Victoria and Albert Museum.

Catalogue of the mechanical engineering collection in the science division of the Victoria and Albert museum, South Kensington online

. (page 42 of 71)
Online LibraryVictoria and Albert MuseumCatalogue of the mechanical engineering collection in the science division of the Victoria and Albert museum, South Kensington → online text (page 42 of 71)
Font size
QR-code for this ebook

is circulated through it, about half the loss of work through
heating being thereby avoided ; clearance spaces must be reduced
to a minimum and the only limit of speed is that at which the
valves will operate satisfactorily. For compressing air to very
high pressures it is now usual to work in stages, the pumps, of
diminishing diameters, being usually on one long piston-rod, the
air compressed in the first pump passing through external
cooling pipes or " intercoolers " before being further compressed
in the second pump, and so on; in this way the loss of power
through the thermal changes during' compression can be greatly
reduced, and several mechanical difficulties are avoided.

Rotary Pumps. These, although acting by force and suc-
tion, differ from the preceding class in the use of a rotating or
oscillating " piston " to effect the enlarging and contracting of
the pump chamber. Ramelli in 1588 describes one with an
eccentric chamber and rotating blade (cf. No. 667), and also
one in the form of two spur-wheels geared together in a closely-
fitting casing (cf. No. 668). Rotary mechanism has been much
more successful when applied to pumps than to motors, especially
when restricted to moderate heads where the leakage due to
the packing is small. The low speed of rotation that may be
adopted is also an advantage.

Centrifugal Pumps. These differ from the preceding classes
in that the energy is used in giving momentum to the water
instead of acting by positive pressure. In 1682 Denis Papin
schemed the Hessian pump which had a wheel or impeller with
four straight radial blades arranged in a circular casing. Several
arrangements of Barker's mill reversed were proposed during
the succeeding century, but nothing better appeared till 1818,
when the Massachusetts pump was introduced ; from this the
rise of the present centrifugal pump may be said to date ; this
differed from Papin's mainly in being immersed in the water to
be lifted, and in having an eccentric casing; it is thus less
inefficient than the circular casing in converting the kinetic
energy, that has been imparted to the water on leaving the
impeller, into pressure energy. In 1839 Andrews brought out
the efficient spiral or volute casing. In 1849 J. G. Appold
determined by experiment the most efficient curve for the blades
of the wheel (see No. 669). About 1850 Prof. J. Thomson first
suggested the whirlpool chamber a space surrounding the wheel
in which a free vortex could be formed.

For high lifts the peripheral speed of the wheel must be
high and the skin friction becomes serious. Gwynne and others
early tried to obviate this by employing two or more pumps in
series, the several wheels being on the same shaft, but the


efficiency proved low. Recently Sulzer and others have suc-
ceeded in obtaining efficiently any desired lift. A further
advance in efficiency has been obtained by centrifugal pumps in
which the passages are formed like those of an outward flow
turbine reversed ; these have also been arranged similarly in
series for high lifts. Low first cost and upkeep and their
capability of dealing with very large quantities of water in
which solid matter may be in suspension, are the chief advantages
of centrifugal pumps.

Where large volumes of air at a slight pressure are required
for ventilation of mines and buildings the form known as a fan
is almost exclusively employed (see Nos. 677-679).

Hydraulic Rams. In these machines the temporary rise in
pressure which results when the flow of water through a long
pipe is suddenly arrested is employed to raise a small quantity
to a considerable height. The first to make a practical applica-
tion of the principle was John Whitehurst, who in 1772 took
advantage of the use that was made of a cock at the ground
floor of the house, in order to raise water to a cistern on the
upper floor. In 1796 J. M. and J. E. de Montgolfier indepen-
dently invented the ram and made it self-acting by using, in
place of the cock, a valve loaded so as to open again after the
water had come to rest (see No. 681). Rams are now constructed
which will lift water from a different source to that whence
they obtain their power so that a dirty stream may be utilised
(see No. 682). To raise water in quantity rams have been con-
structed with the momentum valve operated quietly by com-
pressed air. Rams usually have a low efficiency, but require
little attention and maintenance.


607. Photographs of current wheels. Presented by H. W.
Dickinson, Esq., 1913.

These wheels, known as naura of which there are four altogether, are
situated in the River Orontes at the ancient city of Hama, Syria. The
wheels lift water for irrigation and domestic purposes in pots attached to
the rim. They are driven by float boards on the rim dipping into the stream.
The wheels are wholly of wood and the largest is said to be 70 ft. diam.


