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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />  <title>Why not use 3 cylinders to improve balancing? | 5AT Advanced Steam Locomotive Project</title>   <link href="layout.css" rel="stylesheet" type="text/css" />  <base href="http://5at.co.uk/" /> <script type="text/javascript"> var gaJsHost = (("https:" == document.location.protocol) ? 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align="right"><a href="index.php"><img src="images/5AT_logo.jpg" alt="5AT" width="268" height="72" border="0" /></a></div></td> <td width="100"> </td> <td><div id="trainwide"><img src="images/train-wide.jpg" alt="5at Train" width="401" height="72" /></div></td> </tr> <tr> <td colspan="3" ><div class="titlebar" id="headertitle"> The 5AT Group - Steaming Ahead with Advanced Technology Enhancing Performance -- Improving Reliability -- Reducing Costs -- Controlling Emissions </div></td> </tr> </table></td> </tr> <tr> <td ><div class="menubar"><div id="menuwrapper"> <ul id="primary-nav"> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/"> - Home -</a> <ul class="unli"> <li> <a href="http://5at.co.uk/">Home</a> </li> <li> <a href="http://5at.co.uk/index.php/home/Project-Suspension-Announcement.html">Project Suspension Announcement</a> </li> <li> <a href="http://5at.co.uk/index.php/home/news-detail.html">News</a> </li> <li> <a 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<a href="http://5at.co.uk/index.php/the-5at-group-2/planning-team/richard-coleby.html">Richard Coleby</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/planning-team/jamie-keyte.html">Jamie Keyte</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/planning-team/iain-jack.html">Iain Jack</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/planning-team/Chris-Newman.html">Chris Newman</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/planning-team/robin-barnes.html">Robin Barnes</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/planning-team/alan-fozard.html">Alan Fozard</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements.html">Acknowledgements</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/david-smith.html">David Smith</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/brian-mccammon.html">Brian McCammon</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/malcolm-cluett.html">Malcolm Cluett</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/Allan-Wallace.html">Allan Wallace</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/david-pawson.html">David Pawson</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/bob-bramson-2.html">Bob Bramson</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/david-ward.html">David Ward</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/martyn-bane.html">Martyn Bane</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/paul-catchpole.html">Paul Catchpole</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/terry-flynn.html">Terry Flynn</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/dominic-wells.html">Dominic Wells</a> </li></ul></li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/definitions/terrms-and-definitions.html">Technical Terms -</a> <ul class="unli"> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/definitions/terrms-and-definitions.html">Steam Loco Definitions</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/Locomotive-Thermal-Efficiency.html">Thermal Efficiency</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/locomotive-power.html">Power and Indicator Diagrams</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/power-to-weight-ratio-2.html">Power-to-Weight Ratio</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/grate-limit.html#equivevap">Equivalent Evaporation</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/specific-steam-consumption.html">Specific Steam Consumption</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/grate-limit.html">Grate Limit and Boiler Efficiency</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/front-end-limit-2.html">Front-End Limit</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/tractive-effort.html">Tractive Effort</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/adhesion-2.html">Adhesion</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/resistance.html">Resistance</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/simple-compound.html">Simple/Compound</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/motion.html">Motion</a> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/valve-gear.html">Valves, Valve Gear etc</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/valve-gear/reuleaux-diagram.html">Reuleaux Diagram</a> </li></ul> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/snifting-and-bypass-valves.html">Snifting, Drifting, Bypass and Herdner Valves</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/hammer-blow-2.html">Balancing & Hammer Blow</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/combustion-air.html">Combustion Air</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/superheating.html">Superheating</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/steam-chest.html">Steam Chest</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/clearance-volume.html">Clearance Volume</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/condensation.html">Condensation/Wall Effects</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/triangular-losses.html">Triangular Losses</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/incomplete-expansion.html">Incomplete