Chapter V: Part 5

The width and depth of the pit below the wheel may, for a given wheel, vary somewhat as the water discharged into it is greater or less; therefore, the dimensions should increase with a greater head for the same wheel. The following is an approximate rule for the dimensions of the pit, say for a head of twenty feet: width of pit equal to four times the diameter of wheel, depth below the level of tail-water one and a half times the diameter of wheel. The flume for the wheel should be about three times the diameter of the wheel in its width or diameter, and if it is decked over at the top it should be high enough inside to clear the coupling on the wheel shaft.

_The Watertight Turbine_ is a special machine designed to keep the case tight by the pressure of the water against the gates at the sides, no matter how much these gates wear.

Fig. 125 shows the plan of chutes, gate-seats, gates, and buckets of the wheel. Part of the gates are shown open, and others are closed. The gates make a quarter of a turn in opening, and the same in shutting, and to open all the gates, the gate wheel makes half a revolution. The upper half of case shows the gate-wheel and pinion for operating its parts.

The small illustration is a perspective view of the gate and gate segment used on the watertight turbine. The part cut away forms part of the chute when the gate is open as shown in the lower left-hand side of the figure. The sharp edge of the gate cuts off sticks and rubbish which are liable to get in the wheel, which is an obvious advantage. Another desirable feature claimed for this wheel is the plan of operating the gates in opposite pairs; by this means 2, 4, 6, 8 or 10 full gates may be opened at will, according to the power required.

_Turbines at Niagara Falls._ A number of turbines installed at Niagara Falls, N. Y., are here briefly described; they are about 5,000 horse-power each; a canal leads water from the river to the wheel pit. The water is carried down the pit through steel penstocks to the turbines, which are placed 136 feet below the water level in the canal. After passing through the wheels the waste water is conveyed to the river below by a tunnel 7,000 feet long. The “plan” Fig. 126 shows a cross-section of the wheel pit, with an end view of a penstock, wheel case and shaft. Fig. 126 exhibits part of a vertical section of the wheel pit _and a side view_ of this penstock, with the enclosing case and shaft of the turbine.

This turbine has a rock-surface wheel pit, but this surface is protected by a brick lining having a thickness of about 15 inches. The width of the wheel pit is 20 feet at the top and 16 feet at the bottom, and the cylindrical penstock is 7-1/2 feet in diameter. The shaft of the turbine is a steel tube 38 inches in diameter, built in three sections, and connected by short solid steel shafts 11 inches in diameter, which revolve in bearings. On the top of each shaft is a dynamo for generating the electric power.

In Fig. 126 is shown a vertical section of the lower part of the penstock, shaft, and twin wheels. The water fills the casing around the shaft, passes both upward and downward to the guide passages, through which it enters the two wheels, causes them to revolve, and then drops down to the tail race at the entrance to the tunnel, which carries it away to the river. The gate for regulating the supply is seen upon the outside of these wheels, both at the top and bottom, Fig. 126.

Fig. 128 gives a larger vertical section of the lower wheel with the guides, shaft, and connecting members. The guide passages, and the wheel passages, are triple as shown so that the latter may be filled not only at full gate, but also when it is one-third or two-thirds open, thus avoiding the loss of energy due to sudden enlargement of the flowing stream. The two horizontal partitions in the wheel are also advantageous in strengthening it. The inner radius of the wheel is 31-1/2 inches and the outer radius is 37-1/2 inches, while the depth is about 12 inches. In this figure the gate is represented closed and to open, it moves downward uncovering the guide passages as shown in Fig. 126, the position it occupies loaded.

In Fig. 127 is shown a half-plan of one of the wheels, in a part of which are seen the _guides and vanes_, there being 36 of the former and 32 of the latter. Although the water on leaving the wheel is discharged into the air, the very small annular space between the guides and vanes, together with the decreasing area between the vanes from the entrance to the exit orifices, _ensures that the wheels move like reaction turbines_ for the three positions of the gates correspond to the three horizontal stages or openings through the guides as shown in Fig. 128, _i. e._, three stages of gate.

NOTE.—A test of one of these wheels, made in 1895, developed 5,498
electrical horse-power, generated by an expenditure of 447·2 cubic
feet of water per second under a head of 135·1 feet. The efficiency
of the dynamo being 97 per cent., the efficiency of the wheel and
approaches was 82-1/2 per cent.

The average discharge through one of these twin turbines is about 430 cubic feet per second, and _the theoretic power_ due to this discharge is 6,645 horse-power. Hence if 5,000 horse-power be utilized _the efficiency_ is 75.2 per cent. Under this discharge the mean velocity of water in the penstock is nearly 10 feet per second, but the loss of head due to friction in the penstock will be but a small fraction of a foot. The pressure-head in the wheel case is then practically that due to the actual static head, or closely 141-1/2 feet upon the lower and 130 feet upon the upper wheel.

The absolute velocity of the water when entering the wheel is about 66 feet per second, so that the pressure-head in the guide passages of the upper wheel is nearly 66 feet. The mean absolute velocity of the water when leaving the wheels is about 19 feet per second, so that the loss due to this is only about 4 per cent. of the total head.

NOTE.—The above description refers to the ten turbines in wheel
pit No. 1. The illustrations are those of the wheels called units
1, 2, and 3 which were installed in 1894 and 1895. Units 4 to 10,
inclusive, installed in 1898-1900, are of the same type except that
both the penstock and wheel case have cast-iron ribs on their sides
which rest on massive castings built into the masonry of the side
walls. This arrangement dispenses with the supporting girders shown
in Fig. 126 and gives much greater rigidity to both penstocks and
wheels.

