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Engineers and Mechanics Encyclopedia 1839: Railways: G. H. Palmer

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In September 1831, G. H. Palmer, of Manchester-street, Grays Inn Road, took out a patent for a variety of improvements appertaining to locomotion, which we shall proceed to notice. The abstract parts of the engine and boiler which he claims as being novel either in principle, or as regards their peculiar modification, are,-

First, the self-regulating blast apparatus, by which the quantity of fuel to be ignited in a given time is governed, in order to insure the generation of a volume of steam, suited precisely to all the variable speeds and powers of the engine.

Secondly, the steam calorific self-adjusting apparatus, which acts in conjunction with the blast regulator, and is so contrived as to lift the weight from the lever of the safety valve, and permit the steam to escape from the boiler should the aforesaid apparatus fail of instantly checking its evolution.

Thirdly, the self-acting safety apparatus, by which the security of the boiler is insured, should the apparatus for supplying it with water fail in its effect, so that in the event of the water in the boiler being reduced below a determined level, the process of combustion will be instantly suspended, and the boiler protected from injury.

Fourthly, making the products of combustion evolved from the furnace escape into the atmosphere below the level of the furnace bars, which will most effectually prevent the admission of atmospheric air into the furnace, excepting that portion which the blast and calorific regulating apparatus permits the blowers to project upon the fuel undergoing combustion.

Fifthly, the pipes leading from the opposite ends of the horizontal part of the boiler, are designed to convey the water (which must be distilled) most remote from the direct action of the furnace, to replace that portion which may be carried to the upper part of the boiler by the great volume of steam generated between the two concentric cylinders.

Sixthly, to insure a length of stroke in high pressure engines, and that without increasing the diameter of the piston rods beyond that which is required to withstand the alternate tug and thrust; and without resorting to the very objectionable short stroke and piston rod of so large a diameter.

Seventhly, the slide valves, with their various modifications, requiring neither casings nor stuffing-boxes, the patentee, claims as perfectly novel; the actions of these being seen, admit of mathematical adjustment, and enables the engineer instantly to reverse or stop the engine at pleasure.

Eighthly, for a modification of the crank and beam intended to supersede the use of a beam of the usual weight and dimensions, parallel motion, cross heads, and costly fittings and bearings connected therewith. This mode of converting the reciprocating into the rotative motion, the patentee says, "accomplishes the grand desideratum of making one cylinder produce a more regular and equalized motion than can be accomplished by two cylinders when used to give motion to locomotive engines or paddle wheels."

Ninthly, the condensation by which highly elastic steam of any temperature may be converted into water, without the application of injections, or by the extension of surface by making the cubic contents of the condensing chamber equal to the number of cubic inches of steam discharged.

The said condensing vessel to consist of one or more chambers, which may be made of light copper or other material. The sphere is preferred, as combining strength with great capacity. The conversion of highly elastic steam into the liquid state is to be accomplished exclusively by expansion, without regard to cooling surface. The patentee claims the making the condensing chamber of flexible substances, as varnished canvas, silk, cotton, or other suitable air and steam-tight material, so as to allow of its alternate inflation and collapsing, every stroke of the engine; and to avoid rupture (should the steam ever arrive at an elasticity exceeding the atmospheric pressure), it must be enclosed in a wove wire casing, to permit the atmospheric air to enter and escape with great facility, without checking the inflation, or collapsing of the aforesaid condensing chamber. The more this condensing chamber exceeds the proportions given, the more effectual will be its operation, as the steam will expand with less resistance than in a vessel of less capacity, as it more resembles the process of turning highly elastic steam into the atmosphere.

The form of the engine, as applied to locomotive carriages, will be explained by the following figures, and descriptive references accompanying them.

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Fig. 1 is an elevation showing the disposition of the various parts.

Fig. 2 is a longitudinal section of the boiler and furnace, showing the flues, steam, cylinder, &e.

Fig. 3 is a transverse section of the boiler, furnace, and calorific regulator, showing its connexion with the blast regulator.

Fig. 4 is a sectional plan of the lower part of the boiler, furnace, and flues.

Fig. 5 is a longitudinal section of one of the slide valves with its seat.

