Belting, horsepower transmitted

Narrow belts, because of their relatively higher horsepower capacity, usually provide substantial space and weight savings compared to classical belts. For instance, narrow belts can transmit the same horsepower loads in M to % the space of a classical belt drive. Narrow belts often allow the use of greater speed ratio between driver and driven machine. 

The difference between the brake horsepower and the water or liquid horsepower is the pump efficiency. The requirement in either case is the horsepower input to the shaft of the pump. For that reason, the brake horsepower represents the power required by the pump, which must be transmitted from the driver through the drive shaft through any coupling, gear-box, and/or belt drive mechanism to ultimately reach the driven shaft of the pump. Therefore, the losses in transmission from the driver to the pump itself must be added to the input requirement of the driven pump and are not included in the pump s brake horsepower requirement. 

This is the horsepower consumed by the cylinders and does not contain any losses in transmitting the power from the driver to the point of use, such as belts or gears. It does contain 95% mechanical efficiency for the cylinder itself. 

Wide range variable-speed drives can easily allow for overall speed variations of up to 10 1 and transmit up to 100 horsepower (75 kW). Generally the higher the horsepower load, the lower the speed ratio. Variable-speed belts have a wide, thin cross section in comparison to other V belts (Fig. 5.76). 

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