Kylchap
Encyclopedia
The Kylchap steam locomotive
steam locomotive exhaust system
was designed and patented by the famous French
steam engineer André Chapelon
, using a second-stage nozzle designed by the Finnish
engineer Kyösti Kylälä
and known as the Kylälä spreader; thus the name KylChap for this design.
The Kylchap exhaust consists of four stacked nozzles, the first exhaust nozzle (UK: blastpipe
) blowing exhaust steam
only and known as the primary nozzle, this being a Chapelon design using four triangular jets. This exhausts into the second stage, the Kylälä spreader, which mixes the exhaust steam with some of the smokebox
gases; this then exhausts into a third stage, designed by Chapelon, that mixes the resulting steam/smokebox gases mixture with yet more smokebox gases. The four nozzles of this then exhaust into the fourth stage, the classic chimney
(U.S.: stack) bell-mouth.
It was Chapelon's theory that such a multi-stage mixing and suction arrangement would be more efficient than the single stage arrangement hitherto popular in steam locomotive draughting, in which an exhaust nozzle simply is fired up the middle of the stack bell-mouth. It would also ensure a more even flow through all the firetube
s, rather than concentrating the suction on one area.
The efficiency of the Kylchap system relied on careful proportioning of its components, and perfect alignment and concentricity.
Chapelon developed the Kylchap exhaust in 1926 when it was tested on compound Pacifics of the 4500 and 3500 classes and a simple expansion Pacific of the 3591 class, producing significant improvements in steaming and in one case a 41% reduction in back-pressure. However, it first came into prominence in 1929 when applied to compound Pacific No 3566 which combined enlarged steam circuits, increased superheat, feedwater heater, thermic syphon, Lenz poppet valves with double Kylchap exhaust extractors and chimneys. On test in November 1929, the locomotive's indicated power output was found to have increased by over 60%, from 1850 ihp to 3000 ihp while its fuel and water consumption had improved by 25% compared to unrebuilt engines of the same class. These results made Chapelon's name and 3566 became famous both within France and in most countries of the Western world.
Kylchap exhausts are found on many French locomotives and also on a number of British ones. Sir Nigel Gresley
of the LNER
became a proponent when he incorporated double Kylchap exhausts into four of his A4 Pacifics, including the world speed record holder Mallard
. Arthur Peppercorn
's post-war LNER Pacifics also incorporated them, including preserved A2
532 Blue Peter, and the recreated A1 Tornado
has one. The last steam express passenger locomotive built in Britain, Duke of Gloucester, was not fitted with a Kylchap exhaust in service, despite plans to fit one, but one was fitted in preservation when it was realised that poor draughting was one of the biggest reasons behind its poor performance in its service days.
Kylchap exhausts were also fitted to some British-built export locomotives, primarily Garratt
s for Africa, but the only other nation to take them up in quantity was Czechoslovakia
, where all late steam locomotives used this exhaust design.
The Kylchap was not the only advanced steam locomotive exhaust: another design, the Lemaître
, had some success in France and England; noted Argentinian
engineer Livio Dante Porta
designed several, the Kylpor
, Lempor
and Lemprex
designs; and several U.S. railroads including the Norfolk & Western used a concentric nozzle known as the waffle iron exhaust.
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
steam locomotive exhaust system
Steam locomotive exhaust system
The Steam locomotive exhaust system consists of those parts of a steam locomotive which together discharge exhaust steam from the cylinders in order to increase the draught through the fire...
was designed and patented by the famous French
France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...
steam engineer André Chapelon
André Chapelon
André Chapelon was a noted French mechanical engineer and designer of advanced steam locomotives. Engineer of Ecole Centrale Paris, he was one of very few locomotive designers who brought a rigorous scientific method to their design, and he sought to apply up-to-date knowledge and theories in...