Expansion</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/exhaust-systems-2.html">Exhausts</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/terrms-and-definitions/brakes.html">Brakes</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/definitions/thermodynamics.html">Thermodynamics</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/definitions/thermodynamics/thermodynamic-equations.html">Thermodynamic Equations</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/thermodynamics/thermodynamic-definitions.html">Thermodynamic Definitions</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/thermodynamics/enthalpy.html">Enthalpy</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/thermodynamics/entropy.html">Entropy</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/thermodynamics/mollier-h-s-diagram.html">Mollier Diagrams </a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/thermodynamics/steam-tables.html">Steam Tables</a> </li> <li> <a href="http://5at.co.uk/index.php/definitions/thermodynamics/anomalies.html">Thermodynamic Anomalies</a> </li></ul></li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/modern-steam-2/modern-steam.html">Modern Steam -</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modern-steam.html">Introduction</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/andre-chapelon.html">Andr茅 Chapelon</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/ingeniero-livio-dante-porta.html">Livio Dante Porta</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/phil-girdlestone.html">Phil Girdlestone</a> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/modern-steam-2/steam-specialists.html">Present Day Steam Specialists</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/steam-specialists/david-wardale.html">David Wardale</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/steam-specialists/roger-waller.html">Roger Waller</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/steam-specialists/shaun-mcmahon.html">Shaun McMahon</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/steam-specialists/nigel-day.html">Nigel Day</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/steam-specialists/ian-gaylor.html">Ian Gaylor</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/steam-specialists/manuel-ramos.html">Manuel Ramos: </a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/steam-specialists/ian-screeton.html">Ian Screeton</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam.html">Principles of Modern Steam</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/second-generation-steam.html">"Second Generation Steam"</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/gpcs.html">Gas Producer Combustion System (GPCS)</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/combustion-air-preheating.html">Combustion Air Preheating</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/porta-s-water-treatment.html">Porta's Water Treatment</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/feedwater-heating-4.html">Feedwater Heating</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/steam-press-temp.html">Steam Press & Temp</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/low-heat-losses.html">Low Heat Losses</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/steam-tightness.html">Steam Tightness</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/long-strokes-and-high-rotation-rates.html">Long Strokes and High Rotation Rates</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/Lubrication-and-Tribology.html">Lubrication and Tribology</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/enhanced-valve-events.html">Enhanced Valve Events</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/internal-streamlining.html">Internal Streamlining</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/valve-design.html">Piston Valve Design</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/piston-valve-rod-packing.html">Piston & Valve Rod Packing </a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/compound-expansion.html">Compound Expansion</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/the-coefficient.html">The 伪 Coefficient</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/exhausts.html">Exhaust Systems</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/kordina.html">Kordina</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/advanced-adhesion.html">Advanced Adhesion</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/drifting-techniques.html">Drifting Techniques</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/engine-tender-buffering.html">Engine-Tender Buffering</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/principles-of-modern-steam/franklin-wedges.html">Franklin Wedges</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/modern-steam-2/modernising-options-1.html">Modernising Options</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modernising-options-1.html">Modernising Options</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modernising-options-1/modernising-applications.html">Modernising Applications</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modernising-options-1/boosting-loco-performance.html">Boosting Loco Performance</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modernising-options-1/improving-fuel-use-and-carbon-emissions.html">Reducing Fuel Consumption and Carbon Emissions</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modernising-options-1/reducing-maintenance-costs.html">Reducing Maintenance Costs</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modernising-options-1/costs-improving-reliability.html">Improving