WeChat：chinafreezer

23/11/2012

 

Properly designed belt transmission systems are highly efficient and quiet. However, they require periodic maintenance to ensure efficient operation. In addition, certain types of belts are more efficient than others.

 

V-belts are used in the majority of belt drives. These belts have a trapezoidal cross section that wedges into pulleys to increase friction and power transfer capability. In operation, V-belt efficiency can deteriorate by as much as five percent over time if the belt is not periodically re-tensioned, as under-tensioned belts lead to slippage and reduced power transfer efficiency.

 

Cogged belts have slots that run perpendicular to the belt length. These slots reduce belt bending resistance and allow the belts to be used with V-belt pulleys. Cogged belts run cooler, last longer and are about two percent more efficient than standard V-belts. Therefore, cogged belts should be considered as replacements for V-belts wherever possible.

 

Synchronous belts have teeth and require the installation of mating toothed drive sprockets. These belts are about 98 percent efficient and maintain that efficiency over a wide load range. Synchronous belts require less maintenance and retensioning, operate in wet and oily environments, and run slip-free.

 

However, while synchronous belts are extremely efficient, cogged belts may be a better choice when vibration damping is needed or shock loads cause abrupt torque changes that could shear a synchronous belt's teeth. Synchronous belts also make a whirring noise that might be objectionable in some applications.

 

Additionally, proper belt alignment and tensioning are critical to ensure efficient operation. Improper tensioning leads to inefficient power transmission, belt failure and associated costs. If a belt is not running at optimum tension, it is wasting energy and money. Manufacturers offer a variety of tools that help ensure the proper installation of belt drives, including alignment tools and tension guides.

 

Another maintenance concern and efficiency loss is sheave wear. Misalignment and improper belt tensioning can cause excessive wear on sheaves. When sheaves wear, a formerly flat groove sidewall takes on a concave shape and the surface that interacts with the belt is compromised. Eroded sheave sidewalls can cause up to 12 percent loss in V-belt drive efficiency; and rough, worn sidewalls can reduce belt life by up to 50 percent. Belt manufacturers offer sheave gauges to help assess the condition of the sheave wall and make good decisions regarding replacement.