608. Model of scoop wheel (working). (Scale 1 : 10.) Con-
structed by Mons. P. Regnard, 1899.

This is a modern form of the "tympanum," which was an ancient water-
raising appliance when described by Yitruvius, in the first century A.D. It
consisted of a horizontal drum divided into four chambers by radial parti-
tions, and partly immersed in the water that was to be raised ; when the
drum was rotated, water entered each chamber by an opening at the circum-
ference, and afterwards escaped through another opening along the main
axle. I)e la Faye, about 1730, replaced these chambers by pipes bent to an
involute curve, thus greatly increasing the efficiency by reducing the useless
circumferential velocity given to the water.

About 1830, Cave brought the machine to the present form by fitting the
drum with partitions curved to an Archimedean spiral, by the use of which


the water is raised vertically through equal heights for equal angular move-
ments of the wheel, so that the resistance is uniform. Cave constructed
several of these wheels 23 ft. diam, 3*28 ft. wide, which were immersed 4 ft.
in the water to be raised. They were driven at a speed of 10 rev. per min.
by spur gearing, as shown, and are stated to have raised 8,800 gal. of water
per min. to a height of 3- 28 ft. with an efficiency of 85 per cent.

As wheels of this kind can only raise water to the height of their axles,
their use is restricted to low lifts ; also, any temporary lowering of the head
water in no way reduces the power required, and their effective speed is very
limited. On the other hand, they have no inferior limit of speed, and can
pump any kind of water without undue wear, while, under suitable condi-
tions, their efficiency is high. M.3045.

609. Model of scoop wheel. (Scale 1 : 25.) Made from a
drawing supplied by J. L. Pierson, Esq., 1913.

This scoop wheel, which resembles an undershot water wheel reversed, is
used for raising water in low lifts, e.g., as required in the drainage of low-
lying land. It has been but little used in this country, except in the Fen
districts, but has attained a high development in Holland.

The scoop wheel represented is one erected in 1896 at Keizersveer, on the
southern mouth of the Maas. The maximum lift here is 1'4 m. (4-6 ft.) ; the
wheel is so situated that 0*19 of its diameter is immersed, and the plane of
the scoops makes an angle of about 13 deg. with the radius. The number
of scoops is such that their distance apart at the circumference gives quiet
and regular action.

The wheel is 7'5 m. (24'6 ft.) diam. by 2-5 m. (8'2 ft.) broad and has
22 scoops, which are consequently 1*07 m. (3*5 ft.) apart on the circumference.
The wheel is built up on 3 cast iron spiders bolted together with distance-
pieces, and keyed to the shaft. The scoops are of sheet iron supported by
flat iron arms 120 mm. (4'72 in.) by 16 mm. (0*63 in.) made in the form of
frames with angle-iron bearers ; of these there are two in the width, bolted
to the spiders and to rings of the same section situated near the circum-
ference. The arms are stayed by bars of the same section bolted to the
spiders. In order to insert the scoops between the rings, each is made in two
parts, with a butt strap down the middle. The scoops stand back 5 cm.
(2 in.) from the faces of the wheel pit; wooden and sheet iron extension-pieces
are bolted to the edges so as to leave a clearance of 5 mm. (0'2 in.) only. The
wheel is driven by an engine with a pair of horizontal cylinders working at
80 Ib. pressure. The speed is reduced by mortice wheel and pinion, in the
ratio of 1 : 14, to 4 rev. per min., at which speed the water raised amounts to
250 cub. m. (8,830 cub. ft.) per min. Tests in 1898-9 showed a steam con-
sumption of 9-6 kg. per indicated h.p. per hour, and an efficiency of
58 per cent.

The delivery side of the wheel is provided with a swinging flap which
serves to hold up the water in the interval between one scoop's delivery and
the next. The wheel pit is provided with dock gates and sluices so that it
can be emptied for repairs, etc.

The Dutch scoop wheel is wider on the face than most of those used in the

Fens. The wheel at Pode Hole is 5 ft. wide and that at Southery 2 ft. 7 in.,

while many are only 12 in. to 15 in. wide ; but they are run faster than the

Dutch wheels, e.g., a 40 ft. wheel runs at 4 rev. and a 24 ft. wheel at 6 to

rev. per min. Inv. 1912-13.

