« AnteriorContinuar »
2- Elementary explanation of the action and working of steam in a cylinder.—Essen
tial parts of an engine. Introduction, exhaustion; absolute pressure; back pressure; effective pressure. Condensing and non-condensing engines. Condenser, vacuum. Back pressure in the cylinder compared with the pressure in the boiler. Double-acting engine; single-acting engine; atmospheric engine. Mechanical work. Kilogrammeter; horse-power. Work of a force
cting in the direction of the motion, or otherwise. Graphic representation of the work of a variable or constant force. Mean effort of a variable effort. Moving force, resisting force, and effective force of steam in a cylinder. Advantages of the
condenser. Effective power of engines in the different couditions of working. 3.-Transmission of movement from the piston to the shaft.-Connecting rod and
crank. Dead centers; travel of the piston from one dead center to the other; top and bottom of a cylinder; names of the dead centers and of the strokes of the piston. Simultaneous positions of the crank, piston, and commecting-rod; half-stroke. Angularity of the connecting-rod; its influence. Summary no
tions of the correlative movements of the piston and the shaft. 4.-Elementary explanation of the regulation of engines.-Expansion: change of mo
tion of the piston. Limited admission; leads; compression; clearance. Graphic representation of the effective work of the steam in the cylinder, taking into ac
count the adjustment of the valve-gear. Advantage of the exhaust-lead. Curves of expansion. Graphic construction of the general equation Pya = P.Vo=
constant. Particular case where I = 1; that is, the case most often met with. Theoretical expression of the work of steam during expansion. Advantages and inconveniences of expansion. Action of the steam-jacket.
Complete description of a screw-engine. Classification of the principal systems.
1.--- General description of an elementary screw-engine. 2.- Mode of action of detail parts. — Transmission of movement. Distribution of steam.
Jet and surface condensers. Advantages of surface condensers. Boiler-feeding
apparatus. Bilge-pump. 3.-Classification of marine engines, principal systems.-Classification. Geometrical
description. Beam engine. Oscillating engine. Direct-acting engine. Backacting engine. Trunk engine.
Complete erposition of the distribution of the steam by the slide-valve or by separate cut-off
1.- The eccentric.-Its working. Description of the transmission of movement by a
fixed eccentric; by eccentric with variable angular advance. Example of sys
tem of hooking-on gear. 2.-Slide-valves.- Definitions. Valve-faces; valve-seats. Two kinds of slide-valve.
Elementary description of the working of a three-ported slide-valve. D-valve; explanation of its working. Comparison of the working of the two kinds of
slide-valves. Adjustment of a slide-valve; stroke; attachment of the valve-stem. Angle of
lead. Lap. Total area of ports. Results of the adjustment of a slide-valve. Steam-lead. Greatest opening of the ports. Wire-drawing steam. Exhaust
lead. Compression. Résumé of the functions of the slide-valve. 3-Mechanism of the reversing-gear.—Principle.of the reversement of motion. Means
of carrying out this principle. Geometrical study of the reversing mechanism. First system: Single eccentric, with variable advance : (1) by means of a slip
eccentric; (2) by means of an adjustable eccentric. Mazeline's system.
Second system: Two eccentrics, with fixed advance: (1) drop-hook motion; systein
of Creusot; (2) by link-work. Stephenson’s link. 4.-Variable cut-offs. — Variable cut-offs driven by cams; by an adjustable eccentric,
the cut-off valve being wide open at the end of a stroke; at half-stroke. Cutoff driven by a fixed eccentric, the stroke of the expansion-valve being variable, and the valve opening wide at the end of a stroke; at half-stroke.
