## Description of Richards' improved steam-engine indicator |

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Description of Richards' improved Steam-Engine Indicator; with directions ... Volledige weergave - 1869 |

Description of Richards' improved Steam-Engine Indicator; with directions ... Volledige weergave - 1869 |

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acceleration action amount angle angular vibration ascertain atmo atmospheric line boiler centrifugal force CM CM commencement compression condensing engines connecting-rod cord counter-pressure crank cubic cubic foot cylinder degree density diagram Diameter Area direction distance employed equal expansion curve Fahrenheit fall of pressure feet per minute friction give high speeds horse-powers imparted inches of mercury increase Indicator Indicator diagram instrument Joule latent heat latter length line of perfect lines drawn mean pressure measured mercury metal moving multiplied nearly non-condensing engines number of revolutions obtained paper pencil perfect vacuum planimeter point of cut-off point of release port pounds power exerted pressure of steam re-evaporation reciprocating represent resistance return stroke revolutions per minute scale screw shown speed of piston spring square inch steam-line supposed Table taken temperature total heat units of heat varies velocity versed sine volume weight

### Populaire passages

Pagina 23 - This is owing to the difference in the speed of the piston at the opposite ends of the cylinder, which is, at the outer end of a direct-acting engine, from 35 per cent to 66 per cent greater than at the crank end, the difference varying according to the degree of angular vibration of the connecting-rod. In side-lever or beam-engines, these proportions are reversed, and the speed of the piston is greater at the upper end of the cylinder. Often also there is a difference in the lengths of the thoroughfares,...

Pagina 28 - ... To fix the Paper. — Take the outer cylinder off from the instrument, secure the lower edge of the paper, near the corner, by one spring, then bend the paper round .the cylinder, and insert the other corner between the springs. The paper should be long enough to let each end project at least half an inch between the springs. Take the two projecting ends with the thumb and finger, and draw the paper down, taking care that it lies quite smooth and tight, and that the corners come fairly together,...

Pagina 10 - The diagram thus described shows on inspection the following particulars, viz. : what proportion of the boiler-pressure is obtained in the cylinder — how early in the stroke the highest pressure is reached — how well it is maintained — at what point, and at what pressure, the steam is cut off — whether it is cut off sharply, or in what degree it is wire-drawn — at what point, and at what pressure, it is released — in a non-condensing engine, whether it is freely discharged, or what proportion...

Pagina 56 - Table the logarithm of the number nearest to the quotient, and to this add 1 ; the sum is the ratio of the gain. Then find the terminal pressure, by dividing the initial pressure by the proportion of the stroke during which the steam is admitted, and multiply it by the logarithm + 1 found as above ; the product will be the mean pressure through the stroke. EXAMPLE.

Pagina 38 - ... pressure will come a little above the atmospheric line, but it is more convenient, and answers all the purposes of the diagram better, to measure each way from the latter. The space above the steam line and between this and the line of boiler pressure shows how much the pressure is reduced in the cylinder by throttling, or by the insufficient area of the ports, proper allowance being made for the difference of pressure necessary to give the required motion to the steam in the pipe ; whilst the...

Pagina 28 - ... one to fix the paper very readily. The marking-point should be fine and smooth, so as to draw a fine line, but not cut the paper. It may be made of a brass wire ; the best material is gun-metal, which keeps sharp for a long time, and the line made by it is very durable. Lines drawn by German silver points are liable to fade. A large-sized common pin, a little blunted, answers for a marking-point very well indeed ; a small file and bit of emery cloth used occasionally will keep the point in order.

Pagina 27 - ... way of obtaining the required motion is to use a kind of weigh shaft, supported in two bearings, and placed exactly over the cross-head and fitted with two arms, one longer than the other, the long arm being connected by the cord to the cross-head, and the short arm to the indicator. The short arm must be keyed in such a position that when the piston is in the • middle of its stroke it will stand at right angles with the direction of the cord. The direction of the cord may form any necessary...

Pagina 28 - ... length, and taken up from time to time, as it may become stretched by use. On high-speed engines, it is as well, instead of using this, to adjust the cord and take up the stretching, as it takes place, by tying knots in the cord. If the cord becomes wet and shrinks, the knots may need to be untied, but this rarely happens. The length of the diagram drawn at high speeds should not exceed four and...

Pagina 38 - What is known as the Admiralty rule for the nominal horse power of engines is (1st), Multiply seven times the area of the cylinder in inches by the mean velocity of the piston in feet per minute, and divide the product by 33,000. (2nd), Square the diameter of the cylinder in inches, and multiply by the mean velocity of the piston in feet ner minute, and divide the product by 6,000.

Pagina 32 - ... the former being applied to the size of engines, irrespective of the pressure or speed employed, and the latter to the power which they exert. The term " nominal horse-power " has, moreover, acquired a variety of significations in different localities, and it has become difficult to tell, in any case, precisely what is meant by it ; but fortunately, we shall have no occasion to make any further reference to it, as it is entirely a commercial expression.