The weight of the dynamo, shaft, and turbine is balanced, when the wheels are in motion, by the upward pressure of the water in the wheel case on a piston placed above the upper wheel. The upper disc containing the guides is, for this purpose, perforated, so that the water pressure can be equalized.

WATER PRESSURE ENGINES.

_Water pressure engines are machines with a cylinder and piston or ram, in principle identical with the corresponding part of a steam engine_; the water is alternately admitted to and discharged from the cylinder, causing a reciprocating action of the piston or ram. It is admitted at a high pressure and after doing its work on the piston is discharged.

The water in some of these machines acquires a high velocity; _the useful work is due to the difference in the pressure of admission and discharge_, whether that pressure is due to the weight of a column of water of more or less considerable height, or is artificially produced.

When an incompressible fluid such as water, is used to actuate piston engines, two special difficulties arise. One is that the lost work in friction is very great, if the water attains a considerable velocity; another is that there is over-straining action on the machinery. The violent straining action due to the more or less sudden arrest of the motion of water in machinery is termed _hydraulic shock_. For these reasons the maximum velocity of flow of water in reciprocating hydraulic machines should generally not exceed 5 to 10 feet per second.

Under high pressure, where there is less object in saving and it is very important to keep the dimensions of the machinery small, Mr. Anderson gives 24 feet per second as the limit of velocity. In large water-pressure engines used for pumping mines the average piston speed does not exceed 1/2 to 2 feet per second.

The suitability of water for _the transmission of power_ has been fully recognized in recent years; the facility with which water under pressure is capable of being utilized, and the advantages that attend its use in motors have resulted in many practical difficulties being overcome, which were at first considered insurmountable.

At the outset of the employment of water pressure it was feared that the water in the pipes and machinery might freeze. This, however, has been found not to be a difficulty where well-known precautions are taken. The working parts should, where possible, be placed under ground, or should be cased in, if they are above ground. _The water should be run out of all valves and cylinders which cannot be cased in_, and protected as soon as the working of the machine ceases.

A very small gas jet or lamp placed near the unprotected parts will prevent freezing.

Experiments have also shown that a mixture of glycerine and water prevents the effects of frost at a temperature as low as 16° Fahr., provided the glycerine has a specific gravity of 1.125, and that it is mixed in the proportion of one part of glycerine by weight to four parts of water.

Where water is used over again in the machines (by returning the exhaust water from the machines to a reservoir), such addition of glycerine is more easily resorted to. Where moderate risks of frost have to be dealt with, the proportion of one gallon of glycerine to 300 gallons of water proves effectual. If the water is at a high pressure, such as 1,500 lbs. to the square inch, it is less liable to freeze than when used at a low pressure.

Again, it was at first feared that accidents might be frequent from the bursting of hydraulic pipes and cylinders under high pressure. Such, however, has been proved not to be the case in practice, and even where pipes or cylinders do burst, the pressure is at once dissipated, as the body of water which can escape at the opening is but slight.

It is desirable to use water which is as free as possible either from suspended matter or from chemical impurity. The former increases the wear and tear of the packing, and is otherwise inconvenient, and the latter acts injuriously on the seats and fittings of valves. Sea-water can be used for hydraulic machinery, but on account of its corrosion, fresh-water is better.

Water-pressure has sometimes been applied to operate machines which are worked continuously and not intermittently, and to continuous working rotary machines. This is unwise, for in applying hydraulic power to the continuous working of shafting or shop tools, the amount of power developed by the hydraulic engine cannot be varied to suit the work to be done, neither can the speed be regulated with sufficient nicety.

HYDRAULIC MOTORS.

_Pressure or Hydraulic Motors_ form an interesting variety of hydraulic devices; they consist of working cylinders with valves and pistons, and resemble forcing pumps in their construction, but differ from them in their operation; the pistons not being moved by any external force applied to them through cranks, levers, etc., but by _the weight or pressure of a column of water acting directly upon or against the pistons_. Pressure engines or motors are applicable to locations—such as afford a suitable supply of water for the motive column; but where-ever refuse, impure, salt or other water can be obtained from a sufficient elevation, such may be used to raise a quantity of fresh water by these machines.

_The stress considered in hydro-mechanics is always a pressure_, as liquids are in general capable of sustaining only a slight tension without disruption: _the intensity of the pressure is measured by the number of units of force per unit of area_. Thus we say, one thousand pounds of pressure per square inch of piston—the pounds and the square inches are the units used in these calculations.

FIGS. 129, 130.

For description see page 151.]

The invention of pressure engines brought to light a _new_ mode of employing water as a motive agent: and also the means of applying it in locations where it could not otherwise be used; with pressure engines the motive agent may be taken to the machine itself. In valleys or lowlands, having no natural fall of water, but where that liquid can be conveyed in tubes from a sufficient elevation (no matter how distant the source may be), such water, by these machines, may be made to propel others; unlike the steam engine, a pressure engine is inexpensive, and simple in construction—it requires neither chimneys, furnaces nor fuel; neither firemen nor engineers, nor is there any danger of explosions. It may be placed in the comer of a room, or be concealed under a counter or a table. It may be set in operation in a moment, by opening a cock, and the instant the work is done, it may be stopped by shutting the same, and thus prevent waste of power.

Pressure engines afford an illustration of the variety of purposes to which a _piston and cylinder_ may be applied. These were probably first used in piston bellows; next in the syringe; subsequently in pumps of every variety; and then in water-pressure and steam engines. _The moving piston is the nucleus or elemental part that gives efficiency to them all_; and the apparatus that surround it in some of them, are but its parts.

