a 50 ft. wheel giving as high as 54 horse-power. The illustration
is a No. 1 Warner’s galvanised iron overshot wheel, price 25_l._,
including framework and double action pump, with air vessel complete,
capable of lifting ½ gal. of water per minute 60 ft. high through
400 ft. of delivery pipe. The power of these wheels is not only
increased as the diameter increases, but also by increasing the width
of the blades; for instance, a Warner’s wrought iron overshot or high
breast wheel of 20 ft. diameter with blades 3 ft. wide, develops 11
horse-power, and the same diameter with 6 ft. blades very naturally
gives double (22 horse-power), but with only about 30 per cent.
increased cost.
[Illustration: 183. Improved Turbine.]
_Turbines_ are a form of water motor which require a head of water,
i.e. the water for propelling them must be supplied by means of pipes
from a height; for a moderate power, with the majority of turbines,
it should be not less than 12 ft.; the higher the head of water the
greater the pressure, and the smaller the turbine requires to be for
a given amount of work or power (this applies to all water motors),
consequently the cost of the motor is less, the pipes smaller, and
there is decided economy in the quantity of water used as the height
increases. The pressure of water in pipes is 1 lb. to the square inch
for every 2 ft. 4 in. in height (not allowing for friction); thus it
will be seen that the surface in a turbine upon which the pressure of
water is exerted, requires to be double the area with a 20 ft. fall
than with a 40 ft. fall for given power. A Warner’s 5 horse-power
turbine for 16 ft. fall uses 220 ft. of water per minute with a wheel
of 13 in. diameter, giving 377 revolutions a minute, and costing
60_l._, whereas a 5 horse-power turbine for 30 ft. fall uses 118 ft.
of water with an 8 in. wheel giving 853 revolutions a minute and
costs 45_l._ Fig. 183 shows a Warner’s (Redtenbacher Jouval) improved
turbine fitted and connected to a driving shaft. This turbine is
made to work with as low a fall as 2 ft., giving 1 horse-power, but
the cost is necessarily high. It will be seen from the illustration
(which is in section), that the water is made to pass between fixed
oblique blades or palettes, and strikes on the oblique blades of the
wheel beneath, these latter blades being at an opposite angle to the
fixed blades above; thus a pressure, varying with the height of head
of water, is directly exerted on every square inch of the blades of
the wheel and great power is obtained.
[Illustration: 184. Blake’s Ram.]
_Hydraulic Rams_ are self-acting water motors, for the supply of
water to great heights and distances; they require a fall of water
of 12 in. upwards, and are made to supply either the water that
works them, or to supply well water while being worked by a stream
of impure water; one of the best makers and authorities upon these
motors is John Blake, of Oxford Street Works, Accrington, Lancashire.
Fig. 184 shows a Blake’s ram of ordinary construction, for raising a
portion of the water that works it; a No. 2 (smallest size), price
12_l._, will raise 300 gal. per day, to say 800 ft. high; a No. 16
will raise 100,000 gal. per day. Fig. 185 shows a ram raising water
to a reservoir for general purposes.
[Illustration: 185. Blake’s Ram in use. 186. Haag’s Motor.]
A hydraulic ram is undoubtedly the most economical means of raising a
supply of water, either for a single residence or for a small town,
as they work day and night without attention (or intermittently if
desired), and work as well submerged as above water; but they, of
course, depend entirely upon a fall of water being obtainable, and
this fall or supply must be constant.
[Illustration: 187. Thirlmere Motor.]
[Illustration: 188. Hydraulic Blower.]
_Hydraulic Engines_ are made in various forms, being commonly worked
in a similar manner to a steam engine, water under pressure acting
upon the piston in place of steam. Fig. 186 represents a “Haag’s”
patent water motor adapted for a chaff-cutting machine; Fig. 187
a series of “Thirlmere” water motors, showing the capacities;
Fig. 188 a Bailey’s patent hydraulic blower, for chamber or church
organs, smiths’ bellows, &c. All these motors are manufactured by
W. H. Bailey & Co., of Albion Works, Salford, Manchester, and being
small and inexpensive, they are very suitable and convenient for
working sewing machines, knife cleaners, washers and manglers, and
any domestic machine that entails considerable labour. The power of
these motors varies with the pressure of water, if connected with
the town’s main (by arrangement with the water company), a very high
pressure is generally obtained.