Reliability</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany.html">Modern Steam Miscellany</a> <ul class="unli"> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany/the-red-devil.html">The Red Devil</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/references/broadcasts/audio-recordings.html">Red Devil Audio Recordings</a> </li></ul> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany/sar-class-19d-no-2644-2.html">SAR Class 19D No 2644</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany/rfirt.html">Rio Turbio Railway</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany/porta-s-locomotive-no-1802.html">Porta's Locomotive No 1802</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany/dlm-52-8055.html">DLM 52-8055</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany/dlm-rack-tanks.html">DLM Rack Tanks</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany/ss-montreux.html">SS Montreux</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany/fcaf-garratt-no-2.html">FCAF Garratt No 2</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany/kirklees-light-railway.html">Kirklees Light Railway</a> </li> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/modern-steam-miscellany/bure-valley-railway.html">Bure Valley Railway</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/modern-steam-2/contributions.html">Reades' Contributions</a> <ul class="unli"> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/modern-steam-2/contributions/brian-gregson.html">Brian Gregson</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/modern-steam-2/contributions/brian-gregson/water-tube-boilers.html">Water Tube Boilers</a> </li></ul></li></ul></li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/engineering/engineering-design.html">Engineering -</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/engineering/engineering-design.html">Introduction</a> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/engineering/fundamental-design.html">Fundamental Design </a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/engineering/fundamental-design/5at-calculations.html">5AT FDCs</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/fundamental-design/notes-on-fdc-1.html">Notes on FDC 1</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/fundamental-design/notes-on-fdc-1-4.html">Notes on FDC 4</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/fundamental-design/notes-on-fdc-8.html">Notes on FDC 8</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/fundamental-design/notes-on-fdc-9.html">Notes on FDC 9</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/fundamental-design/notes-on-fdc-11.html">Notes on FDC 11</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/fundamental-design/notes-on-fdc-12.html">Notes on FDC 12</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/fundamental-design/notes-on-fdc-13.html">Notes on FDC 13</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/fundamental-design/notes-on-fdc-18.html">Notes on FDC 18</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/fundamental-design/wardale-s-summary.html">Wardale's Summary</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/engineering/detail-design.html">Detail Design</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/engineering/detail-design/engineering-help.html">Engineering Help</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/detail-design/scale-of-thetask.html">Scale of theTask</a> </li></ul> </li> <li> <a href="http://5at.co.uk/index.php/engineering/drawings.html">Drawings</a> </li> <li> <a href="http://5at.co.uk/index.php/engineering/research-opportunities.html">Research Opportunities</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/the-locomotive/project-summary.html">- The 5AT Project -</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/the-locomotive/project-summary.html">5AT Project Summary</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/project-aims.html">5AT Project Aims</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/the-5at-locomotive.html">The 5AT - Introduction</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/design-philosophy.html">Design Philosophy</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-specifications.html">5AT Specifications</a> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/the-locomotive/5at-performance.html">5AT Performance</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-performance/calculated-performance.html">Calculated Performance</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-performance/computer-simulation.html">Computer-Simulation</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-performance/performance-examples.html">Performance Examples </a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/the-locomotive/5at-features.html">5AT Features </a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/thermal-efficiency-2.html">Thermal Efficiency</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/power-to-weight-ratio.html">Power-to-Weight Ratio</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/adhesion.html">Adhesion & Sanding</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/reliability-2.html">Reliability</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/operating-costs.html">Operating Costs</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/maintenance-costs.html">Maintenance Costs</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/route-availability.html">Route Availability</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/fuel-consumption.html">Fuel