Category: Mechanical

Engines which connect the world

With the word connection, first thing that comes to everyone is probably the internet itself or fibre optic cables. Well, this one is for the propulsion machinery that makes the real connections possible. Internal Combustion Engines which propel the major share of ocean going carriers across the world’s oceans.

Two stroke, low speed, direct coupled, crosshead type, water cooled, turbocharged, diesel injected, piston cooled, continously rated, reversible engines with external cylinder lubrication. While that might look like a lot of explanation for an engine, there still are a lot more that can be added to differentiate a particular build of these massive prime movers.

While two stroke engines are facing near extinction on land for a variety of reasons, at sea, they are only going from strength to strength and a whole industry is dedicated to take this piece of technology to ensure that producers and consumers stay connected across the continents. Two stroke marine diesel engines propel the major share of world’s commercial vessels. The only competing alternative prime mover for these being turbines and electric motor based flex/pod propulsion.

These engines are not in the league of massproduced car/bike engines churned out at the rates of one piece every 10 minute (or lesser). Each marine diesel is tailored for a specific carrier (ship) right from the ship’s design stage and is assembled inside the hull during ship building. That doesn’t mean that there are standard models available from the producers. There are, but these are built to order and there is no one size suits all on offer.

Though the names suggests that they burn diesel fuel, it may be noted that these engines are built to burn far inferior quality fuel compared to the high speed diesel fuel that cars/truck engines burn. Marine diesels rather use Heavy fuel oil, the heaviest fraction of crude distillation, just above tar. HSD is rarely used to flush these engines prior to a an overhaul or so. A comparison to perceive the amount of power that these machines produce.

  • Peak power output of the 796 cc engine of  India’s best selling hatchback : 48 BHP @ 6000 RPM
  • Peak Power output of  main propulsion engine of the ill fated  of  Exxon Valdez : 31,650 BHP @ 79 RPM. ie; ~ 660 Maruti Alto 800s.

Corporations leading the industry and innovations to existing two stroke marine engines’ technology are Finnish giant Wärtsilä , Swiss corporation Sulzer and Dutch-Danish MAN B&W Diesels. As rightly titled in this video by Wärtsilä, these machines really are The Engines of Industry. Imagine them not working for a few days! No more fun.

The fading charm of two strokes

What are two stroke engines? (Yes, this is about engines)

As always, the wikipedia article briefly explains what two stroke engines are, but that’d hardly help to recognise the last few of these on Indian roads. If you ever felt that odd looking bike on road is making shriller noise ands emits a bit more smoke than the other bikes on road, good chance that those are two strokes, which ruled the Indian roads in another era, the 1970s and the 80s and well into the 90s. In case you recognize the Rajdoots, Yezdis and the Yamaha RX100s and RD350s, Bajaj Chetaks, Lamby, Lambretta, Priya, Vijai Super, LML Vespa, Suzuki Shogun, Samurai, Tamil Nadu’s own TVS 50, Bajaj RE Autos and thus goes the list. There still are a quite a lot of these remaining in Indian roads, driving memories of generations which grew up seeing/riding these vehicles.

Why Two Strokes a few decades back?

While I am not sure of the business reasons why these engines where chosen over four stroke counterparts in those days, following things would definitely have featured in the list when the decision was made.

  • Lesser moving parts compared to four strokes, easier and less expensive to manufacture.
  • Low on maintenance. (again due to lesser moving parts)
  • Higher Power to Weight (Size) Ratio. Not a major decider for 2/3 wheelers, but a definite winner for two stroke engine technology.

Why Two Strokes are getting removed from streets?

  • Two strokes do not have valve arrangements, rather have intake and exhaust ports, which are controlled by the reciprocating piston’s movement. While this results in minimum moving parts, it also results in loss of efficiency because a part of the fresh charge (air fuel mixture) entering the combustion chamber will be lost without getting burnt. That’s like, your vehicle doesn’t move as much as the fuel is worth! Pretty big sin given the high price of fossil fuels.
  • This inefficient combustion results in low fuel efficiency and increased pollution due to the unburnt air fuel mixture.
  • In an era where the fossil fuels are fast getting consumed, inefficient fuel utilisation and pollution are definitely not desired.

The new stringent rules on pollution control and fuel efficiency and market demand for more mileage per litre of fuel pushed out these machines from  production and many of the above listed vehicle manufacturers, who could not adapt to the technology change had to shut down shop in India. There still are fans of two stroke bikes, who cherish the quick pick up and the head turning shrill noise that these machines make. Yamaha RX 100s, Bajaj Chetaks can still be commonly found in almost all Indian roads, where as Jawa, Yezdi and RD 350s have become pride posessions and are becoming rarer by the day.

After reading this much, in case you concluded that two stroke technology is a thing of the past, there you got it wrong. Two stroke engines are still very much in use and in the largest of possible sizes propelling behemoths of ships across the world’s oceans. Though not exactly similar in construction compared to the smaller petrol two strokes, large, slow speed, direct coupled, diesel two stroke engines propel majority of the world’s merchant marine fleet, the backbone of all the global resource availability in modern times.

Engines : Are we not ungrateful to them?

5th of June, World Environment Day (WED). Naturally that would make the protagonist of our story  the villain. Engines, those which spit out tonnes of polluting gases by burning all the non renewable fossil fuels and thus taking the economies forward in the polluted world!

One of the biggest inventions of the 19th century, the world is where it is today, propelled largely by the smoke spitting internal combustion engines, be it your automobile engine, jet engine, diesel generator or any other prime mover.  While we have calendar days to celebrate all the possible “days“, we seem to have taken for granted the contribution that these poor machines have made towards mankind’s progress. Why? Because, they don’t create noises, unless we press them hard, or because we have a conflicting green day to celebrate?

Think of one day when all engines of the world getting their own brains (brains like  Albert Einstein’s + Karl Marx’s) and souls (?) too. United they decide to take a break for a day! Brilliance it will be, aircrafts falling down from sky, Ships floating clueless at high seas, Daredevils dropping down from mid air like apples on Newton’s head and what not. Space stations might survive.  No water, no power, no phone, defunct cities and forget the stock exchanges. Dude! No internet either. What? No facebook? Probably that makes it sound closer to apocalypse. Yeah! Pray engines don’t get a life of their own without we turning the keys, pressing the button or kicking the lever. As is human, we’ve taken them for granted. Hopefully Radiator Springs celebrates WED as World Engines’ Day. 😀

Will the number of engines made around the world after the IInd world war surpass the number of humans born ?

Though almost all in the civilised society is in one way or other, dependent on engines, awareness of what happens within the muscular metal blocks is still minimal. A basic understanding will definitely help save a few bucks from the mechanics who act up and scare the life out of you even if it’s carbon accumulated spark plug that’s in question. Check out this video showing assembly and operation of a Ford Duratec engine. Great video showing the myriads of parts that make up an engine and excellent animation of four stroke engine’s working.

Long live, mechanical marvels. I shall talk more about you later.