The history of machines composed of pistons and cylinders also illustrates the process by which some simple inventions have become applied to purposes, foreign to those for which they were originally designed—each application opening the way for a different one.

In another form hydraulic motors have been adopted, in favorable locations, as first movers of machinery, and when thus used, _they exhibit a very striking resemblance to high pressure steam engines_. Indeed, the elemental features of steam and pressure engines are the same, and the modes of employing the motive agents in both are identical—it is the different properties of the agents that induces a slight variation in the machines—_one being an elastic fluid, the other a non-elastic liquid_.

In steam engines a piston is alternately pushed forward and back in its cylinder by steam; and by means of the rod to which the piston is secured, motion is communicated to a crank and fly-wheel, and through these to the machinery to be driven: it is the same with pressure engines when used to move other machines, except that instead of the elastic vapor of water, a column of that liquid drives the pistons to and fro.

NOTE.—“The hydraulic engine of Huelgoat, in Brittany, is used to
drain a mine; is single-acting, and acts directly to lift the piston
of the pump. It makes five and a half strokes per minute, the stroke
being a little more than eight feet in length. The piston-rod is 767
feet long, and it weighs 16 tons. The power of the engine is derived
from a source at a height 370 feet above its own level.”—KNIGHT.

In default of a natural head of sufficient pressure, the head is sometimes established in _an accumulator_ of power; this is a body of water driven into a reservoir under heavy pressure, by forcing pumps worked by power. In cities where the water distribution is from elevated reservoirs, and in which the water supply is sufficiently abundant to justify the application of a portion of it to industrial uses, the water-engine or motor is recommended.

The following description of a water engine of world-wide adaptation will, if attentively studied, show the working of an approved type of this machine:

Ramsbottom’s hydraulic engine (Figs. 129 and 130), is oscillating, and employs two cylinders _b_, _l_, operating one crank-shaft, _a_, by means of two cranks at right angles to each other. In one of the accompanying figures the channels of induction are marked _j_ and are cast on the cylinders; the dotted circle _c_ shows the position of the supply and discharge pipes; in the other figure these pipes are indicated by arrows. The two views are vertical cross-sections at right angles to each other, one being through the axis of the cylinders and the other through the middle post in which the inner trunnions of the cylinders are journaled. The apertures of induction are seen at _h_ and those of eduction at _i_, and have the form of truncated circular sectors, whose center is the center of motion.

The induction and eduction spaces are divided by a sectoral partition; the apertures of admission and discharge on the sides of the cylinders are of similar construction. The surfaces of contact between the cylinders _b_, _l_ and the support _d_ are planed and polished and are made water-tight by the adjusting screws _m_ _m_ of the pivots. When the piston _p_ is at the end of its course in either direction the cylinder and crank are vertical, and the valves all momentarily closed, the openings by which the channels _j_ _j_ communicate with the discharge and supply pipes presenting themselves exactly opposite the solid sectors which separate _h_ from _i_.

In the next moment the flow of water will recommence, the cylinder discharging itself from the full side of the piston, and filling anew from the opposite side. Air chambers and relief-valves are used as a provision against counter-pressure and hydraulic shocks.

The Brotherhood three-cylinder reciprocating engine is an appliance for producing rotary motion by water-pressure.

The working parts of the Brotherhood three-cylinder hydraulic engine consist only of the three pistons and connecting rods, one crank and one rotating balanced valve and spindle which fits into the driver and is turned direct from the crank-pin; there are no glands, stuffing boxes, or oscillating joints.

It is shown by Figs. 131, 132. The three cylinders, A (made in one casting) are always open at their inner ends, and are attached to a central chamber, B. They contain three pistons, P, which transmit motion to the crank-pin through the rods, C. The water is admitted and exhausted by means of the circular disc valve, V, having a lignum-vitæ seat. The valve is rotated by the eccentric pin, E. A face view of this valve is shown above the steam chest. It has segmental ports which, in rotating, pass over apertures in the valve seat. There being no dead centers, the engine will start from all positions of the crank-pin, and a uniform motion of the shaft is produced without a flywheel.

The pressure is always on the outer end of the piston, so that the rods, C, are in compression, and take up their own wear. This engine is well adapted for transmitting pressure to appliances which are worked intermittently, as, owing to the great speed at which it can be run, it will not only save the loss from friction (where gearing is employed), but will also reduce the friction in the machine itself by enabling the gearing for increasing speed to be dispensed with. The production of this simple hydraulic rotary engine led to its wide application to capstans.

Fig. 133 represents a small hydraulic engine—The Compton Hydraulic Motor—attached to and operating a gas-compressor. It shows a style of water motor in large use in connection with city water-mains. A pressure of 15 to 20 lbs. per square inch is sufficient to operate it; the motor here illustrated occupies a floor space of 9 x 23 inches; it will supply gas burners to the extent of 6,000 candle-power.

The valve motion on the motor is unique in this, the outlets and inlets have a positive motion by which they are simultaneously opened and closed by the motion of the piston; this valve motion is designed to overcome the back pressure; it has a governor, incorporated in the valve-motion for the purpose of maintaining uniform pressure on the main pipes.

HYDRAULIC PACKINGS.

Generally speaking a packing is a contrivance or a material to close a joint. Various greasy materials with gaskets, flax, hemp, etc., are used in joints which are screwed down, also collars of rubber, red lead, luting, graphite, etc.