Consumption</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/operating-range.html">Operating Range</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/valves-and-steamchest.html">Valves and Steamchest</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-features/feedwater-heating-3.html">Feedwater Heating</a> </li></ul> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/5at-vs-5mt.html">5AT vs. 5MT</a> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/the-locomotive/emissions-and-environment.html">5AT and the Environment</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/the-locomotive/emissions-and-environment/emissions.html">Emissions</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/emissions-and-environment/emissions-environment.html">Fuels</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/the-locomotive/options/alternative-strategies.html">5AT Options</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/the-locomotive/options/alternative-strategies.html">Optional Strategies</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/options/8at-2-8-0.html">8AT 2-8-0</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/options/8att-2-8-4t.html">8ATT 2-8-4T</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/options/longer-term-options.html">Longer Term Options</a> </li></ul> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/feasibility-study-3.html">5AT Feasibility Study</a> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/the-locomotive/promotion/project-promotion.html">Promotion</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/the-locomotive/promotion/project-promotion.html">Promoting the 5AT</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/promotion/presentations.html">Presentations</a> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/the-locomotive/promotion/published-articles-and-letters-2.html">Published Articles and Letters</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/the-locomotive/promotion/published-articles-and-letters-2/1998-9.html">1998 - 2001</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/promotion/published-articles-and-letters-2/2002---2005.html">2002 - present</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/promotion/published-articles-and-letters-2/overseas-articles.html">Overseas Articles</a> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/promotion/published-articles-and-letters-2/non-railway-press.html">Non Railway Press</a> </li></ul> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/promotion/5AT-art-work.html">Art Work</a> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/the-locomotive/promotion/5AT-models.html">5AT Models</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/the-locomotive/promotion/5AT-models/laura-s-5at-animation.html">Laura's 5AT Animation</a> </li></ul> </li> <li> <a href="http://5at.co.uk/index.php/the-locomotive/promotion/liveries.html">Livery Options</a> </li></ul></li></ul> </li> <li class="menuactive menuparent"> <a class="menuactive menuparent" href="http://5at.co.uk/index.php/faqs-2/faqs.html">- FAQs -</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/faqs-2/faqs.html">FAQ Summary</a> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/faqs-2/general-questions.html">General Questions</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/faqs-2/general-questions/more-innovation.html">More Innovation? </a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/general-questions/cutting-metal.html">Cutting Metal</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/general-questions/loco-turning.html">Loco turning?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/general-questions/why-a-4-6-0.html">Why a 4-6-0?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/general-questions/why-not-a-4-8-0.html">Why not a 4-8-0 ?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/general-questions/larger-driving-wheels.html">Larger driving wheels?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/general-questions/200-km-h-speed-approval.html">200 km/h Speed Approval</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/general-questions/network-rail-approvals.html">Network Rail Approvals?</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/faqs-2/performance-questions.html">Performance Questions</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/faqs-2/performance-questions/5at-performance-exaggerated.html">5AT performance exaggerated?:</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/performance-questions/reliability.html">Reliability </a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/performance-questions/thermal-efficiency.html">Thermal Efficiency</a> </li></ul> </li> <li class="menuactive menuparent"> <a class="menuactive menuparent" href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions.html">Motion, Balancing, Valve Gear</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/why-walschaerts-valve-gear.html">Why Walschaerts valve gear ?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/why-not-baker-valve-gear.html">Why not Baker Valve Gear?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/why-not-british-caprotti.html">Why not British Caprotti?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/variable-lead-valve-gear.html">Why not Variable Lead?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/piston-vs-caprotti-valves.html">Piston vs. Caprotti Valves</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/piston-speed-too-high.html">Piston speed too high?