, using a second-stage nozzle designed by the Finnish
Finland
Finland , officially the Republic of Finland, is a Nordic country situated in the Fennoscandian region of Northern Europe. It is bordered by Sweden in the west, Norway in the north and Russia in the east, while Estonia lies to its south across the Gulf of Finland.Around 5.4 million people reside...
engineer Kyösti Kylälä
Kyösti Kylälä
Kyösti Kylälä was a Finnish Railroad engineer and self taught inventor, from Helsinki. In 1919 he patented in the UK an 'Improved means for increasing the draught in steam boilers, especially on locomotives.'...
and known as the Kylälä spreader; thus the name KylChap for this design.
The Kylchap exhaust consists of four stacked nozzles, the first exhaust nozzle (UK: blastpipe
Blastpipe
The blastpipe is part of the exhaust system of a steam locomotive that discharges exhaust steam from the cylinders into the smokebox beneath the chimney in order to increase the draught through the fire.- History :...
) blowing exhaust steam
Steam
Steam is the technical term for water vapor, the gaseous phase of water, which is formed when water boils. In common language it is often used to refer to the visible mist of water droplets formed as this water vapor condenses in the presence of cooler air...
only and known as the primary nozzle, this being a Chapelon design using four triangular jets. This exhausts into the second stage, the Kylälä spreader, which mixes the exhaust steam with some of the smokebox
Smokebox
A smokebox is one of the major basic parts of a Steam locomotive exhaust system. Smoke and hot gases pass from the firebox through tubes where they pass heat to the surrounding water in the boiler. The smoke then enters the smokebox, and is exhausted to the atmosphere through the chimney .To assist...
gases; this then exhausts into a third stage, designed by Chapelon, that mixes the resulting steam/smokebox gases mixture with yet more smokebox gases. The four nozzles of this then exhaust into the fourth stage, the classic chimney
Chimney (locomotive)
The chimney of a steam locomotive is a part of the exhaust system which helps in the creation of draught through the boiler and carries the exhaust steam and smoke clear of the driver's line of sight...
(U.S.: stack) bell-mouth.
It was Chapelon's theory that such a multi-stage mixing and suction arrangement would be more efficient than the single stage arrangement hitherto popular in steam locomotive draughting, in which an exhaust nozzle simply is fired up the middle of the stack bell-mouth. It would also ensure a more even flow through all the firetube
Fire-tube boiler
A fire-tube boiler is a type of boiler in which hot gases from a fire pass through one or more tubes running through a sealed container of water...
s, rather than concentrating the suction on one area.
The efficiency of the Kylchap system relied on careful proportioning of its components, and perfect alignment and concentricity.
Chapelon developed the Kylchap exhaust in 1926 when it was tested on compound Pacifics of the 4500 and 3500 classes and a simple expansion Pacific of the 3591 class, producing significant improvements in steaming and in one case a 41% reduction in back-pressure. However, it first came into prominence in 1929 when applied to compound Pacific No 3566 which combined enlarged steam circuits, increased superheat, feedwater heater, thermic syphon, Lenz poppet valves with double Kylchap exhaust extractors and chimneys. On test in November 1929, the locomotive's indicated power output was found to have increased by over 60%, from 1850 ihp to 3000 ihp while its fuel and water consumption had improved by 25% compared to unrebuilt engines of the same class. These results made Chapelon's name and 3566 became famous both within France and in most countries of the Western world.
Kylchap exhausts are found on many French locomotives and also on a number of British ones. Sir Nigel Gresley
Nigel Gresley
Sir Herbert Nigel Gresley was one of Britain's most famous steam locomotive engineers, who rose to become Chief Mechanical Engineer of the London and North Eastern Railway . He was the designer of some of the most famous steam locomotives in Britain, including the LNER Class A1 and LNER Class A4...
of the LNER
London and North Eastern Railway
The London and North Eastern Railway was the second-largest of the "Big Four" railway companies created by the Railways Act 1921 in Britain...
became a proponent when he incorporated double Kylchap exhausts into four of his A4 Pacifics, including the world speed record holder Mallard
LNER Class A4 4468 Mallard
Number 4468 Mallard is a London and North Eastern Railway Class A4 4-6-2 Pacific steam locomotive built at Doncaster, England in 1938. While in other respects a relatively typical member of its class, it is historically significant for being the holder of the official world speed record for steam...