A “Haag’s” motor, No. 2 (smallest size), gives from ¼ to ½
horse-power, 220 revolutions (of the flywheel) a minute, and costs
10_l._ A “Thirlmere” motor, No. 00 (smallest size) gives from
1/70th to 1/30th of a horse-power, and costs 2_l._ 2_s._ A Bailey’s
blower No. 1 (smallest size), at 50 lb. pressure, gives a boy power
with a 10 in. stroke, and costs 6_l._ 6_s._, and is suitable for a
chamber organ; these latter are made to work either vertically or
horizontally.
[Illustration: 189. Ramsbottom Engine.]
Fig. 189 is a “Ramsbottom” 3 cylinder hydraulic engine (Jno.
Ramsbottom, Saynor Road, Hunslet, _Leeds_). This is considered one
of the most efficient hydraulic motors yet made, and it possesses an
advantage in having no dead points (see Flywheel of Steam Engine),
and its action is exceedingly steady and uniform. The illustration
will acquaint the reader with its constructive details, which are
simple and few in number.
No correct idea can be given as to the cost of working these motors,
for as before explained, it depends entirely upon the pressure of
water obtainable.
_Steam._--Steam engines are made in very many forms, and it would
be impossible for us to describe even a small proportion of those
made; for small purposes they are most generally made having engine
and boiler combined, but where moderately high powers are needed,
and space has to be considered, it is found more economical and
convenient to keep them separate; the supply of steam from boiler to
engine being conveyed by a pipe. It might be here mentioned that it
is necessary that all steam chambers and pipes be coated or covered
with some non-conducting material, to prevent loss of heat and
consequent condensation of steam, and it is found advantageous to
keep the steam at as high a temperature as possible, to increase its
efficiency; with most large engines the steam is superheated (i.e.
heated to higher than its ordinary temperature) as it passes from
boiler to engine.
It is not our intention, neither would it be possible in our limited
space, to give a practical treatise upon the steam engine, but it
will doubtless be interesting and instructive to many if a general
description of the chief features be given. They practically consist
of the “boiler,” to which is attached the “feed pump,” “water gauge,”
“steam gauge,” and “safety valve.” The “engine,” which consists of
the cylinder and piston, “governor,” “cranks,” “eccentrics,” and
flywheel.
Boilers take many forms, but in actual principle consist of two
sorts, both being cylindrical, one being clear inside, and the
other nearly filled with flue tubes, which very greatly increase
the heating surface. The first mentioned, which is generally used
for large works, and is known as a Cornish boiler, Fig. 190, has a
cylindrical outer shell, within which is a smaller cylinder, the
space between the two, which is closed at both ends, containing the
water as shown. This boiler is fixed in brick-work, and the furnace
is situated within the inner cylinder. To increase the power of these
boilers, large water tubes are carried across the inside of the inner
cylinder (opening into the water chamber at each end) where the flame
and heat pass after leaving the furnace.
[Illustration: 190. Cornish Boiler. 191. MULTITUBULAR BOILER.
(SECTION)]
_Multitubular Boilers_ are generally those that are attached to
or combined with the engine, where space is a primary object
(locomotive engines have multitubular boilers). Fig. 191 shows the
arrangement of this boiler in a vertical position with horizontal
tubes (shown without the engine); they are also very commonly made
with vertical tubes. All boilers are, or should be, provided with
ample accommodation for removing the incrustated deposit, which forms
with moderate rapidity, as the water is continually boiling, and as
evaporation in a steam boiler is very rapid, the supply of water is
constantly being renewed, and each successive charge of water brings
its proportion of lime to be deposited. (For fuller details upon
incrustation and causes, see Bathroom.)
_The Feed Pump_ is a small pump of ordinary shape and construction,
situated near and worked by the engine, its purpose being to supply
water to the boiler when needed. Mechanism is provided for throwing
it in and out of gear as the water gauge indicates; it will be
readily understood that no means can be provided for filling a steam
boiler by hand, that is to say, it must be done mechanically, as no
loose cover can be provided.
[Illustration: 192. WATER GAUGE. 193. STEAM GAUGE.]
_The Water Gauge_ (Fig. 192) consists of two suitably constructed
cocks, both being screwed into the boiler one above and one below the
correct or average water level, a strong glass tube extending between
them as shown; the water level is necessarily the same in the glass
tube as in the boiler and consequently the attendant can see at a
glance when water is needed; the object of having cocks at each end
of the tube is to prevent the escape of water and steam by closing
the cocks should the tube be broken.