610. Models of Chinese pumps. (Scales 1 : 12 and 1 : 24.)
Received 1862 and 1895.

These illustrate a form of pump frequently used for irrigation in China.
There is a long inclined trough dipping into the lower water at one end and
reaching above the higher level at the other ; in the trough is the lower half


of an endless chain provided with float boards just fitting it and returning
over a spoked axle at each end. The upper axle in one model is provided
with cranks driven by men working connecting rods, and in the other by an
ox turning a gin with wooden crown gearing. M.1670 and M.2190.


611. Reproductions of Roman pumps. Received 1914.

These are reproductions of two plunger pumps discovered on the site of a
foundry at Bolsena, Etruria and now in the British Museum. In some
respects the originals have not been followed, e.g., the reproductions have
been made in section, the better to show constructional details. The wooden
supports are conjectural. No date can be assigned confidently to the
originals ; possibly they are as early as the 1st century A.D.

The pump barrels, plungers, rising main, &c., are separate bronze
castings, probably made by the cire perdue method. The connections are
made by socket joints apparently soldered. There is good evidence of parts
having been turned on the outside but nothing can now be gathered as to
whether the barrels, &c., were bored. Each plunger has a knuckle joint with
socket for the rod which must have been actuated from a rocking beam
above ; what appear to be the journal and socket for this beam are shown in
one instance. The plungers are exceptionally short and there is no evidence
of any packing so that leakage must have been excessive, but the design is
good in that it gave a continuous discharge.

In the larger pump the valve seating is a disc -with an eccentric hole
covered by a clack valve which, from its likeness to a coin, was known by the
Greeks as 'ao-a-apiov. This clack hangs -loosely on a stud riveted in the
seating and burred over slightly to prevent the clack coming off. The
plungers are 1 * 35 in. diam. and the stroke was f> 1 in.

In the smaller pump all the valves are of the drop type ; a pin through
tho stem prevents the valve rising too far. In the case of the foot- valve, its
seating with the guiding ribs is soldered in; in the case of the delivery
valve, ribs are cast on the interior of the pipe and a guide for the valve
spindle soldered to them. The plungers are 1 in. diam. and the stroke was
3 -25 in.

(See British Museum Handbook to Greek and Roman Life, p. 110:)

Inv. 1914 702 & 703.

612. Engraving of London Bridge waterworks. Presented
by C. K. Eley, Esq., 1910.

This print shows, generally, the arrangements employed for 240 years at
Old London Bridge for supplying the City with water from the Thames.

The original scheme was due to a Dutchman named Peter Morice, who in
1582 obtained from the City a lease for 500 years at the rent of 10s. per
annum of the arch nearest the City end of the bridge. Two years later the
second arch was similarly leased, and in 1701 the third also, when the under-
taking was converted into a company.

The print shows one unit of the plant installed by George Sorocold at
the latter date. A tide- wheel, 20 ft. diam. with 26 floats 14 ft. long by
1-5 ft. deep, was raised and lowered to suit the state of the tide by mechanism
patented in 1693 by John Hadley. The wheel was supported on bearings
near the fulcra of two levers 16 ft. long, which were operated by pitch chains
and gearing in the ratio 1 : 68, so arranged that one man could work both.
In practice, however, it was found to be superfluous, and was not used. On
the axis of the tide-wheel were two cog-wheels, each gearing in the ratio
1 : 2*2 into a lantern wheel on the fulcrum axis. This was coupled to a four-
throw crankshaft driving, by connecting rods and beams, 8 pumps 7 in. diam.
by 2-5 ft. stroke drawing water from the river and forcing it to a height of
120 ft. The maximum speed of the tide- wheel was 6 rev. per min. The
efficiency of the pumps was about 60 per cent.


The plant remained in operation till 1822 when the bridge was removed
to give place to the present one. M.3753.

613. Model of Cornish mine pumps. (Scale 1 : 12.) Made
by J. Arthur, Esq., 1843.

This is a general representation of the complete arrangement of pumps
employed in a deep mine and is consequently not accurately to scale.

The work is performed by a single-acting condensing steam engine, the
beam of which projects through the end wall of the engine-house, so that the
outer extremity is over the mine shaft ; here also are the timber sheers, for
use in lowering the pumps and during repairs, while they also carry the
stationary ends of the radius links of the parallel motion guiding the main
pump-rod. This rod is built up of heavy square timbers, and extends nearly to
the bottom of the shaft ; its weight is largely counterbalanced by a loaded
rocking beam, or balance-bob, usually arranged at the surface and not as
shown in the model.