A most important part in the practical working of nearly all water-pressure machines is the leather collar, the invention of which by Bramah removed the difficulties which had been experienced in making the large ram work water-tight when submitted to great pressure.

It consists of a circular piece of stout leather (see cut page 20), in the center of which a circular hole is cut. This piece of leather is thoroughly soaked in water and is pressed into a metallic mould and so that a section of it represents a reversed ^U^, and is fitted into a groove made in the neck of the cylinder. This collar being concave downwards, then in proportion as the pressure increases, the edge nearest the ram being trimmed down, it fits the more tightly against the ram plunger on one side and the neck of the cylinder on the other. It should be saturated with Neatsfoot or Castor oil so as to be impervious to water.

When the least amount of friction possible is desired in the operating of a hydraulic plunger, there is no form of packing which can surpass a properly prepared and applied Leather “^U^” Packing (Fig. 134), and in practice its position is according to conditions, either in a groove near the upper end of the cylinder, or at the lower end of the ram.

When for any reason it is not desired to use the outer lip of the packing, the resulting form is known as a Cup Packing, (Fig. 135), and when the inner lip is used then we have the Hat or Flange Packing. Fig. 136.

When the water pressure is not over 2,000 lbs. to the square inch, and a greater allowance for friction is not important, a fibrous packing can be used, which is easier of application than these for large sized cylinders.

The loss of power by the best of leather packings is 1 per cent. on 4 in. ram, 1/2 per cent. with 8 in. ram and 1/4 per cent. with 16 in. ram.

HYDRAULIC
APPARATUS

HYDRAULIC APPARATUS.

_Apparatus is another name for machinery_ but it also carries the particular meaning of a complete collection of instruments or devices prepared for a particular use, hence, _hydraulic apparatus_ may be said to include very many combinations of machines to utilize the pressure or weight of water.

A number of these devices are illustrated in the succeeding pages. It were vain to attempt to describe all.

Knight in his Mechanical Dictionary has grouped some six hundred and seventy five terms and names under the heading of “Hydraulic Engineering and Devices.” In the note are given some terms, the definition of which the student may, perhaps, look up; thus: Gyle (the first term given) is a large cistern or vat. The liquor gyle in a brewery is the water-vat or _gyle-tun_.

_Hydraulic apparatus has been developed mainly from two sources._ The “cut and try” method, which of course was the first and second from scientific calculations, based upon both the experiments and upon the mathematics of hydraulics.

It is difficult at this date to say to which procedure the world is the most indebted, but it is plainly discernable that the two methods have been necessary as a check upon each other. Untold thousands of practical experiments and an almost equal number of tables, rules and calculations have been made. The result has been that out of many failures the point of economy and efficiency, aimed at, of hydraulic apparatus is well defined.

NOTE.—_Terms relating to hydraulics named by Edward H. Knight, Civil
and Mechanical Engineer, as above._ Gyle; Sluice Valve; The Sough;
Stade; Worm-safe; Weel; Water-twist; Water-lute; Water-gilding;
Vineficatur; Tun; Tide-lock; Tail-bag; Swash-bank; Sump; Stop-plank;
Sterhydraulic apparatus; Staith; Rip-rap; Quay; Puffer; Psychrometer;
Levee; Leam; Leach; Land tank; Kiddle; Kimelin; Keir; Jetty;
Invert Burette; Hydraulic Blower, etc. Some of these terms go “way
back,” and the above are a specimen only of the 675 headings.

SECTION OF CLAW TYPE HYDRAULIC JACK.]

HYDRAULIC JACK.

_A Lifting-Jack_ is a contrivance for raising great weights by force from below; also called _a jack-screw_. From its derivation from Jack, equivalent to lad or boy, has arisen its modern use as denoting a contrivance which is subject to rough usage. It is operated by _a screw_, whereas—_a hydraulic jack_ is a jack or lifting apparatus operated by some _liquid_, usually oil, acting against a piston or plunger, the pressure on the liquid being produced by a force pump. _The hydraulic jack_ consists of, 1, a cylinder; 2, a ram or plunger; and 3, a pump. One of these machines is shown and described in the Glossary, page 24, another is illustrated by Fig. 138. The Fig. 137 on the opposite page shows the inside view of Fig. 138 but on a different scale. _The names of the parts_ are particularly to be noted.

Movable hydraulic, or screw, jacks serve on numerous occasions most effectively for lifting or propping-up of less accessible parts. Eye-bolts and jack-bolts are arranged for, in all parts that are likely to be handled, to facilitate and accelerate the work in necessarily crowded quarters.

_The base or foot_ is usually made of cast iron or cast steel and may be either round or square to suit requirements. _The cylinder_ is bored from a seamless steel ingot and having a thread upon its lower end is screwed into the base.

_The ram_ is also a tube of seamless steel having a thread at the top and is screwed into the head or cap which is made either of cast iron or cast steel. The lower end of the ram has a thread inside to receive the pump plug which contains the delivery valve, while upon its outside is placed the cup leather packing and the ram packing ring. The pump for operating the ram is from five-eighths to three-quarters of an inch in diameter depending upon the capacity of the jack, and has a plunger packed with a cup leather.

A suction valve is contained within the plunger. A short arm is fitted upon a socket which enters through the side of the head or reservoir. This arm is connected by a pin to the pump inside the ram while the outer end of the socket has a tapered rectangular hole through it to receive the jack-lever. A leather collar packing makes the socket tight where it enters the side of the reservoir.

