Rope Pump Models


The rope pump is a simple technology that has been widely applied in the Nicaraguan rural area, especially in water and sanitation projects. But it has also become an alternative to support small farm production through other models that constitute the diversification illustrated for future producers or persons interested in this technology.

The following models exist:

THE DOUBLE-CRANK PUMP

The double-crank pump is similar to the extra-strong pump, with certain adaptations in order to be able to extract water from relatively deep (37 to 50 meters), dug or drilled wells. When two people work to turn the wheel, the power applied is duplicated (75 watts x 2) and therefore, there is a capacity to raise the water column from this depth. This is the reason for the double crank on this type of pump.

The structure of this pump is the same as the extra-strong pump. The pieces of tire that are used to make the wheel are from a # 16" hubcap, which are more flexible. This is why they have 12 clambs made of iron strips of 1/8" x 1" with their respective spokes and supports. It is important to mention that even though this pump is being installed on a dug well, it should be installed as if it were a drilled well in order to increase contact between the wheel and rope and avoid sliding.

The two handles are attached together by soldering down the center of the two bushings of the wheel, so that it does not suffer added weight since tension is placed on the bushings. The bearings are wooden blocks with an inside nominal diameter of 3/4", and therefore the handles and wheel are removable. The piston and pumping pipes have nominal measurements of 1/2", and the discharge pipe is 1". The rope to be used is a relatively thick nominal measurement of 1/4", so as to ensure that it has sufficient strength to support the weight of the water column. Furthermore, when the rope takes up more of the space in the pipe, the volume of water to be extracted is less, thus making the crank easier to turn and the human energy expended less. On the other hand, at this depth knots are not used to fasten the pistons. Instead braids or injected polyethylene knots are used.

In these pumps which are installed for depths of less than 37 meters, pipes with larger diameters and 20" hubcaps can be used, resulting in greater amounts of water for special applications such as draining wells.


THE PUMP FOR DRILLED WELLS

The double-crank pump, which has a proven limit of 50 meters in depth, is recommended for drilled wells, as they are usually deep. Drilled wells originated in water and sewage projects in rural areas, and their diameter is in the range of 4" to 12". When the well is drilled, a PVC pipe is inserted becoming the walls of the well. A PVC plug is placed on the terminal of the pipe. Installing a rope pump on a drilled well is simple, but certain technical parameters must be considered. A 32" (long) x 23.5" (wide) x 14" (high) pedestal must be built so that the exit pipe is located at the height of a bucket.

An enamel ceramic piece with fastening support is installed in the pump structure, which must be aligned with the return pipe so as to ensure that the rope enters vertically without touching the pipe. Another method for inserting the rope into the pipe is by using a curved pipe which starts in a horizontal direction below the wheel and almost makes a 90o turn to enter the return pipe which projects from the plug of the casing. This curved pipe can be made of PVC, filled with sand and heated slowly. However, the rope tends to wear a groove in the curved pipe made of PVC. A good alternative to replace the PVC curved pipe is bent thin-walled galvanized pipe.

Since these wells are deep and of a small diameter, on installation the guide tends to twist and get tangles up with the rope. This is the reason for double pipes, the pumping pipe and the return pipe, which lead to the sealed plug which has two holes, and which should be aligned with the ceramic piece. The installation accessories should be placed past the sealed PVC plug and should remain firm so as to ensure that the pipes do not sink to the bottom.
The guides used are cylinder-shaped and must measure 1" less than the diameter of the well. The ceramic piece for 4" wells is smaller than that normally used on drilled wells.


OTHER TYPES OF PUMPS

The other types of pumps previously mentioned, such as the aerial pump (to fill tanks), the Bici-bomba (bicycle type pump), the Air-pump (activated by the wind), the animal traction pump (activated by a horse or ox), the motor pump (activated by a gasoline motor) and the Tractor adapted pump (Activated by the force of a tractor), are not discussed in this document.