The lowest pump is of the bucket type at the bottom of which is a
strainer, and some little distance above it a box containing one or more non-
return or suction valves ; above them is the bucket, which also contains valves
and is worked by a rod passing up to its rising main and connected by
bracket pieces to the sides of the main pump-rod or spear, and at the top of
its rising main delivers into a cistern in the shaft. From this cistern rises a
vertical pipe, to the side of which is connected the barrel of a plunger pump ;
the plunger is bolted to the side of the main pump-rod, while the valve boxes
are arranged in the rising main, access being given by side doors. This rising
main may extend right to the surface, or to an adit; but, if the lift is
excessive, a similar pump takes it tq the next stage and so on, thus avoiding
excessive pressure or concussion on the valves and pipes. M.2652.

614. Models of mining pumps. (Scale 1 : 8.) Made by
Carl Schumann, 1851.

In each case the pump is of the bucket type, and has a single foot valve
at the bottom of the working barrel, while the pump-rod passes up through
the delivery pipe. In one of the examples the pump and its pipes are made
in cast iron; the latter have socket joints rendered tight by the use of hemp
and metallic lead ; in the other two examples the pipes are of timber hooped
with iron, and are usually made from tree trunks bored out. The various
lengths are socketed together and retained by three timber dogs at each joint ;
the working barrel is in iron, but the valve boxes are in wood and have side
doors ; in all cases the pumps and pipes are shown supported by timber
beams. . M.1405.

615. Cornish pumping engine (working). Lent by
Messrs. Harvey & Co., 1862. Plate. X., No. 3.

This is a small example of a type largely employed in waterworks, and
also, with a slight variation in arrangement, for mine drainage ; it is an
improved form of Watt's single-acting beam pumping engine (see No. 57).
A cylinder is situated under one extremity of the beam and a plunger pump
under the other ; the air pump, condenser, and feed pump are arranged
between the main pump and the beam centre, while on the other side is the
plug rod for actuating the valve gear.

Watt's parallel mation is employed at both ends of the beam, but for
mine pumping engines the motion is required for the cylinder end only, the
pit rods being connected directly to the beam. The automatic valves of the
steam cylinder are three in number : the steam valve, the equilibrium valve,
and the eduction valve, while a fourth valve the main steam valve is
provided for cutting off the supply of steam from the boiler when stopping
the engine, etc. The closing of the steam valve, of the equilibrium valve,


and of the eduction valve is effected by tappets on the plug rod; but
the equilibrium and eduction valves are interlocked by an ingenious
arrangement of two intersecting quadrants, set to prevent the possibility of
both valves being opened together. The opening of the steam and eduction
valves is controlled by a cataract gear, placed below the engine platform and
actuated by the plug rod. It consists of a plunger, working in a fluid, e.g., oil
or water, and connected to the valve catches and so lifted by the descending
plug rod. It is afterwards free to sink, the water or oil escaping through an
orifice that is adjustable for varying the time interval.

The engine is single-acting, the steam driving the piston down while the
lower end of the cylinder is in communication with the condenser. During
this stroke work is done in lifting the heavy plunger, and drawing into the
pump a volume of water from the suction main. At its termination the
steam and exhaust valves are closed by the tappets, and the equilibrium
valve opened, the latter putting the two ends of the cylinder in com-
munication, so that the piston is drawn upwards by the weight of the pump
plunger, which in its descent also forces the water in the pump through the
delivery valves into the rising main. At the completion of the up -stroke of
the piston a tappet closes the equilibrium valve, and so by cushioning
quietly stops the downward motion of the plunger, when there is an interval
of rest until the cataract plunger has descended far enough for it to lift the
catches that retain the steam and eduction valves closed, and on these
being released the down-stroke at once recommences. The cataract secures
that a definite interval shall elapse at the end of the stroke, and so gives a
ready and exact means of regulating the number of strokes made by the
engine per minute.

The example shows a cataract for the steam and the eduction valves
only, the equilibrium valve opening when the intersecting 'quadrants clear
one another. It is usual in engines of any size to apply also a separate
cataract to the equilibrium valve. This enables the engine to make a pause
at the end of the up -stroke as well as that of 'the down- stroke of the piston,
to give time for the main pump valves to close quietly and for the pump
rods to stop quivering.

Some very large engines of this type have been constructed, e.g., one
built in 1858 had a steam cylinder 112 in. diam. This example has a steam
cylinder 5 in. diam. and a plunger 4 in. diam., both with a stroke of 15 in.

