The main criticism of hydraulic power transmission systems for water pumps is that power is lost through the hydraulic system. There is obviously a power loss in the hydraulic pump, the hydraulic motor, and the plumbing. However, when evaluating efficiencies against those of other types of power transmission systems, such as gears, belts and pulleys, and direct-connected shafts, it is important to make meaningful comparisons.

Water pump manufacturers typically publish performance curves for their wet-pit pump bowls only, and these curves do not include power losses for any type of power transmission system. This is done because the pump manufacturer does not know the shaft lengths for all possible extended-shaft pumps. Therefore, there is no way the manufacturer can include the losses for the shaft, bushing and bearing supports, couplings, and other transmission parts. Consequently, a user must add to the evaluation the losses resulting from the extended shafting and other transmission parts.

For example, a typical extended-shaft pump may have a column shaft 30 ft (9 m) long. An additional power requirement of 10 to 15% above that of the pump alone would not be unusual for an extended-shaft pump with a gear or belt drive. By comparison, a hydraulically powered pump would typically have a power transmission loss of 20 to 25%—or in other words, would require 10 to 15% more power than an equivalent extended-shaft pump. Thus, a hydraulically powered pump may require, for example, a 30-hp (22-kW) motor rather than a 25-hp (19-kW) motor or diesel prime mover. However, the additional cost of this larger motor should be weighed against the savings in civil works costs and engineering and installation time and the savings resulting from the versatility and automatic operation possible with the hydraulic system.

Survival Treasure

Survival Treasure

This is a collection of 3 guides all about survival. Within this collection you find the following titles: Outdoor Survival Skills, Survival Basics and The Wilderness Survival Guide.

Get My Free Ebook

Post a comment