_The Steam or Pressure Gauge_ (Fig. 193) is a circular brass case
with a dial in front, somewhat similar to a clock; within the case
is a small curved tube made so as to be somewhat elastic, this tube
is in direct communication with the steam in the boiler. A somewhat
peculiar action is relied upon, which is, that as the pressure of
steam is exerted within this curved tube, it tends to straighten it,
and this, by a simple arrangement of wheels, causes the pointer to
move round the dial, which is provided with figures round its edge
showing the pressure in pounds (to the square inch) that is exerted
in the boiler as the indicator points to them.
[Illustration: 194. SAFETY VALVE. (SECTION)]
The utility of the safety valve (Fig. 194) is obvious. They are
invariably made so that by means of a weight or other device they can
be regulated to blow off at whatever pressure the engineer dictates,
the pressure being indicated by the pressure gauge.
Fig. 195 represents a cylinder with piston inside; the cylinder
should be encased with wood or some non-conducting material, or be
provided with an outer iron casing or “jacket,” the space between
the casing and the cylinder being converted into a steam chamber.
Whatever method is adopted, the object is to keep the cylinder from
losing its heat and to prevent condensation. The “ports” are openings
through which the steam passes; by means of “slide valves” the steam
is alternately admitted and expelled from each of these, so that the
opening which serves to admit steam on the instroke serves as an exit
for the steam on the outstroke, and the slide valves are worked from
the main crank shaft by valve gear and eccentrics.
[Illustration: 195. Cylinder, with piston inside.]
_The Valve Gear_ is the arrangement of rods that connect the
eccentrics with the slide valves.
_The Piston_ consists of a circular disc of metal made to most
accurately fit the interior of the cylinder; to this is connected a
rod as shown, called the piston rod, which is in direct communication
with the crank. It will be seen that when the steam is admitted into
one end of the cylinder the pressure causes the piston to travel
towards the other end; when the piston reaches a certain point
(called the dead point) the slide valve shifts and the inflow of
steam is changed to the other end, and this causes the piston to
travel back again, and so it continues; an instroke and outstroke
give one revolution to the crank and flywheel.
[Illustration: 196. ECCENTRIC.]
_An Eccentric_ (Fig. 196) is an ingenious piece of mechanism that
answers exactly the opposite purpose of a crank, viz. to convert a
rotary motion into a backward and forward movement. An eccentric
is a circular iron disc, with the main crank shaft passing tightly
through it, but the shaft does not pass through the centre; hence the
term “eccentric.” This disc is encircled and revolves within an iron
strap, which is attached to the valve rod or gear. It will be readily
seen that as the disc revolves it gives a reciprocating movement to
the rod, causing the slide valve to which it is connected to open
and close the ports in the cylinder, and the object in attaching
the eccentrics to the crank shaft is that the piston rod and valve
rods may have an equal and corresponding action, which it will be
understood is absolutely necessary.
[Illustration: 197. CRANK. CRANK. 198. DISC CRANK.]
_The Crank_ (Fig. 197), which on small engines is generally attached
to one end of the crank shaft, is one of Watts’ most famous
inventions (but which, however, was pirated from him), and its object
is to convert the backward and forward movement of the piston rod
into a rotary motion at the shaft. Disc crank plates (Fig. 198) are
now getting into favour as having a steadier action, and it is to all
intents and purposes a crank, but of improved form.
_The Flywheel_ is a heavy cast-iron wheel attached to the crank shaft
on the opposite end to the crank itself; it serves more than one
useful purpose, viz. giving great steadiness to the motion, assisting
propulsion to some extent by its momentum and carrying the piston
over the dead points (a dead point is the position which the piston
is in when it has finished one stroke and about to return just at the
time it becomes quite still for an instant, and this is called the
dead point, and it happens at the end of each stroke).
_The Pulleys_ are of two kinds, fast and loose; they are light wheels
about one-sixth the diameter of the flywheel, at whose side they are
attached to the extreme end of the shaft. They have broad flat faces
or rims, and their object is to carry the strap or belting which
transmits the power from the engine to the work. The fast or driving
pulley is the one that is secured to the shaft and revolves with the
flywheel; the loose pulley is the one that is not secured to the
shaft, and rotates loosely upon it when occasion demands; a forked
arrangement transfers the belting from the fast to the loose pulley
when it is necessary to stop the machinery, or vice versâ.