_To properly use a hydraulic jack._ Place the head under the weight to be raised, be careful to set the jack plumb with a good solid footing; put the lever into the socket with its projection on the bottom side; work the lever until the weight has been raised to the desired height _or an escape of liquid blows out of the safety vent_. Hold the lever up or raise it to its highest position and remove it from the socket to prevent the valve from opening. In lowering insert the lever in the socket with the projection underneath and then cautiously press it slowly down until it brings up against the stop; remove the lever and turn it over with the projection on top; insert the lever in the socket and gently but firmly press it on the end with the right hand clasping the ram with the fore finger, and thumb of the left hand: thus the workman has full control of the jack and can lower and stop as frequently as may be found necessary.

If from any cause the valves stick a few sharp quick strokes of the lever will usually release it and cause it to work, if not, it should be thoroughly cleaned.

Before shipping the brass filling screw should always be screwed down tight, and before using this screw should always be loosened to let the air out and in.

NOTE.—A prominent firm making these tools says: “In our Jacks, rams
are cut and cylinders bored from solid high carbon steel. We have
nearly 300 styles for pushing, pulling or lifting.” This shows the
wide use to which hydraulic jacks are put; the style shown in the
Glossary with its broad base is to be used when the jack stands
upon a light board on the ground and can be placed under the work,
or where steadiness is required. Fig. 139 shows a style to be used
when there is not room enough to get the head of the jack under the
work, and is the style generally used for moving engines, boilers,
machinery, etc.

_In repairing hydraulic jacks_ the following points should be carefully observed; before attempting to repair a hydraulic jack the trouble should be definitely located, next:

Put the jack under a weight and attempt to raise it, carefully watching its action. Should the liquid leak out around the lever socket, the gland should be tightened slightly until this leak disappears. If the packing is worn out unscrew the set screw at the back of the head about one-quarter inch, then withdraw the socket not more than one inch, unscrew the gland and put in a new packing of lamp wick braided and well oiled with mineral oil, which is free from gum. Afterwards put the socket back to its former place and tighten the set screw.

When the pump valve leaks the lever can be worked up and down without raising the ram. This is also true when the plunger packing becomes worn. If the trouble is found with the valve it can be ground by taking out the pump plug and unscrewing the brass bonnet which covers the valve.

Sometimes the jack will become air bound by reason of the accumulation of dirt around the filling plug; this must be removed before the jack will work. Sometimes the liquid will all have been displaced before the ram is half way up, in this emergency the reservoir must be refilled. It often happens that when the workman stops working the lever it will persist in rising to its highest position. This indicates the presence of dirt under the lower or delivery valve. One or two sharp quick strokes of the lever will generally dislodge such obstructions; if this does not bring relief the valve is probably worn so as to need regrinding. _When a jack has been taken apart each part should be thoroughly washed in clean water._

While using, _if the liquid escapes over the top of the cylinder_ the ram packing is too loose, and may be set out by inserting a strip or strips of tin or any sheet metal between the leather and the ram packing ring; all leathers should be kept soft and pliable by saturating with a proper leather dressing such as Frank Miller’s Leather Preservative or Shoemakers’ Dubbing. Castor Oil is excellent as well.

_One man can exert upon the lever_ all the pressure that the jack is capable of raising and this pressure should not exceed 150 lbs. Beyond this the jack will be strained.

_To repack the pump_ remove the pump plug, and unscrew the set screw in the head, then withdraw the socket far enough to permit it to revolve clear of the lug, on the head, which brings the piston head out of the pump.

After the new packing is in place the piston should be worked in and out a few strokes to see if it is right, then replace the plug.

_To fill the reservoir_ remove the filling screw in the top of the head, and fill with a mixture of proof alcohol (95 per cent.), two parts and water three parts for winter use, or for summer use one part alcohol to four parts water.

_When not in use_ the ram in a hydraulic jack should be kept in its lowest position, that is to say, all the way down, _or in_, as the case may be.

IMPORTANT.—Jacks should never be filled with kerosene oil, water or
wood alcohol, for the following reasons: Kerosene oil destroys the
leather packing, water will rust the parts and make them rough, while
wood alcohol attacks the smooth steel surfaces, and thus destroys
both the cylinder and ram. All liquids should be well strained before
putting them into the reservoir and great care should be exercised to
prevent any dirt from getting into this reservoir.

_The Pulling Jack._—The pulling jack, Fig. 139, is used in connection with travelling cranes over wheel presses, quartering machines, planers, drill presses and lathes. Its operation is the reverse of lifting jacks.

This Jack has an improved force-pump on the outside, worked by a lever, which draws the liquid from the upper end and forces it into the space on the opposite side of the piston. The piston rod has one of the rings attached at the end.

By this operation the rings are drawn together and with them the body to be lifted or moved, for it will be understood that this style of jack works either in a horizontal or vertical position. Hooks are furnished instead of rings when desired.

The liquid is introduced into a hole in the side of cylinder, care, being observed to push the piston into the cylinder. The proportions of filling liquid are proof alcohol two parts and water three parts.

To use this jack extend it as far as it can be pulled apart, first opening the valve in the side of force-pump. Now close this valve and work the pump lever.

This jack appeals particularly to the marine engineer, to be attached to the trolley over the engine for the purpose of raising pistons, rods and lifting various parts of the machinery.

_Horizontal Jack._—The accompanying engraving, Fig. 140, shows a horizontal type for pulling armatures on to shafts, putting in cranks pins, and marine work. The directions given for the care and handling of the regular hydraulic jack apply also to this as well as other devices of the same description.

