# How do you start a BIG engine? **URL:** \ **Category:** Factual Questions\ **Created:** [September 8, 2009, 4:09pm UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299 "2009-09-08T16:09:13Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [September 9, 2009, 1:11am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/21 "2009-09-09T01:11:41Z")
As a side bar, before computers the way pistion rings were inspected is someone would climb into the intake chamber and the engine was rotated with jacking gear until the pistion rings were at the intake ports. This on a two cycle engine. ---
**Author:** ![Kevbo](https://avatars.discourse-cdn.com/v4/letter/k/e47774/32.png) [@Kevbo](https://boards.straightdope.com/u/Kevbo)\ **Post date:** [September 9, 2009, 2:03am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/22 "2009-09-09T02:03:59Z")
Another method is inertial starting: A hand crank, or an electric motor spins a flywheel up to very high speed, then a clutch is engaged, which couples the flywheel through gearing to turn the motor. The hand-crank version was fairly common on large radial aircraft engines. I have had the pleasure of cranking a Stearman up with this. It would not have been a pleasure if the pilot wasn’t well practiced in priming and throttle manipulation, requiring more than one spin-up of the flywheel. ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [September 9, 2009, 2:07am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/23 "2009-09-09T02:07:14Z")
Gasoline engines can be started by injecting and igniting gas in the cylinder that is read to fire. I don’t know if any cars are using the technology but it’s been talked about for years. If a diesel engine uses a common rail fuel system with pressures of 26,000 psi I see no reason why it can’t be done on a large diesel. they would have to have an ignition source added just for starting. ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [September 9, 2009, 3:35am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/24 "2009-09-09T03:35:55Z")
> [@Joe Frickin Friday](#): > > My understanding is that these engines are almost never shut down unless something is _seriously_ wrong with them. What \*\*Snnipe 70E \*\*said. This is dead wrong: not only are they regularly shut down, they are shut down several times in the course of a single berthing manouevre as the master/pilot call for ahead/astern movements. More starts than planned usually happens when something is going wrong. When something is already going wrong and then the engine room calls “only three more starts, Captain” up to the bridge the tension goes up a notch. ---
**Author:** ![Happy\_Fun\_Ball](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/happy_fun_ball/32/17664_2.png) [@Happy\_Fun\_Ball](https://boards.straightdope.com/u/Happy_Fun_Ball)\ **Post date:** [September 9, 2009, 4:20am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/25 "2009-09-09T04:20:08Z")
> [@Tully\_Mars](#): > > I serviced an older Caterpiller dozer years ago that had a two cylinder gasoline engine that was pull-rope-started. When you had the two-cylinder running, you used a hand-actuated clutch to turn the big diesel engine. I have seen this setup also. The gasoline engine was called a pony engine and it would be used to start the diesel. The diesel was from a WWII tank IIRC and was installed in the boat I was on shortly after the war. The boat was a Chesapeake Bay buy boat, and was sail powered before the engine was installed. > [@VunderBob](#): > > The principle invloved (I forget the name, and I’m an electrical enginer; shoot me) is that electrical power isn’t free. if you need a kilowatt to run a load, you need to generate a kilowatt plus the transmission losses to deliver it. Therefore, should the traction motors on the locomtive bog down under load, the increased load will be transmitted back to the alternator, and in turn slow down the prime mover, which you hear. Conservation of Energy? Bang! ---
**Author:** ![VunderBob](https://avatars.discourse-cdn.com/v4/letter/v/839c29/32.png) [@VunderBob](https://boards.straightdope.com/u/VunderBob)\ **Post date:** [September 9, 2009, 9:01am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/26 "2009-09-09T09:01:23Z")
> [@L. G. Butts](#): > > Conservation of Energy? Bang! It’s named for somebody. ---
**Author:** ![Deereman](https://avatars.discourse-cdn.com/v4/letter/d/a3d4f5/32.png) [@Deereman](https://boards.straightdope.com/u/Deereman)\ **Post date:** [September 9, 2009, 9:14am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/27 "2009-09-09T09:14:04Z")
Small gasoline engines were used to crank over hard starting large diesel engines, back when the electric starters weren’t up to snuff. They’re usually called pony starts, donkey engines, or cranking engines and were used on John Deere diesel tractors from 1949-1960. Tiny opposed two cylinder engines or tiny V4s, depending on the tractor. And on Caterpillars too, as was mentioned Here is a video of a pony start Deere, being started: > **[Photo Storage | Photobucket](https://s108.photobucket.com/albums/n8/weirddeere/?action=view¤t=70DStart.flv)** > > Store your photos and videos online with secure storage from Photobucket. Available on iOS, Android and desktop. Securely backup your memories and sign up today! ---
**Author:** ![kferr](https://avatars.discourse-cdn.com/v4/letter/k/71e660/32.png) [@kferr](https://boards.straightdope.com/u/kferr)\ **Post date:** [September 9, 2009, 11:22am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/28 "2009-09-09T11:22:29Z")
I used to work at a natural gas compressor station where the engines were HUGE! We had 7 engines, six were straight 7’s and one was a V-8. The size of the pistons was between the size of a beer keg and 55 gallon drum. The fuel was the same natural gas that they were compressing and they were all started on air. ---
**Author:** ![Tully\_Mars](https://avatars.discourse-cdn.com/v4/letter/t/7ab992/32.png) [@Tully\_Mars](https://boards.straightdope.com/u/Tully_Mars)\ **Post date:** [September 9, 2009, 12:00pm UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/29 "2009-09-09T12:00:42Z")
> [@kferr](#): > > I used to work at a natural gas compressor station where the engines were HUGE! Like [this](http://farm4.static.flickr.com/3542/3399904561_021ea80bf5_b.jpg)? This one is air-started. The air starter makes a high pitched whine that sounds almost like a siren when it starts. The woods in East Texas are littered with these things now and you can hear the starters go “whiiiirrrrrr” from miles away when they start one up. ---