Inv. 186226.

616. Models of Rittinger pumps (working). (Scale 1 : 5.)
Made by J. Schroder, 1892 and 1901.

This class of pump, in which the plunger is stationary and forms a con-
tinuation of the rising main while the pump barrel is moved up and down by
the spear rods, was introduced in 1849 by Heir P. von Eittinger at some
mines near Chemnitz, but the idea had to some extent been anticipated in the
"telescope " pump designed by Herr Althans in 1846.

One of the models represents a single-acting pump, and has only two
valves, while the other is double acting and requires three valves. In both
cases the rising main is provided with an air vessel and a retaining valve, and
terminates in a fixed hollow plunger upon which the pump barrel slides. The
lower end of the barrel is formed into a hollow plunger, which works through
a gland in the suction pipe, which, in the case of the double-acting pump, is
fitted with a suction valve.

In the single-acting example, during the up-stroke of the barrel, the
water displaced by the stationary plunger at the end of the rising main is de-
livered through it, and prevented from return during the downward stroke of
the barrel by the retaining valve, the spear rods, consequently, always work-
ing in tension.

In the double-acting pump, during the upward stroke of the barrel,
delivery takes place as above, but in the downward stroke the lower plunger,
which is of larger area than the upper one, displaces more water from the


suction pipe than will fill the space left in the barrel by the withdrawal of the
upper plunger, the excess, therefore, passing into the rising main, so that in
this pump water is being discharged during both strokes, while, by suitably
proportioning the areas of the two plungers, the weight of the spear rods can
be employed as in the ordinary plunger pump. External gland packings are
used for both plungers, and the valves in the barrels are rendered accessible
by side doors. M.3172.

617. Suction and lift pump (working). Lent by Messrs.
Perreaux & Co., 1903.

This is a single-acting pump for working by hand power; being provided
with a glass barrel, as is sometimes necessary when pumping chemicals, the
course of the fluid and the action of the valves can be seen.

During the up-stroke of the piston or "bucket," the water above it is
carried upward, while beneath the bucket an empty space would be left, but
for the atmospheric pressure which forces the water up the suction pipe and
causes it to follow the bucket. Upon the commencement of the down- stroke
the water in the barrel is prevented from returning, by a valve at the bottom
of the barrel, but is allowed to pass through the bucket to its upper side, by
a valve within it from whence it is delivered at the next up-stroke.

The valves employed in this example are of the construction patented in
1856 by Mr. L. G. Perreaux, and are made entirely of vulcanised india-rubber.
The base of the valve is a stout annular flange, by which it is held, and the
passage is closed by two lips with thin edges which are forced together if the
pressure above them is greater than that below.

The pump shown is 2'5 in. diam. by 6-5 in. stroke; for larger pumps
the Perreaux valve is formed with 3 pairs of lips meeting at a common,
centre. M.3294.

618. Downton pump. Made by Messrs. J. Downton & Co."
Received 1911.

This type of suction pump was patented in 1825 by Jonathan Downton
and has been used largely on board ship. Its advantages are that with only
one pump barrel a number of superposed buckets, of length of stroke dimin-
ished in proportion to the number, are employed, so obtaining practically a
uniform delivery.

Three is the number of buckets used, and in the original design their rods
were telescoped one within the other, with offsets on two of them to operate
them by. In this example the rods are side by side, that of the lowest bucket
being in the centre ; this necessitates the upper two buckets having holes
through them, but no packing is needed. The upper ends of the rods terminate
in loops which slide in grooves in the top casing. The loops embrace cranks
at 120 deg. on a three-throw shaft, actuated by a flywheel and handle. The
suction valve is a simple clack hinged for convenience to the cover of the
valve box. The pump stands on a casting for conveniently bolting it to the
deck, etc. M.3939.

619. Model of a reciprocating pump. (Scale 1 : 4.) Lent by
Messrs. Pontifex and Wood, 1890.

Two suction and lift pumps delivering alternately are here arranged in a
cylindrical casing in a similar way to that patented in 1793 by Joseph Bramah
for a fire engine. The two buckets form a diametral plate and are capable
of being oscillated on the axis through 80 deg. by an external hand-lever.
Beneath the buckets, a sector of the cylinder forms a suction box provided

Online LibraryVictoria and Albert MuseumCatalogue of the mechanical engineering collection in the science division of the Victoria and Albert museum, South Kensington → online text (page 42 of 71)