This pump has two plungers of different diameters, the small one inside of the large, so that by throwing a clutch, both plungers may work together as one, or they may be separated, and the smaller one used; as for example, in starting, the larger pump is used as far as possible, _i.e._, until the pressure becomes too great for the large plunger, then the clutch is thrown and the smaller one finishes the work.

The speed of this appliance may be changed to three times greater, and its power reduced to one-third of the maximum by throwing the clutch which brings the large plunger into operation. A rack and pinion with handle is connected with the main ram to cause its return when forced out to its full length. The size shown in Fig. 140 represents a capacity of 200 tons and its approximate weight is 1,200 lbs.

_The Hydraulic Bolt Extractor._—Much harm is done to coupling bolts in driving them out with a hammer or sledge. The hydraulic bolt extractor shown in Fig. 141 is an admirable device to do this work without injuring the bolts or threads. This same apparatus may be used for other purposes as well as that for which it was designed, as will appear from time to time.

_The Hydraulic Punch._—The hydraulic punch has been found of greatest utility in the erection of steel structures, such as buildings, bridges and ship building. It consists of a hydraulic jack attached to a “punching bear” instead of the usual screw to operate the punch. By an ingenious device the punch can be shoved down close upon the work without pumping all the way, as in the earlier styles of hydraulic punches; this means a considerable saving of time and muscle.

The construction and operation of working parts of this punch will be easily understood by referring to the engraving, Fig. 142 where 18 represents the body or “punching bear,” 17 the ram, 19 the raising and lowering pinion to move the ram quickly to its work; 20 shows the die with punch in place above it, secured by its gland; 3 the punch head cistern, the screwed cover having a hole in its center to guide the end 2 of pump plunger 9, having cup leather packing 10, at its lower end; 5 represents the lower socket which carries the arm 4 to operate the piston 6. The suction valve 11 is supported by the spring underneath; 12 is the safety vent; 13 the release or lowering valve operated by the stem 7 which is pushed downward by the projection of the piston 6 whenever the lever is turned and pressed downwards as described in lowering the lifting jacks. The relief valve is kept seated by the spring 14. 8 represents the body of the pump 16 its packing and 15 the ram packing ring. No. 16 does not move, but the ram 17 does, having a cup leather reversed at its upper end applied in the same way and manner as 16, with screwed packing ring. The discharge valve is located behind the pump plunger 9 and is, therefore, invisible.

_A hydraulic punch mounted upon three legs_ or supports is shown in Fig. 143, and it also has a shackle at its back to suspend the punch in mid air as occasion requires.

The details of this punch are like Fig. 142. It has two guards, one each side of the punch to pull the material operated upon off the punch as it is raised by the lower lever. Another very convenient style of hydraulic punch is shown in Fig. 144 where A represents the body of punch, B the operating lever with the lowering or adjusting lever shown broken off. The punch proper is shown at C. The center of gravity of this punch has been so nicely located that by suspending from the handle the ram hangs plumb.

THE HYDRAULIC PRESS.

The hydraulic press consists of

1. A Lever,
2. A Pump,
3. and a Ram working in a
4. Cylinder.

Bramah in the year 1796 brought out a very interesting apparatus which illustrates the law of the equality of pressure which has been widely adopted in the practical use of the hydraulic press. The principle upon which this press works is due to Pascal but it remained for Bramah to put it to practical use. Enormous pressures are developed by operating the hand lever shown at _M_ in Fig. 145, which is connected with pump plunger P. The pump barrel A is very thick and receives its supply from the cistern H through the suction pipe _a_.

Water is delivered from the pump A through a heavy lead pipe into the cylinder _B_ of the hydraulic press. The ram P is made tight by the leather packing _n_ and has a table or platform attached to its upper end as shown. The stationary part _Q_ consists of a heavy cast-iron plate supported by four wrought-iron or machinery steel columns. By operating the handle _M_ of the pump any substances placed between the table on the ram P and the plate Q may be compressed to any reasonable extent.

The pressure which can be obtained by this press depends on the relation of the ram P to that of the plunger P. If the former has a transverse section fifty or a hundred times as large as the latter, the upward pressure on the ram will be fifty or a hundred times that exerted upon the pump plunger. By means of the lever M an additional advantage is obtained.

If the distance from the fulcrum to the point where the power is applied is five times the distance from the fulcrum to the plunger P the pressure on it will be five times the power. Thus, if a man acts on M with a force of sixty pounds, the force transmitted by the plunger P will be 300 pounds, and the force which tends to raise the ram will be 3,000, supposing the section of ram is a hundred times that of the pump plunger.

Over-pressure, is prevented by safety-valve shown in front of the pump A. Fig. 146 shows an enlarged section of the pump used in connection with this press. When the plunger _P_ rises a partial vacuum is formed below it and the suction valve _O_ rises allowing the pump barrel to fill with water through the strainer and suction pipe in the cistern.

When the plunger descends the valve _O_ closes and the water passes through the discharge valve _h_ into the pipe _K_, thence into the cylinder _B_ of the press where it acts upon the ram. When the press has done its work the ram may be lowered by opening the relief valve _r_. The safety valve is shown at _i_. By removing the plug _h_ the discharge valve can be reached to grind it in when necessary.