</a> </li> <li class="menuactive"> <a class="menuactive" href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/why-not-3-cylinders.html">Why not 3 cylinders? </a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/hammer-blow.html">Hammer Blow?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/why-tail-rods-not-used.html">Why Piston Tail Rods not used?</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/faqs-2/boiler-questions.html">Boiler Questions</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/faqs-2/boiler-questions/boiler-large-enough.html">Boiler large enough?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/boiler-questions/boiler-pressure-too-high.html">Boiler pressure too high?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/boiler-questions/FAQ-9a.html">Why not higher pressure? </a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/boiler-questions/feedwater-heating.html">Feedwater Heating</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/faqs-2/steam-flow-and-exhaust.html">Steam Flow and Exhaust</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/faqs-2/steam-flow-and-exhaust/why-not-a-compound.html">Why not a compound?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/steam-flow-and-exhaust/steam-pipes.html">Steam Pipes</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/steam-flow-and-exhaust/exhaust-systems.html">Exhaust Systems</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/steam-flow-and-exhaust/steam-jacket-to-cylinders.html">Steam Jacket to Cylinders?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/steam-flow-and-exhaust/use-of-exhaust-lap.html">Use of Exhaust Lap</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/steam-flow-and-exhaust/Wardale-Koopmans-Correspondence.html">Wardale - Koopmans Correspondence </a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/faqs-2/fuel-questions.html">Fuel Questions</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/faqs-2/fuel-questions/what-is-gas-oil.html">What is "Gas Oil"?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/fuel-questions/why-not-coal-fuel.html">Why not Coal Fuel? </a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/fuel-questions/what-about-bio-mass-fuel.html">What about Bio-Mass Fuel?</a> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/fuel-questions/excess-combustion-air.html">Excess Combustion Air </a> </li></ul> </li> <li> <a href="http://5at.co.uk/index.php/faqs-2/questions-about-tech-specification.html">Technical Specs</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/references/references-and-links.html">- References -</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/references/references-and-links.html">References - General</a> </li> <li> <a href="http://5at.co.uk/index.php/references/porta-s-papers.html">Porta's Papers</a> </li> <li> <a href="http://5at.co.uk/index.php/references/wardale-letters.html">Wardale Letters</a> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/references/simulation-software.html">Simulation Software</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/references/simulation-software/software.html">Prof. Bill Hall's Software</a> </li> <li> <a href="http://5at.co.uk/index.php/references/simulation-software/steam-locomotive-simulator.html">"STEAM" Locomotive Simulator</a> </li> <li> <a href="http://5at.co.uk/index.php/the-5at-group-2/acknowledgements/Allan-Wallace.html">Allan Wallace's Software</a> </li></ul> </li> <li class="menuparent"> <a class="menuparent" href="http://5at.co.uk/index.php/references/printed-reference-material.html">Books and Publications</a> <ul class="unli"> <li> <a href="http://5at.co.uk/index.php/references/printed-reference-material/the-5at-fdcs.html">The 5AT FDCs</a> </li> <li> <a href="http://5at.co.uk/index.php/references/printed-reference-material/red-devil-book.html">Red Devil Book - a Review</a> </li> <li> <a href="http://5at.co.uk/index.php/references/printed-reference-material/advanced-steam-locomotive-development.html">Advanced Steam Loco Development</a> </li> <li> <a href="http://5at.co.uk/index.php/references/printed-reference-material/la-locomotive-a-vapeur.html">La Locomotive a Vapeur</a> </li> <li> <a href="http://5at.co.uk/index.php/references/printed-reference-material/chapelon---by-col-rogers.html">Chapelon - by Col. 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vertical-align:top"> <table width="100%" border="0" cellspacing="0" cellpadding="0"> <tr> <td colspan="3" style='text-align:left'><div align="right"><form id="cntnt01moduleform_1" method="get" action="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/why-not-3-cylinders.html"> <div class="hidden"> <input type="hidden" name="mact" value="Search,cntnt01,dosearch,0" /> <input type="hidden" name="cntnt01returnid" value="88" /> </div> <label for="cntnt01searchinput">Search: </label><input type="text" class="search-input" id="cntnt01searchinput" name="cntnt01searchinput" size="20" maxlength="50" value="Enter Search..." onfocus="if(this.value==this.defaultValue) this.value='';" onblur="if(this.value=='') this.value=this.defaultValue;"/><input class="search-button" name="submit" value="Submit" type="submit" /> </form> </div></td> </tr> <tr> <td colspan="3" style='text-align:left'><div class="breadcrumbs"> You are here: <a href="http://5at.co.uk/"> - Home -</a> » <a href="http://5at.co.uk/index.php/faqs-2/faqs.html">- FAQs -</a> » <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions.html">Motion, Balancing, Valve Gear</a> » Why not 3 cylinders? </div></td> </tr> <tr> <td colspan="3"><h2>Why not use 3 cylinders to improve balancing? </h2> <hr/></td> </tr> <tr> <td colspan="3" style=''><div