. Arthur Peppercorn
Arthur Peppercorn
Arthur Henry Peppercorn, OBE was the last Chief Mechanical Engineer of the London and North Eastern Railway.- Career :...
's post-war LNER Pacifics also incorporated them, including preserved A2
LNER Peppercorn Class A2
The London and North Eastern Railway Peppercorn Class A2 is a class of steam locomotive designed for express passenger work by Arthur Peppercorn, the chief designer of the LNER after Edward Thompson...
532 Blue Peter, and the recreated A1 Tornado
LNER Peppercorn Class A1
The London and North Eastern Railway Peppercorn Class A1 is a type of express passenger steam locomotive. Forty-nine original Peppercorn Class A1s were built to the design of Arthur Peppercorn during the early British Railways era, but all were scrapped with the discontinuation of steam,...
has one. The last steam express passenger locomotive built in Britain, Duke of Gloucester, was not fitted with a Kylchap exhaust in service, despite plans to fit one, but one was fitted in preservation when it was realised that poor draughting was one of the biggest reasons behind its poor performance in its service days.
Kylchap exhausts were also fitted to some British-built export locomotives, primarily Garratt
Garratt
A Garratt is a type of steam locomotive that is articulated in three parts. Its boiler is mounted on the centre frame, and two steam engines are mounted on separate frames, one on each end of the boiler. Articulation permits larger locomotives to negotiate curves and lighter rails that might...
s for Africa, but the only other nation to take them up in quantity was Czechoslovakia
Czechoslovakia
Czechoslovakia or Czecho-Slovakia was a sovereign state in Central Europe which existed from October 1918, when it declared its independence from the Austro-Hungarian Empire, until 1992...
, where all late steam locomotives used this exhaust design.
The Kylchap was not the only advanced steam locomotive exhaust: another design, the Lemaître
Lemaître exhaust
The Lemaître exhaust is a type of Steam locomotive exhaust system developed by the Belgian engineer Jean Lemaître.-Construction:The Lemaître exhaust featured a blastpipe with 5 nozzles in a circular pattern exhausting up a large-diameter chimney stack, with a variable area nozzle exhausting up the...
, had some success in France and England; noted Argentinian
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...
engineer Livio Dante Porta
Livio Dante Porta
Livio Dante Porta was an Argentine steam locomotive engineer. He is particularly remembered for his innovative modifications to existing locomotive systems in order to obtain higher performance, energy efficiency and reduced pollution. He developed the Kylpor and Lempor exhaust systems...
designed several, the Kylpor
Kylpor ejector
A Kylpor ejector is a type of steam locomotive exhaust system developed by noted Argentine locomotive engineer Livio Dante Porta. In a steam locomotive, draft is produced in the firebox by exhausting the steam coming from the cylinders out the chimney...
, Lempor
Lempor ejector
The Lempor ejector is a Steam locomotive exhaust system developed by noted Argentine locomotive engineer Livio Dante Porta. In a steam locomotive, draft is produced in the firebox by exhausting the steam coming from the cylinders out of the chimney, or also by a blower. The LemPor exhaust delivers...
and Lemprex
Lemprex ejector
A Lemprex ejector is a type of Steam locomotive exhaust system developed by noted Argentinian locomotive engineer Livio Dante Porta . In a steam locomotive, draft is produced in the firebox by exhausting the steam coming from the cylinders out the chimney. The Lemprex exhaust will deliver improved...
designs; and several U.S. railroads including the Norfolk & Western used a concentric nozzle known as the waffle iron exhaust.