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Sunday, 17 April 2011

Engineering as it used to be–Part 4a

For those of you who wanted some technical details about my last post on Engineering as it used to be.

What you are seeing in this old and grainy movie, is the upper pistons and cross heads of a Doxford engine moving up and down.

This is the upper piston reciprocating (Big word) attached by side rods conveying power to the crankshaft. At the same time there is a lower piston travelling in a reverse direction. When at their closest point, Heavy fuel oil is injected in to the space which ignites, and forces the pistons apart. The running speed varied from about 30 RPM to 120 RPM. Consider that your diesel driven car’s engine usually runs between 1000 RPM and 4500 RPM.


Just so you know.


  1. Captain Haddock17 April 2011 at 19:10

    "Cor, lumme Number One" .. ;)

    My personal experience of Marine motive power was limited to titchy (by comparison) Perkins diesels or Johnson outboards ..

  2. The modern engines are much smaller and higher powered than the old dinosaur doxfords. However the old engines were easier to work on. No torque settings in those days. Everything was tightened up using a large spanner and a twenty eight pound hammer.

  3. I was a test squad plumber working on Invincible for two years during her build an I frequently spent time in her engine rooms. The sight of a 'spare' gas turbine hanging from what appeared to me to be thin steel hawsers has stuck with me along with the time we paced out her gearbox which was longer than a double decker!

    Mind she could do at least 34 knots and exit port like a speed boat with here turbines engaged, according the trials squad.

    Sad to see her 'berthed in Turkey' awaiting demolition.

  4. It's sad to see any ship laid up ready to be turned into razor blades.
    People forget that these ships were actually "home" to so many, for so long.

  5. Captain Haddock18 April 2011 at 09:55

    "People forget that these ships were actually "home" to so many, for so long" ...

    Amen to that, I've never encountered anywhere which can match, let alone beat the atmosphere of a Mess Deck (in all its moods) ..

    And as for Mess Deck humour .. the so-called professional comics would do well to serve their apprenticeship with the RN ..

  6. Although never serving myself during my two years on Invincible I came to regard her as 'my ship' even though I left her every day at 4-00 pm Monday to Friday and completely abandoned her during the weekends and holidays.

    Odd really. Even when fitting out two ex-ammuntion barges berthed aft of Invincible which were to be used as test bed for hydrogen peroxide engines similar to those in HMS Excalibur and HMS Explorer.


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