MICROFICHE REFERENCE LIBFUUW - Cd3wd.com

30raising the bucket through greater distances, the discharge again decreases.However, by employing one of several additional devices, the discharge, aswell as the lift, of the rope and bucket* can be increased.3.2.1.3. Bucket, Rope, and RollerPulling the rope over a single roller or pulley theoreticallyrequires the lifter to exert the same amount of energy as lifting withoutthe pulley, plus a small amount of overcome friction. However, centeringthe bucket over the well or water source prevents dragging it up the wellwall (with subsequent splashing and friction) and allows the lifter topull hand over hand without bending or reaching. Also, the lifter caneither utilize gravity by pulling the rope down with his weight, or walkaway from the pulley with the rope. By using a greater number of pulleysin various arrangements, the amounts of force that must be exerted by thelifter can be significantly decreased, but of course, the distance to pullis increased. This way, the capacity (i.e., weight) of the bucket canbe increased.Of course, with the introduction of such mechanical devices as thepulley, friction losses become a reality and will be reflected as thedifference between the measured pull and that predicted by theory. Anadditional initial cost for pulleys, supports, etc., has also been introduced,as well as a maintenance requirement, e.g., lubricating the pulley.Costs of rope and pulleys will vary greatly, depending on quality, size,and geographical availability. Although commercially manufactured blockand tackle units and pulleys can be purchased to decrease wear and friction,*This combination will be used throughout further discussion, althoughother combinations with bags, chains, etc., can often be substituted.