. Cogged efficiencies are above 94 percent throughout the application power range.
Idling power losses depend on tension, diameter, speed, and width, etc. The tension effect results from frictional sliding as a belt enters and exits a pulley; whereas, the diameter dependence is a consequence of bending hysteresis as a belt flexes from straight span to curved pulley paths. Since pulley speed controls the rate of frictional and hysteretic energy dissipation, it is essentially proportional to power loss. The influence of belt width is due to both increased frictional and bending losses resulting from multiple industrial belts, larger industrial V-belt cross sections, and wider V-ribbed and synchronous belts.
And the bending hysteresis is the principal factor determining power loss comparisons between cross sections. Consequently, due to increased flexibility over plain base belts industrial V-belt cogged constructions require the least energy and run at lower temperatures under no load. Industrial Vee and Vribbed belts are approximately 75 percent accounted for by the idling losses; while idling loss accounts for about 50 percent of the synchronous belt transmission losses.
The cogged belts demonstrated lower slip level further augments its efficiency and temperature performance. Industrial Vee and V-ribbed belts, sizes and constructions are compared for varying diameters with V-ribbed and cogged advantages being greatest at smaller diameters. The accessory belts temperature performance is presented as a function of slip and torque levels. Cogged efficiencies are above 94 percent throughout the application power range.
According to the above content, the major portion of belt energy loss during power transmission is attributed to parasitic bending hysteresis and sliding friction. The cogged construction which minimizes the hysteretic component of parasitic loss yields the greatest efficiency in each industrial test. Although there are many disadvantages about the transmission belt, it still plays a rather important role in the power transmission.