Fig. 6 is a plan of the seat, showing the steam and condensing passages.

The same letters of reference are used to denote the same parts in all the views. A is the boiler, in the lower part of which, and concentric with it, is placed the furnace B, secured to it by flanges, bolts, and nuts. The grate C is supported upon an iron frame D, and is retained in its place by a wedge, or other simple fastening, and by releasing which, the grate may be withdrawn when required.

The furnace is replenished with fuel through an aperture in the crown, by means of a pipe extending outside; the boiler terminates by two slides or doors, which are alternately opened when fuel is admitted; to prevent the discharge of the heated gases, a rake is added, working in a stuffing-box, to force the fuel into the furnace should the pipe get choked.

It is the intention of the patentee, however, to adopt a self-acting mode of feeding the furnace with fuel, by means of fluted rollers, or other equally efficient means, and which will receive their motion from the steam-engine. E-E-E-E are four flue pipes connected to the top of the furnace, and descending below the bottom of the ash-pit, which prevents the natural flow of atmospheric air to supply the furnace.

The exit of the pipes being carried below the level of the furnace, is adopted in preference to cocks, or such like contrivances, in conjunction with the blast-regulating apparatus. F-F are two circulating tubes, by which the annular space round the furnace is more uniformly supplied with water. G, a pipe with its valves, through which the supply of water to the boiler is injected, to replace the quantity evaporated. H the injecting pump for supplying the boiler with water I, the blowing apparatus, for injecting the requisite quantity of atmospheric air into the furnace. K, a pipe through which the atmospheric air is injected into the casing L, which surrounds the ash-pit, between which a communication is formed by perforations in the lower part of the cylinder which constitutes the furnace: the blast is by this means rendered less partial in its action on the fuel .

To one extremity of the pipe K is attached a regulating valve or cover M, which, when closed, prevents the exit of the air contained in the pipe, - the quantity of air discharged through this aperture depends on the area of the opening given to the valve. It is opened or shut, or otherwise adjusted, by means of a screw and handle, or may be operated upon by any other convenient means. This valve is used for regulating the quantity of atmospheric air passed through the furnace, suited to all the variations of resistance.

To the other extremity of the pipe K is adapted a hinged valve or cover N, so weighted as to counterpoise the pressure of the air within; the pipe, when closed, compels the air discharged by the blowing apparatus to pass into the casing L, and from thence into the furnace, through the flue-pipes E-E, &c., into the atmosphere, excepting that quantity which may be discharged through the valve M. The use of this valve is to limit the temperature of the water, and consequently the pressure of the steam in the boiler, by permitting, when open, the discharge of a great portion of the atmospheric air otherwise required for combustion. To effect this object, the valve N is connected by levers O-P-Q, with their necessary rods of communication, to the calorific regulating apparatus R, which consists of a piston of sufficient area to overcome the resistance opposed to it, working through a stuffing-box in a cylindrical syphon tube, containing a quantity of mercury as a medium by which the steam, passing from the boiler into the regulating chamber, acts upon the aforesaid piston.

S, a safety-valve, with its graduated lever and weight; a loop T is formed on the end of the lever, and embraces the screwed end of the regulator piston; when the nut V comes in contact with the loop, the lever and safety-valve are lifted effectually, preventing the occurrence of accidents, should the safety-valve remain closed beyond the limiting pressure.

The action of the safety-valve and lever is tendered simultaneous by two small connecting links. At X is a chamber attached to the crown of the furnace, and connected by a tube Y, with a piston and cylinder of precisely the same description and construction as that used for the calorific regulator R, and may be placed in any convenient situation for operating on a safety slide cock or valve Z, which, when the water in the boiler has evaporated so low as to endanger its safety from a deficiency of supply front the force-pump, is closed, and completely prevents the passage of atmospheric air into the furnace - thus combustion instantly ceases, the ignited fuel being deprived of air.

The motion communicated to the piston by the steam generated in the chamber X, operates on the levers shown, until the vertical lever rising with the piston, the detent passes the projecting fin, when the slide Z is instantaneously released, and falls by its own gravity, completely closing the passage through the pipe K. The combustion being suspended, the temperature of the water, and consequently the pressure of the steam, is instantly reduced, thus preventing the destruction of the boiler by the powerful action of the fuel when the heating surface is unprotected by the water.