NOTE.—_Hydraulic Pressure Transmission._ Water under high
pressure—500 to 3000 lbs. per square inch and upwards—affords a very
satisfactory method of transmitting power to a distance, especially
for the movement of heavy loads at small velocities, as by cranes and
elevators. The system consists usually of one or more pumps capable
of developing the required pressure; 2, accumulators, described
on the next page; 3, the distributing pipes, and 4, the presses,
cranes, or other machinery to be operated. This property of fluids
invests us with a power of increasing the intensity of a pressure
exerted by a comparatively small force, without any other limit than
that of the strength of the materials of which the engine itself is
constructed. It also enables us with great facility to transmit the
motion and force of one machine to another, in cases where local
circumstances preclude the possibility of instituting any ordinary
mechanical connection between the two machines. Thus, merely by
means of water-pipes, the force of a machine may be transmitted to
any distance, and over inequalities of ground, or through any other
obstructions.

THE HYDRAULIC ACCUMULATOR.

This useful and indispensable apparatus was designed by Sir William Armstrong. Its use was to secure _a uniform pressure of water in a reservoir by weight_ so that however much or little of this water was used the pressure would remain constant.

ELEVATION.

FIG. 147.]

In the first accumulator which is still in use the ram was attached to the foundation while the cylinder rose and fell as the pressure was utilized. The weights were annular in shape and were hung upon the outside of cylinder. In the modern types of accumulators the cylinder is stationary and the ram supporting the weights is made to rise and fall.

_By means of a hydraulic accumulator a uniform pressure can be established and maintained on all parts of a hydraulic main or system._

PLAN AT BOTTOM.

FIG. 148.]

The volume of water which is used intermittently for the purpose of operating presses—draw-benches for brass and copper tubing and the like is replaced by a pump or pumps which are started and stopped automatically by a connection between the accumulator and the throttle or belt shifter of the pump. The accumulator is used for a double purpose of maintaining a constant pressure and to store up any surplus force of the pumps. The friction loss in the transmission of power by water through mains is very small, as for example: _It has been found that water under a pressure of 700 lbs. per square inch may be transmitted through well proportioned mains, one mile with a loss of only two per cent._

The useful work stored in an accumulator may be calculated by the following rule: _Multiply the area of ram in square inches by the length of the stroke in inches by the pressure m pounds per square inch divided by 33,000 lbs. the equivalent of one H. P._

This represents the work done by one full stroke of the accumulator ram in descending from its highest position to its lowest.

Example. Required the work done by one stroke of a ram twelve inches in diameter, and a stroke of twenty-two feet, under a pressure of 750 lbs. to the square inch. Area of 12 ram = 113·097 square inches. No. of ins. in 22 ft. = 264. Then

113·097 × 264 × 750
------------------- = 678·582 H.P.
33,000

Mr. Tweddel designed the accumulator shown in Figs. 147 and 148 to furnish the varying demand for water where only one appliance of this kind is used in connection with a hydraulic system of shop tools more especially where these tools are numerous.

The ram or spindle _A_ is fixed top and bottom and acts as a guide for the cylinder _B_ which slides up and down upon it.

VERTICAL SECTION.

FIG. 149.]

This cylinder is loaded with weights marked to indicate the pressure which the accumulator will balance with those weights in use. The water is pumped into the bottom through the pipe _C_, and fills the annular space around the spindle. The entire weight of cylinder is raised by the pressure of water acting only on the area of the end of brass sleeve _D D_, which is only 1/2 inch thick all around the center spindle, and extends down through the bottom packing in cylinder, as shown in sectional view. Fig. 149.

A compact arrangement is thus gained and any reasonable, required cubical capacity may be reached by lengthening the stroke.

The accumulator is supplied by two pumps having plungers 1-3/8″ diam. by 3-1/2″ stroke, speed 100 to 120 rev. per minute.

When the loaded cylinder _B_ reaches the top of its stroke, by means of a small chain it closes the suction cock _E_, which shuts off the water supply of the pumps.

To put in a new bottom packing, the cylinder is let down to rest on the wooden blocks _G_, and the spindle is lifted out of its tapered seat at the bottom by a tackle hooked into the eye-bolt at the top. To renew the top leather the bracket holding the top end of spindle _A_, has to be removed.

This accumulator (having only a small area) falls quickly when the water is withdrawn, thus producing a combined blow and squeeze, which is of great advantage in hydraulic riveting.

_The Hydraulic Intensifier_ is a cylinder having two diameters, in principle very like the tandem compound engine. It is used for increasing the pressure of water in hydraulic mains, pipes, or machines, using only the energy of the pressure water to effect the change. But for this distinction a steam pump would be an intensifier. An intensifier worked the reverse way is a “diminisher” as a hydraulic pump usually is, giving a reduced pressure.

_The intensifier is in some respects analogous to the electric transformer._

The intensifier as used in connection with hydraulic apparatus was patented in the year 1869 by Mr. Aschroft, but the principle upon which it works is very much older. Intensifiers are made both single and double acting.

PERCENTAGE OF THE TOTAL AMOUNT OF WATER TAKEN FROM THE RESERVOIR.

