page_title: Vertical boiler with horizontal fire-tubes
section_title: Cochran boiler
hierarchical_section_title: Vertical boiler with horizontal fire-tubes / Parallel tube boilers / Cochran boiler
caption_attribution_description: English: Identifier: railwaylocomotiv19newy (find matches) Title: Railway and locomotive engineering&#160;: a practical journal of railway motive power and rolling stock Year: 1901 (1900s) Authors: Subjects: Railroads Locomotives Publisher: New York&#160;: A. Sinclair Co Contributing Library: Carnegie Library of Pittsburgh Digitizing Sponsor: Lyrasis Members and Sloan Foundation View Book Page: Book Viewer About This Book: Catalog Entry View All Images: All Images From Book Click here to view book online to see this illustration in context in a browseable online version of this book. Text Appearing Before Image: air of a commander.As you tread your wondering way youmarvel at the multitude of men thateddy and drift like great throngs in acity holiday. On the mighty engines,that seem to blossom into being beforeyour bewildered eyes, the men clusterlike bees. It seems impossible thatthere could be order in all this apparentdisorder, and yet the ponderous ma-chines grow as you look at them. Asquad of men underneath are tighten-ing up the big binders and braces andbrake hangers. Others are at the rock-ers and tumbling shaft blocks. Thespring hangers and equalizers engagethe attention of more. The shiningguides and crossheads are rising intoplace. There are hands setting thecylinder cocks, and keen eyes gleamfrom between the spokes of enameledwheels. There are air hammers rattlinga double tattoo around the smoke box,and others are doing a duet on the de-flector sheet inside. Pipe fitters areperched on the running board braces,and polished pipes are bending andtwisting into fantastic shapes like the Text Appearing After Image: COCHRANS STEAM MOTOR, GREAT NORTH OF SCOTLAND RAILWAY. lowed thunders of Niagara, An armyof more than ten thousand men are atwork. In the sumptuously fitted officesthere is an elegant air of comfortpeculiar to well-managed and prosper-ous institutions. The colored man whotakes your card has the courtesy of a tentacles of a galvanized octopus. Over-head, cranes are passing, and danglinghooks are swinging the dome casinginto place. On the ground, ten feetaw-aj-, from a white pyramid of asbestosblocks, a man is throwing pieces in theair, like pitching sheaves to a high stack 64 RAILWAY AND LOCOMOTIVE ENGINEERING February, igo6. ir. harvest time, and another is catchingthem in midair and placing them inposition around the lofty boiler shell.The dust is falling in showers from theflying pieces, and the shafts of brokensunshine that stream in fragments fromthe far roof gild the silvery showerinto a golden cloud. Inside the loftyengine cab the burnished brasswork issparkling into place, and Note About Images Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original work.
context_page_description: A vertical boiler with horizontal fire-tubes is a type of small vertical boiler, used to generate steam for small machinery. It is characterised by having many narrow fire-tubes, running horizontally.
  Boilers like this have been widely used on ships as either auxiliary or donkey boilers. Smaller examples, particularly the Robertson type have been used for steam wagons.
context_section_description: The Cochran boiler was produced by Cochran & Co. of Annan, Scotland. It is widely used in marine practice, either fired directly by coal or oil fuels, or else used for heat recovery from the exhaust of large diesel engines. Where such a boiler may be heated either by the exhaust gases of the main propulsion plant, or else separately fired when in port (usually by oil rather than coal) it is referred to as a composite boiler.
  The boiler is a cylindrical vertical water drum with a hemispherical domed top. This domed shape is strong enough not to require staying. The firebox is another hemispherical dome, riveted to the base foundation ring to give a narrow waterspace.
  The fire-tubes are arranged in a single horizontal group above this, mounted between two flat vertical plates that are inset into the boiler barrel. The first of these plates forms a shallow combustion chamber and is connected to the firebox by a short diagonal neck. The combustion chamber is of the "dry back" form and is closed by a steel and firebrick plate, rather than a water jacket. The exhaust from the fire-tubes is into an external smokebox and a vertical flue. For maintenance access to the tubes, a manhole is provided in the hemispherical dome.
  A typical Cochran boiler, as illustrated, might be 15 feet (4.57 m) high and 7 feet (2.13 m) in diameter, giving a heating surface of 500 square feet (46.45 m²), and a grate area of 24 square feet (2.23 m²). Working pressure is between 100 and 125 psi (6.9 and 8.6 bar; 690 and 860 kPa).
  Where composite firing is used, there are several possible arrangements for the heating gases. Most use a double-pass tube arrangement where another dry back combustion chamber routes the gases from one tube bank to return through the other. Some arrangements use a separate tube bank for the heat recovery exhaust gases or the direct firing gases, others pass the exhaust gases into the top of the (unlit) firebox. A pure heat-recovery boiler may have no firebox at all, other than a shallow domed plate for strength.
  Cochran also offer a modified "Sinuflo" fire-tube, which is claimed to offer better heat transfer from the gases. This is bent into a number of horizontal sinusoidal waves, rather than being straight.
  The Cochran boiler was not applied to locomotives, but was used for a pair of experimental steam railmotors built for the GNSR by Andrew Barclay in 1905. These were not successful and were scrapped after a few years, although one coach body survives in a poor state.
caption: GNSR railmotor
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