For facilitating the reference, the regulators R are arranged with a view to perspicuity, rather than mechanical exactness. It will be perceived that the safety slide Z with its appendages, have been omitted in Fig. I, lest it should have been rendered too confused.

The steam cylinder, piston, and stuffing-boxes, being of the usual construction, do not require a particular description, the only peculiarity being the great length of the cylinder compared with its diameter, and the small diameter of the piston rod. The adjustment of the piston in the cylinder is effected by means of screws and nuts at the two extremities, where they are connected to the chains s-s by the loops r-r. The slide valves a-a are connected together by two adjusting side rods b-b, and have two apertures each, with a connecting chamber c. The seats have each three apertures, of equal area with those in the slide, so that the alternate operation of admitting steam to the cylinder, and condensing it, is produced without the aid of a casing or cover over the slide. The movement producing the alternating motion of the slides, is of the tappet kind, capable of the nicest adjustment, by means of screws and nuts at each end of the tappet rods d-d, which also connect them with the chains.

e is a carriage for supporting the tappet lever f, and the guide rollers g-g, against which the tappet rods rub, and by which they are prevented from deflecting out of the right line when brought into action. The side rods b are united at h, the middle of their length, by a carriage furnished with friction rollers, which is embraced by the forked ends of the tappet rods f, and by which the slides are moved. The pressure tending to lift the slides from their seats by the action of the steam in their passages, is counterbalanced by an external pressure produced by two helical springs k-k, at the back of each slide, and the friction is diminished by two grooved rollers 1-, working on a guide parallel to the face of the slide. m is the condensing chamber, into which the steam is admitted after it has performed its office in the cylinder, where it is permitted to expand freely. The slide valve seats communicate with the upper part by the pipes n-n, which enter the chamber separately, or united in one pipe.

The water produced by the condensation of the steam is drawn from the chamber by the force-pump H through the pipe and valves o, which chamber is furnished with an inverted safety-valve p to prevent collapsing. The steam is completely excluded from the engine by closing the slide valve q. The chains s-s are fixed to the pulleys t-t, whose axes turn in bearings on the bracket v-v, firmly secured to the transverse bearers of the frame work of the carriage. These pulley's should be more in circumference than double the length of the piston's stroke.

The reciprocating motion of the pulley t and the engine, produce the revolution or rotation of the crank shaft W, by means of a lever keyed on one end of the pulley axis, and the intervention of the connected rod y, the crank shaft revolving in bearings attached to the frame of the carriage. The radius of the lever must exceed in a trifling degree that of the crank to w-w. z, a toothed spur-wheel working into a pillion of half its diameter on the axis of the carriage-wheels 5, so that the carriage performs a distance equal to twice the circumference of the wheels 5 for each double stroke of the engine. Any other proportions of the wheel and pinion may of course be adopted as the nature of the machine or the required speed of the carriage may render necessary.

On the crank shaft W is a pulley 6 grooved, to receive a catgut band for the purpose of driving the machinery to work the blowing apparatus. These wheels 3 and pulley 6 have been represented by dotted lines to prevent confusion.

The machinery for working the blowing apparatus consists of two pulleys 7 on an axis 8, supported on two brackets 9 fixed to the side frames of the carriage; one pulley to receive the motion from the crank shaft W, and the other to communicate the motion to the pulley 10. On the axis of the blowing fan a greater number of pulleys may be found convenient to vary the velocity of the blowing fan, according to circumstances. The pulley axis 8 is cranked, to form a winch by which the blowing apparatus can be worked by manual labour, where the engine is at rest, and for which purpose a provision is made to disengage the pulley from the crank shaft W, by sliding the brass bearings in the bracket heads in the direction of the crank shaft. The catgut band will then be slackened, and the pulley will revolve without it; when it is required to be connected with the engine, the reverse of this operation will be necessary, in either of which positions, the axis will be retained by a set screw 11. The force pump is worked by means of an adjusting crank 12, keyed on one end of the axis of the pulley t, and communicating with the pump piston by a connecting rod and slings 13. The pump is secured to a portion of the bracket v, projecting below the carriage frame.

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