| Elevation of discharge above
| delivery valve of ram in feet.
Height +------+------+------+------+------
of fall | 15 | 18 | 21 | 24 | 27
in feet.+------+------+------+------+------
| Percentage.
--------+------+------+------+------+------
2 | ·0724| ·0583| ·0402| ·0307| ·0255
3 | ·1327| ·1020| ·0807| ·0651| ·0532
4 | ·1960| ·1535| ·1234| ·1020| ·0854
5 | ·2614| ·2068| ·1686| ·1404| ·1189
6 | ·3282| ·2614| ·2146| ·1800| ·1535
7 | ·3960| ·3170| ·2614| ·2203| ·1885
8 | ·4647| ·3733| ·3090| ·2614| ·2248
9 | ·5341| ·4303| ·3572| ·3030| ·2614
10 | ·6040| ·4877| ·4058| ·3450| ·2984
11 | ·6745| ·5459| ·4549| ·3874| ·3357
12 | ·7453| ·6040| ·5043| ·4302| ·3733
13 | ·8166| ·6627| ·5540| ·4732| ·4112
14 | ·8881| ·7217| ·6040| ·5166| ·4494
15 | ·9600| ·7809| ·6543| ·5601| ·4877
16 | -- | ·8404| ·7048| ·6040| ·5263
17 | -- | ·9001| ·7555| ·6480| ·5650
18 | -- | ·9600| ·8064| ·6921| ·6040
19 | -- | -- | ·8574| ·7364| ·6430
20 | -- | -- | ·9086| ·7800| ·6823
21 | -- | -- | ·9600| ·8254| ·7217
22 | -- | -- | -- | ·8701| ·7612
23 | -- | -- | -- | ·9150| ·8007
24 | -- | -- | -- | ·9600| ·8404
--------+------+------+------+------+------
| Elevation of discharge above
| delivery valve of ram in feet.
Height +------+------+------+------+------
of fall | 30 | 35 | 40 | 45 | 50
in feet.+------+------+------+------+------
| Percentage.
--------+------+------+------+------+------
2 | ·0181| ·0112| ·0063| ·0027| --
3 | ·0441| ·0326| ·0243| ·0181| ·0132
4 | ·0724| ·0560| ·0441| ·0348| ·0281
5 | ·1020| ·0807| ·0652| ·0533| ·0441
6 | ·1327| ·1063| ·0870| ·0724| ·0608
7 | ·1640| ·1327| ·1096| ·0920| ·0782
8 | ·1960| ·1595| ·1327| ·1121| ·0960
9 | ·2285| ·1868| ·1561| ·1327| ·1142
10 | ·2614| ·2145| ·1800| ·1535| ·1327
11 | ·2947| ·2425| ·2041| ·1746| ·1514
12 | ·3282| ·2708| ·2285| ·1960| ·1704
13 | ·3620| ·2994| ·2532| ·2177| ·1896
14 | ·3960| ·3282| ·2780| ·2395| ·2090
15 | ·4303| ·3572| ·3030| ·2614| ·2285
16 | ·4647| ·3863| ·3282| ·2835| ·2482
17 | ·4993| ·4157| ·3535| ·3058| ·2680
18 | ·5341| ·4451| ·3790| ·3232| ·2380
19 | ·5690| ·4746| ·4046| ·3507| ·3081
20 | ·6040| ·5042| ·4303| ·3733| ·3282
21 | ·6392| ·5340| ·4561| ·3960| ·3486
22 | ·6745| ·5640| ·4820| ·4188| ·3688
23 | ·7098| ·5940| ·5080| ·4417| ·3892
24 | ·7433| ·6241| ·5341| ·4657| ·4097
--------+------+------+------+------+------
| Elevation of discharge above
| delivery valve of ram in feet.
Height +------+------+------+------+------
of fall | 60 | 70 | 80 | 90 | 100
in feet.+------+------+------+------+------
| Percentage.
--------+------+------+------+------+------
2 | -- | -- | -- | -- | --
3 | ·0063| ·0017| -- | -- | --
4 | ·0180| ·0112| ·0063| ·0027| --
5 | ·0307| ·0217| ·0150| ·0099| ·0063
6 | ·0441| ·0325| ·0243| ·0180| ·0132
7 | ·0580| ·0441| ·0340| ·0264| ·0205
8 | ·0724| ·0560| ·0441| ·0351| ·0281
9 | ·0870| ·0682| ·0545| ·0441| ·0360
10 | ·1020| ·0807| ·0651| ·0533| ·0441
11 | ·1172| ·0934| ·0760| ·0627| ·0524
12 | ·1327| ·1063| ·0870| ·0723| ·0608
13 | ·1483| ·1194| ·0983| ·0821| ·0694
14 | ·1640| ·1327| ·1096| ·0920| ·0782
15 | ·1800| ·1460| ·1211| ·1020| ·0870
16 | ·1960| ·1595| ·1327| ·1121| ·0960
17 | ·2123| ·1731| ·1444| ·1223| ·1050
18 | ·2286| ·1868| ·1561| ·1327| ·1142
19 | ·2449| ·2006| ·1680| ·1430| ·1262
20 | ·2614| ·2145| ·1800| ·1535| ·1327
21 | ·2780| ·2286| ·1920| ·1640| ·1420
22 | ·2947| ·2425| ·2041| ·1746| ·1514
23 | ·3114| ·2567| ·2163| ·1853| ·1609
24 | ·3282| ·2708| ·2185| ·1960| ·1704

_For explanation of these tables see page 177._

HYDRAULIC RAM.

_A hydraulic ram or water-ram is a substitute for a pump_ for raising water by means of the energy of the moving water, of which a portion is to be raised. It was considered a notable discovery when it was demonstrated by Daniel Bernovilli, in the beginning of the 18th century, _that water flowing through a pipe, and arriving at a part in which the pipe is suddenly contracted, would have its velocity at first very greatly increased_.

The hydraulic ram owes its efficacy to the fact that when a flow of water in a pipe is suddenly stopped, a considerable force is generated by the momentum of the water, by its change from a state of motion to a state of rest. In practice, the pipe conveying water from the reservoir or head, connects with a chamber which has a valve opening downward, or outlet valve, allowing the current of water to pass on or escape when the valve is open; but on flowing the current in the pipe acquires sufficient force to close this valve, which checks the flow in the pipe.