Steam-generators. 1.- Division and classification, 2.-Ordinary rectangular boiler, tubular boiler, return tubular boiler, low-pressure
boiler. General description of the accessory parts. Fire-tools. Working of a boiler. Principal dimensions of return tubular boilers, two types. Rectangular
boiler. Arrangement of boilers. 3.-Details of construction of boilers and their parts.—Mode of connecting the fixed
pieces; bolts, viz, tap-bolts, stud-bolts, dowels, rivets. Boiler-plates ; mode of
assemblage. Angle irons. Dead plates, grates, bearer-bars, lugs, bridge-walls. Diagonal bracing, longitudi
nal and bridge-bracing. Man-hole plates. Tubes ; their fastening on the tubesheet, ferules; beading : movable tubes. Langloir's system. Gautelme's system. Toscer's system. Fixed and movable pipes. Natural draught produced by
the smoke-pipe. Forced draught. Check-valves. Glass water-gauge; putting the glass tube in place. Gauge-cocks
Blow-off cock. Safety-valve. Dimensions and load of a safety-valve. Safetyvalve for small boilers at high pressure. Atmospheric valve. Stop-valve.
Communicating-valve. Dry pipes and superheaters. Pipes and valves. Joints with fixed and movable flanges. Soldered and riveted
flanges. Slip-joint. Single-way, two-way, and four-way cocks. Hollow-plug
cock. Sea-cocks. Kingston valve. 4.-Cylindrical boilers.—Return tubular and high-pressure boiler. General description
of boiler with appendages. Arrangement of brace-tubes. Method of joining the
boiler-plates. Principal dimensions. 5.-Short description of the principal types of boilers in use.—Tubular boiler. Side
flue bojler. Cylindrical boiler for launch. Belleville boiler for launch; working of this boiler. Details of feed regulator.
Management of engines and boilers.
1.-Working the engine.-- Preparations for starting. Blowing through and turning
Direct blowing through of the condenser. Starting. Increasing or reducing speed. Final stop. General care to be given to the engine while in
motion. 2.-Fuel and combustion.-Calorific power. Evaporative power. Air of combustion.
Space occupied by a given weight of coal. Manner of burning of the fuel.
slag: General character of coal; coal, properly so called; rich and poor coals; hard or
compact coals. Anthracite. Lignite. Conglomerate or pressed fuel. Bri
quettes. 3.—Management of fires.-Prining the furnaces. Lighting. Care of the fires while
the engine is in motion. Increasing and moderating fires. Banking fires.
Forcing fires. Hauling fires. 4.-Feeding and blowing.–Filling the boilers. Keeping up a constant level. Feeding
during a stop. Salts in solution in sea-water. Action of the salt in the boiler. Deposit. Measure of density; salinometer; testing salinometer. Effect of deposits; means of prevention; blowing off. Losses occasioned by it. Regula
tion of the blowing off. Emptying the boilers. 5.–Pressure; production of steam.—Keeping up the pressure. Increasing and dimin
ishing pressure. Coal consumed, (1) in terms of the evaporation per given
weight of coal; (2) per unit area of grate in a given time. 6.-Accidents.–Foaming: causes; effects; remedies; means of prevention. Priming:
causes ; effects; remedies; means of prevention. Leaks: their consequences.
measures to be taken.
Principal types of ordinary engines in use, of Woolf's or compound engines, and of boat
engines. Oscillating paddle engine. Compound inverted-cylinder engine. Woolf's threecylinder back-acting engine. Inverted-cylinder non-condensing launch engine. Silent launch engines.
Description and details of various parts of the machinery. 1.- The cylinder and its appendages.-Cylinder; valve-seat; ports; bottom; cover.
Clearance. Ratio between the stroke of the piston and the diameter of the cyl
inder. Steam-jacket; lagging. Cylinders and steam-passages of Woolf engines. Continuous-expansion engine. Compound engines, with, cranks at 90°. Three-cylinder engines, with cranks at 90° and 1350. Piston-rod stuffing-boxes for horizontal and vertical cylinders. Laying up the packing. Stuffing-box capable of adjustment while under way. Cylinder relief-valves. Blow-through cock. Ordinary balance-pressure lubri
cator. Thibaut's lubricator. Roscoët's lubricator. 2.—Steam piston, packing, rods.—Spider of piston; piston-rings; follower. Anti-fric
tion piston-rings. Piston-rods; fitting of the rod in the piston and in the cross
head. Trunks; their adjustment with the piston. 3.-Slide-valves. - Review of the classification. Ordinary three-ported slide-valve.
