Mechanics of the Household / A Course of Study Devoted to Domestic Machinery and Household Mechanical Appliances

by E. S. Keene

THE HYDRAULIC RAM

In places where its use is possible, the hydraulic ram is a most convenient and inexpensive means of mechanical water supply. It is simple in construction, requires very little attention and its cost of operation is only the labor necessary to keep it in repair. Whenever a sufficient supply of water will admit of a fall of a few feet, the hydraulic ram may be used as a pump for forcing the water to a distant elevated point, where it may be utilized for all domestic purposes. The water may be used directly from the ram or stored in an elevated tank as a reserve supply; or accumulated in a pressure tank, where additional pressure is required.

The hydraulic ram has been used since 1796, when it was invented by Joseph de Montgolfier. The principle of its operation is that of the utilization of the energy of flowing water. The running water is made to give up a portion of its momentum to elevate a part of the water, and transport it to a considerable distance. If the source of supply and the fall is sufficient, almost any amount may be elevated and carried to a great distance. Large rams are sometimes used as a means of water supply for small towns. In the use of the double-acting ram, one source of water may be used to operate the ram and water from an entirely different source may be delivered. It sometimes happens that a muddy stream and a clear spring are so located, that the water of the stream can be utilized to furnish the energy for conveying the spring water to a point where it is desired for use. This is accomplished by the double-acting ram in a most efficient manner.

Single-acting Hydraulic Ram.

—Fig. 140 represents the installation of a single-acting hydraulic ram, placed to take water from a spring E, and deliver it to an elevated tank at the house on the hill.

Fig. 140.—Hydraulic ram driven by the water from a spring.

In case the ram must be located at a considerable distance from the spring in order to attain the required fall, a standpipe D—slightly larger than the supply pipe—is used to take advantage of the full force of the water. In long pipes, the friction of the flowing water absorbs a considerable amount of the energy of flow and a standpipe, located as indicated at D, in the picture, will assure the full force of the flowing water in the ram.

The ram is commonly placed in an underground pit as protection from freezing during cold weather, and a drain from the bottom of the pit conducts the waste water away. The supply pipe or drive pipe B and delivery pipe C are buried underground below the frost line as a protection from freezing.

In Fig. 141 a sectional view of the ram shows all of the working parts. The air chamber G is shown partly filled with water; the impetus valve D is that part of the ram which checks the flow of the running water and forces a part of it through the valve E, at the bottom of the air chamber.

Fig. 141.—Cross-section of a single-acting hydraulic ram.

When inactive the valve D stands open and as the water enters from the pipe A, it flows through the valve to the waste pipe but as soon as the full force of the water bears on the valve it will suddenly close. This sudden stop of the flowing water will lift the valve E, and the energy of flow, due to its sudden stopping, will force some of the water into the chamber G. As this action occurs the upward pressure against the valve D is released and it reopens but immediately closes again as the water begins to flow. This process is kept up, each closure of the valve sending a little water into the air chamber. As the water gradually fills the air chamber, it is subjected to the same action as was described in the pressure tank, the air above the surface being compressed and the pressure developed in the space G forces the water out through the delivery pipe where it attains a force that is a factor of the height of the original fall.

The air in the chamber G, is subject to the same conditions of loss as that of the pressure tank, and to be assured of a supply to give pressure to the water, some air must be carried into the chamber with the water. For this purpose the valve F provided. After the chamber is partially filled, there occurs a reaction in the flow of water at each closure of the valve, which causes a little air to be drawn in through the valve F with each impulse. This air bubbles up through the water and enters the chamber where it assures an elastic cushion for closing the valve E.

The flow of water from the supply pipe is regulated at H by a nut on the stem of the impetus valve which permits its regulation. Closing the valve slightly causes a less supply of water to be delivered; opening the valve wider gives a greater supply.

Fig. 142.—Sectional view of a double-acting hydraulic ram.

The Double-acting Hydraulic Ram.

—The diagram of Fig. 142 illustrates the working principle of the double-acting hydraulic ram mentioned above; where the water from a muddy stream is used to drive the ram and that from a separate source, as a spring is delivered.

The construction of the double-acting ram is similar to the single-acting ram, but a separate pipe S discharges spring water directly below the valve which acts just as though it had entered at the drive pipe. The ram in this case is receiving water from the drive pipe D, which operates the valve and furnishes power for elevating the spring water. The spring water enters the ram through the pipe S, to keep the space T filled, directly under the valve. The water which enters the air chamber is, therefore, only that from the spring.

A standpipe is arranged as shown in the figure, with a check valve to prevent the water in the ram from being forced back into the spring water pipe after entering the ram.