id="content">The following answer is taken from Wardale's response to an <a href="http://5at.co.uk/index.php/references/miscellaneous-articles-and-letters/2002-articles-and-letters/2002-attewell-letter.html" title="Unpublished Letter from Bryan Attewell to Steam Railway" >unpublished letter from Bryan Attewell</a> written in response to Wardale's two-part article "<a href="index.php/references/miscellaneous-articles-and-letters/2002-articles-and-letters/2002-article---steaming-into-the-future.html">Steaming into the Future</a>" published in Steam Railway magazines #272 and #273: "Mr Attewell criticises the choice of 2 cylinders for high speed, but the 2-cylinder locomotive cannot be simply condemned without fully exploring its possibilities. The acceptability of a 2-cylinder engine hinges on the issue of balancing, as I have acknowledged in my article. Although Mr. Attewell invokes Newton's laws to support his case, it is in fact these same laws which show us how a 2-cylinder engine can be made acceptable. Newton tells us that force = mass x acceleration, so (i) the reciprocating masses cause forces and (ii) these forces act on a mass (the locomotive) to produce accelerations (i.e. vibrations). Considering item (i), force is proportional to the mass of the reciprocating parts, which in the BR 5MT are far from being as light as they should be (notwithstanding the LNER type crosshead, a design which is not amenable to lighter construction by using aluminium). A reasonable yardstick is the mass of the reciprocating parts per ton of piston thrust, so let us consider the following: <table style="text-align: center; width: 671px; height: 113px;" border="1" cellspacing="0" cellpadding="0" align="center"> <tbody style="text-align: center;"> <tr style="text-align: center;"> <td style="text-align: center;" width="28%" height="44">聽</td> <td style="text-align: center;" width="18%">Piston thrust, (metric) tons</td> <td style="text-align: center;" width="21%">Mass of reciprocating parts per cylinder, lb.</td> <td style="text-align: center;" width="33%">Mass of reciprocating parts in lb. per ton of piston thrust</td> </tr> <tr style="text-align: center;"> <td style="text-align: center;" height="24">BR 5MT</td> <td style="text-align: center;">28.9</td> <td style="text-align: center;">826</td> <td style="text-align: center;">28.6</td> </tr> <tr style="text-align: center;"> <td style="text-align: center;" height="42">Burlington RR 4-6-4 with Timken lightweight parts</td> <td style="text-align: center;">55.7</td> <td style="text-align: center;">944</td> <td style="text-align: center;"> <div style="text-align: center;">16.9</div> </td> </tr> </tbody> </table> This illustrates the extent to which the reciprocating parts can be lightened, correspondingly reducing the forces they exert when in motion. But this is only half the story, the other half being the engine-tender drawgear. Using an American-type coupling incorporating a friction-damped radial buffer allows the tender mass to be added to that of the engine in absorbing fore-and-aft forces, which from Newton's equation proportionally reduces the resultant accelerations (vibrations) of the engine, which is the important parameter. Put simply, if we can roughly halve the reciprocating masses and double the mass of the locomotive resisting fore-and-aft forces (by incorporating the mass of the tender) then the balancing problem is solved, eliminating the objections to a 2-cylinder machine for high speed. The key is optimum design of the reciprocating parts, and it can be revealed that the pistons, piston rings, piston rods and piston tail rods for the 5AT are already fully specified, the total mass of this assembly being only 200 lb., with a stress-based fatigue life equal to the full expected life of the locomotive. It would therefore appear that the target of 550 lb. for the total mass of the reciprocating parts per cylinder is going to be bettered. Mr. Attewell's other arguments in support of 3 cylinders are rather unconvincing. Adhesion is a complex subject - suffice it to say that there is little practical evidence (especially in Britain!) to suggest that 3-cylinder engines have superior adhesion. And at the kind of running speeds the 5AT would normally be used at, the damping of combustion gas flow through the boiler tubes produces fairly uniform draught on the fire whatever the number of cylinders, as I can attest from having taken thousands of draught readings. Of much greater importance is to dampen the draught peaks due to over-rapid release of steam from the cylinders, and I would remind Mr. Attewell that this problem destroyed the performance of the 3-cylinder "Duke of Cloucester", but not that of the 2-cylinder Caprotti Class 5's! 聽 聽 聽</div></td> </tr> <tr> <td Modified date 04/09/2010 07:19:45 PM></td> <td Last modified by Chris Newman></td> </tr> <tr> <td class="footer_navigation" style='text-align:left'> Previous page: <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/piston-speed-too-high.html" title="Isn't the piston speed of the 5AT going to be too high?" >Isn't the piston speed of the 5AT going to be too high?</a></td> <td></td> <td class="footer_navigation" style='text-align:right'> Next page: <a href="http://5at.co.uk/index.php/faqs-2/valve-gear-questions/hammer-blow.html" title="What about effects of Hammer Blow effects?" >What about effects of Hammer Blow effects?</a> </td> </tr> </table> </td> </tr> <tr > <td > <table width="100%" border="0" cellspacing="0" cellpadding="0" class="footer"> <tr> <td><div>Copyright 漏 2012 5AT Group. 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