Object of equilibrium packings. Box-valve on Mazeline's system. Doubleported slide-valve. Dupuy de Lôme's long D-valve. Rectangular long D-valve
of Indret. Relative merits of different methods of distribution, 4.-Starting and reversing gear.- Review of the classification. Mazeline's starting
gear. Stephenson's link; explanation of the action of the link. 5.–Valves: regulators and apparatus of variable expansion.—Throttle-valve. Stop
valve. Throttle-valve in boat engines. Governors: two classes. Adaptability for marine engines. Conditions that must
be fulfilled by a governor used in a marine engine. Farcot's governor: description, conditions of equilibrium, and mode of action. Servo-moteurs : geometric
description of a serro-moteur applied to an engine. Apparatus for variable cut-off; their use. Review of the classification. Expansion by means of gridiron-valve and adjustable eccentric. Meyer's expansionvalve. Expansion by means of a butterfly-valve moved by a fixed eccentric of
variable throw. Expansion-valve regulated by a link. 6.—The condenser and its parts.-Analysis of the processes of condensation by injec
tion and of surface condensation. Weight of the injection water; temperature of jet condensation. Weight of cold water in surface-condensers; temperature : area of condensing surface. Advantages and disadvantages of surface con
densers and reasons for employing them. Form and volume of jet-condensers. Sea-cock and injection-pipe. Injection
valve. Bilge-injection. Air-pump; description ; volume for maintaining a proper vacuum in a given con
denser. Description of lifting air-pump. India-rubber valves. The Indret jet-condenser for a screw-engine. Double-acting air-pump. Hot-well; relief
valve; outboard-delivery valve. Discharge-pipe. Complete description of a surface-condenser for an engine of the Indret type.
Method of action of the surface-condenser. Circulation of the steam and of the cold water. Methods of fixing the tube in the tube-sheet. Distilling-apparatus
for fresh water. 7.-Transmission of movement.-Mazeline's cross-head. Cross-heads of the Indret
type. Connecting-rou, type Indret, with club ends. Mazeline’s connecting-rod, stub
end. Cross-head guides, cross-head, and connecting-rod for an inverted cylin
der engine. Mazeline's crank-shaft bearings. Bearings of the “Forges et Chantiers" type.
Crauk-shaft; angle between the cranks. Valve-gear counter-shaft.
Siphon lubricator. Lubricator with valve. Crank-pin and wrist-pin lubricators. 8.-Apparatus for feeding and for pumping out bilge.-Feed-pups. Donkey engine;
its valve chamber. Giffard's injector; its principle. Description of the Giffard feeding apparatus. Behrens's rotary engine. Bilge-pumps. Jet-bilge pump. Friedmann's ejector. Centrifugal pump.
1.-Paddle-wheels.-Geometrical description; moile of action. Causes of loss of
power; slip: Elements of paddle-wheels. Position and number of wheels. Advance and slip. Rolling circle. Different systems of paddle-wheels; wheels
with feathering paddles. 2.—The screw.-Definitions. Mode of action. Causes of loss of power; slip. Ele
ments. Position and number of screws. Advance and slip. Fixed and variable pitch. Classification and description of various screws; type Mangin.
Screw with spherical hub and bent-back blades. New model of screw. Line of shafting. Cardan's coupling and hand-turning gear. Movable coupling
and break. Stern-pipe and screw-shaft. Thrust-bearing. Stern stuffing-box. Outboard bearing of screw-shaft.