[Illustration: 199. Governor.]
_The Governor_ (Fig. 199) is another ingenious and important
invention of Watts, and serves a most useful purpose; it will be
understood that if when an engine was working with the full strain
of the machinery upon it, the belting was to break, the engine would
immediately begin working at an alarming speed, most destructive to
itself (this does not apply to engines, such as locomotives, that
have constant attention); the governor, as the name implies, controls
this. By referring to the illustration, it will be seen that as the
speed of the engine increases, the faster the governor rotates (it
being connected with the crank shaft); this, by centrifugal action,
makes the two balls fly out, and this causes a valve in the steam
inlet to partially close and so check the supply of steam from boiler
to engine, thus very naturally reducing the speed.
_Lubricators_ (self-acting) are provided wherever necessary, and it
is important that a motor of any description be well lubricated at
its wearing parts or wherever friction takes place; this reduces the
wear and tear to a minimum, and very greatly adds to the motor’s
efficiency.
_Steam_ is produced by subjecting water to heat, and so causing it to
evaporate; steam is commonly understood to be (by those that have not
studied the subject) a white watery vapour, whereas it is exactly the
reverse, it is practically as dry and colourless as the atmosphere,
and possesses similar characteristics in its unlimited expansibility
and compressibility; it only assumes the white vapoury appearance
when it escapes in the air which is at a lower temperature than
itself, as it then condenses into its original form, water; if steam
was ejected into a compartment that was heated to say 220° the steam
would retain its own form and be quite colourless and invisible. The
expansive power of steam is put to good purpose in what is known
as the “cut-off” and also in compound engines; the cut-off is an
arrangement whereby the steam is cut off from the cylinder, when the
piston has been impelled ½ or ⅝ of a stroke, and the expansion of
the steam completes the stroke. In compound engines (which are large
and have 2 cylinders) the steam, after doing service in the first
cylinder, is conducted to a second of greater diameter, where by
expansion it exerts a lower pressure, but on 2 or 3 times the piston
area, so giving units of work equal to the first cylinder. Engines
are now made with 3 cylinders, thus fully utilising this economical
plan.
_Horse-power._--When steam engines first came into use they were
applied to work previously done by horses which worked the mills; it
was, therefore, convenient and desirable to say what number of horses
an engine would supersede, hence the term horse-power, which means a
capacity to produce a mechanical effect equivalent to raising 33,000
lb. one foot per minute. The indicated horse-power of an engine is
the pressure exerted by the steam on the piston without allowing for
friction, the indicated horse-power is therefore higher than the
power that will be realised; the nominal horse-power is that which
is obtained by measurement of the cylinder and piston area, and is
a commercial standard, but a deficient one, and most makers’ lists
now show engines which by improvements will give 1 and 2 actual
horse-power higher than the nominal.
The makers of steam engines might be named “legion,” but the two
following are firms of repute, making somewhat a specialty of small
motors. Fig. 200 shows a combined vertical engine and boiler complete
with feed pump and water tank base, and requiring no fixing (makers
Hindley & Co., 11 Queen Victoria Street, London, E.C.); the boiler
is multitubular (vertical tubes) and the sizes vary from 2 to 6
horse-power, costing from 62_l._, to 122_l._; if coal fuel is not
available, and it is desired to burn wood, peat or inferior fuel,
it is usual to have the boiler a size larger costing from 3_l._ to
10_l._ extra. It will be noticed that the water tank forming the
base, causes the feed water to become heated. The plan of heating
the feed water is now universally followed, as it will be understood
how disadvantageous it is to pump cold water into the boiler when
it is in full work. Feed pumps are now made to pump boiling water
if required. Fig. 201 shows a Hindley’s horizontal steam engine
complete with pump, but without boiler, made in sizes from 2 to 15
horse-power, costing from 24_l._ to 100_l._
[Illustration: 200. Hindley’s Vertical Engine. 201. Hindley’s Engine.
202. Tangyes’ Vertical Engine.]
Fig. 202 is a Tangyes’ (Tangyes, Limited, 35 Queen Victoria Street,
London) vertical steam engine and boiler complete, and mounted on a
wheeled bed for portability, the cost being 2 horse-power 63_l._, 3
horse-power 79_l._ Fig. 203 is a Tangyes’ vertical engine without
boiler, and on firm base, price, 2 horse-power 22_l._, 3 horse-power
29_l._, including feed pumps.
We have purposely omitted the use and description of condensers, as
they are only of real use with very large engines (except with marine
engines to which condensers are always fitted as the cold water for
condensing is at hand in unlimited quantities); a good use to which
the exhaust steam can be put is to heat the feed water; Fig. 204 is a
Tangyes’ feed-water heater; it will be seen that the heating medium
is the exhaust steam from the engine. These are made with brass
tubes, which on account of great expansion and contraction will not
permit the incrustation to adhere to their surface, and it falls in a
scaley and sandy mass to the bottom where a mudhole and handhole are
provided for periodical cleaning; the cost of these varies with the
size of the steam exhaust pipe, for a 2 in. pipe the price is 13_l._
If the exhaust pipe is carried any distance, it must be thoroughly
well insulated, or the steam will condense, and the water will
run back into the cylinder; this really occurs to a small extent
with the best management, consequently a “steam trap” is used, the
object of which is to discharge water resulting from condensation.
The management of a small steam motor is practically simple, but
moderately constant attention is needed; it must be seen that the
supply of water is kept up in the boiler, the water and pressure
gauges must be occasionally looked to, and the lubricators must be
replenished regularly. The want of skilled attention is felt when a
small accident or breakdown occurs, but this of course applies to all
motors.
[Illustration: 203. Tangyes’ Vertical Engine without Boiler. 204.
Tangyes’ Feed-water Heater. 205. Davey’s Safety Motor.]
_Davey’s Safety Motor_ (Fig. 205) is a revival of the atmospheric
engine of 1705 in general principle, but with various decided
improvements. The word “safety” is used advisedly, as there is no
pressure exerted by the steam higher than atmospheric pressure (15
lb. to the square inch), consequently it is as non-explosive as a
teakettle, and no steam gauge or safety valve is required and the
motor can be placed in charge of the most unskilled attendant. The
power is obtained by the condensation of steam producing a vacuum
and thereby making available the pressure of the atmosphere. This
motor has a cylinder and piston; as the piston is proceeding on the
outstroke the cylinder is charged with steam at low pressure; at
the proper moment a jet of cold water is admitted which instantly
condenses the steam, producing a vacuum, the pressure of the
atmosphere immediately asserts itself outside of the piston pressing
it back on the instroke, after which the action is repeated; so it
will be seen that the piston relies upon the momentum of the flywheel
for the outstroke and the pressure of the atmosphere (15 lb. to sq.
in.) for the instroke. This is an economical motor, the consumption
of fuel (gas coke) averaging 6 lb. per horse-power per hour, and the
makers claim that the cost of fuel and water (if the latter has to
be paid for) combined is less than the cost of gas for working a gas
engine for a given amount of work.
These motors are also made to work with a pressure of steam about 2
lb. above atmospheric pressure, and this can then be utilised for
steaming purposes, such as for cattle foods, &c.; this also applies
to any steam motor. The cost of these motors is for ¾ indicated
horse-power 45_l._, with a 2 ft. flywheel 160 revolutions a minute,
or a larger size, 4½ indicated horse-power, 100_l._, with a 4 ft.
flywheel.
_Gas._--Gas engines are now occupying considerable attention and
receiving general favour; the attention needed in working these
motors is comparatively nil, and they admit of such exact regulation
that there is practically no loss of power and fuel, for in reducing
speed or work the supply of fuel (gas) must first be reduced. A
noticeable feature is the extreme cleanliness, as there is no furnace
and stoking, no boiler safety-valve nor pressure gauge, &c.; and
it is a common thing to find these motors left for hours without
attention, as the supply of fuel is unvarying and self-acting
lubricators of good make only require attention about once a day.
A still further and important advantage possessed by these motors
is the almost instantaneous starting and stopping, making them
particularly well adapted for electric lighting apparatus in event
of a sudden darkness arising. The majority of these remarks, it will
be noticed, apply to many motors. All gas engines are practically
worked upon the same principle, but differing in detail; there is,
however, a practical difference in one respect, and that is, that
some consume the gas in its ordinary state as supplied from the gas
mains, whilst others consume it after the piston has first compressed
it; the latter is undoubtedly the most effective in results, as the
difference may be compared to igniting gunpowder in the barrel of a
gun in a loose state, or after it has been rammed close.