Regulation, work, and employment of marine engines. 1.-Curves representing the motions of the slide-valve.-Representation of the simul
taneous movement of the piston and slide-valve; curves of piston-speeds. Motion curve of a 3-ported slide. Variation of the angle of lead. Relative positions of piston and slide-valve. Motion curve of a D slide-valve. Determination of the action of a slide-valve by means of the motion of any given
point in the valve. Determination of the elements necessary for a graphic representation of the motion of a slide-valve. Determination of the dead centers of the piston and slide. Determination of the lap. Operations necessary for determining the
relative position of the piston and slide-valve. Drawing of a sketch of the arrangement and position of the ports. Analysis of
the operations of the slide-valve. Drawing of a D-valve. Adjustment of the ralve-stem and angle of eccentric by means of a motion-diagram. Case of a link.
Observations relative to the valve-diagram for a backing motion. 2.-Work of the steam in the engine.—Theory of the indicator. Primitive indicator
of Watt. Drawing of a diagram from the analysis of the working of the slidevalve. Measurement of the pressure by means of the indicator diagram. The surface of the diagram represents the effective work of the steam upon a square
centimeter of the surface of the piston. Garnier's indicator, new model. Richards's indicator. Fitting the indicator on an engine. Adjustment of the indicator. Disarrange
ment of the indicator. Representation of an indicator-curve. Tracing of the
atmospheric line. Calculation of the mean effort on the pistons. Mean vacuum in the cylinder; cor
rection by means of the barometric pressure. Calculation of the power of an engine by the mean effort found by the indicator-curves. Nominal, indicated, and actnal horse-power. Work on the shaft. Old formula for nominal horse
power. Calculation of the cons
nsumption of steam by the indicator-curve; common method. Labrousse's method. 3.–Regulation and working of compound engines.- Definitions and classification.
Continuous-expansion engine. Method of producing expansion. Effective
admission and expansion. Actual expansion ; indicator curves. Compound engine with cranks at 90°, Method of producing expansion. Curves
of volumes, and indicator-curves. Three-cylinder compound engine, with cranks at 900 and 135o. Expansion appa
ratus. Curves of volumes and indicator-curves. Adjustment of the slide-valves
according to the angle of the cranks. Advantages and disadvantages of Woolf engines. Calculation of the effective
horse-power of Woolf engines by means of indicator curves. Actual mean effort;
fictitious mean effort. Calculation of the consumption of steam. 4.-Efficiency of engines.-Analysis of indicator-curves under various conditions.
Reduction of pressure between the boiler and the cylinder, and between the cyl. inder and the condenser. Contracted passages and their employment with wet steam. Undulations of curves. Leakage past the slide-valve. Leakage past the piston. Insufficient steam-lead. Working with low pressure and late cutoff. Working at low pressure with early cut-off. Three-ported slide-valve, with valve-stem too short. Angular advance of eccentric too great and valvestem two long. Length of indicator-cord badly adjusted. Determination of average horse-power and speed at trials of engines. Relation
between the speed of the ship, the indicated power of the pistons, and the slip of the propelling instrument. Coefficient of speed. Consumption of coal per indicated horse-power per hour. Consumption of coal per square meter of gratesurface per hour. Efficiency of combustible. Loss of heat in engines.
Manipulation peculiar to each of the principal types of engines in actual use, including boat
engines. 1.-Maneuvers.- Preparations for starting. Heating the engine; blowing through
and turning over. Starting; stopping; backing. Regulating the speed ; in
creasing and moderating speed. 2.-Care of the engine while in use. -Cylinders, slide-valves, and distribution of steam.
Condensation. Movement of the machinery. Feedl-pumps and bilge-pumps. 3-Accidents to the engine.—Heating of bearings. Dangerous pounding. Leaks.
Heating of the condenser. Filling up of the condenser. Air-leaks. Leaks in
the condenser-tube packing. 4.-Management of boat engines.