**Author:** ![BlakeTyner](https://avatars.discourse-cdn.com/v4/letter/b/50afbb/32.png) [@BlakeTyner](https://boards.straightdope.com/u/BlakeTyner)\ **Post date:** [September 9, 2009, 4:49pm UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/30 "2009-09-09T16:49:41Z")
Here’s a youtube video of a locomotive starting, taken from inside the engine compartment. Scroll to about the 4 minute mark for the actual startup. It’s an older locomotive, but the concept remains basically the same (modern locomotives often have an engine start button in the cab that automates the fuel priming, etc.) It’s done off of battery power. As mentioned above, except in very specific circumstances, the batteries do not provide any propulsion. [Starting a Locomotive](http://www.youtube.com/watch?v=bNR8dYzeCkc) ---
**Author:** ![gotpasswords](https://avatars.discourse-cdn.com/v4/letter/g/c57346/32.png) [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)\ **Post date:** [September 9, 2009, 4:58pm UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/31 "2009-09-09T16:58:07Z")
How much of a market remains for those gigantic engines? I don’t know about container freight ships, but cruise ships have been diesel-electric for some time now, and the newer ones have an array of small engines so they can only run as much engine as they need to support the current (hah, bad pun…) demands of both the “hotel” load (basically, all of the human comforts above the water line) and propulsion. The ship I was on earlier this year had something like two 8-cylinder engines and three 16-cylinder engines which let them trim their fuel usage anywhere along the range of full power on down to just enough to keep the lights and climate control running while docked. ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [September 9, 2009, 6:09pm UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/32 "2009-09-09T18:09:43Z")
> [@gotpasswords](#): > > How much of a market remains for those gigantic engines? Apparently a lot. The huge engine linked above is a pretty new design. I presume they would not have gone to the expense had there not been a market. It is stated in one of the above links that people who run container ships prefer a single engine, single propeller design. I presume the whole thing driving this are cost of operation concerns and I am guessing one engine/propeller is cheaper to operate than two or more. They also note that the huge engine above is actually very fuel efficient. Another cost savings. I would suppose a cruise ship might have other concerns. A single engine is a single point of failure. More than one engine is probably a good idea for those. ---
**Author:** ![Pushkin](https://avatars.discourse-cdn.com/v4/letter/p/ee59a6/32.png) [@Pushkin](https://boards.straightdope.com/u/Pushkin)\ **Post date:** [September 9, 2009, 6:47pm UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/33 "2009-09-09T18:47:21Z")
> [@Tully\_Mars](#): > > I serviced an older Caterpiller dozer years ago that had a two cylinder gasoline engine that was pull-rope-started. When you had the two-cylinder running, you used a hand-actuated clutch to turn the big diesel engine. On that note I was somewhat disappointed to find out that engines from Zaporozhets weren’t used as [starter motors](http://www.readrussia.com/blog/made-in-russia/00067/) for Soviet tanks. ---
**Author:** ![Myglaren](https://avatars.discourse-cdn.com/v4/letter/m/f1d935/32.png) [@Myglaren](https://boards.straightdope.com/u/Myglaren)\ **Post date:** [September 9, 2009, 10:22pm UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/34 "2009-09-09T22:22:19Z")
My dad was a marine engineer and mentioned on more than one occasion how the diesels were started with a (blank) shotgun cartridge. Come to think of it, I believe I saw this being done on Das Boot. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [September 10, 2009, 1:14am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/35 "2009-09-10T01:14:47Z")
> [@Myglaren](#): > > My dad was a marine engineer and mentioned on more than one occasion how the diesels were started with a (blank) shotgun cartridge. > Come to think of it, I believe I saw this being done on Das Boot. That woudl be a small marine engine probably under 2000 HP ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [September 10, 2009, 1:24am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/36 "2009-09-10T01:24:15Z")
> [@gotpasswords](#): > > How much of a market remains for those gigantic engines? > > I don’t know about container freight ships, but cruise ships have been diesel-electric for some time now, and the newer ones have an array of small engines so they can only run as much engine as they need to support the current (hah, bad pun…) demands of both the “hotel” load (basically, all of the human comforts above the water line) and propulsion. > > The ship I was on earlier this year had something like two 8-cylinder engines and three 16-cylinder engines which let them trim their fuel usage anywhere along the range of full power on down to just enough to keep the lights and climate control running while docked. Freighters and tankers are going to be single shaft with direct drive most of the time. And cost is the factor. On modern cruise ships twin screw. And electric drive with isopod motors. That is a motor hung under the ship some what like an outboard drive on a boat. Manuaverability is the reason. The engines and engine room on some of those ships are strange. The main engines turn generators that feed a main power supply buss. The main engines feed the buss and the main motors and hotel load are both connected to the main buss. Some ships are diesel electric only, some are diesel electric with waste heat boiller and a steam turbine, and some ships are gas turbine with a waste heat boiler and steam turbine. The motors on the new cruise ships are variable speed motors, that is why two motors can run off a main buss with the hotel load. And the motors on these ships are in the range of 43,000 shp or more. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [September 10, 2009, 3:07am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/37 "2009-09-10T03:07:03Z")
> [@Snnipe\_70E](#): > > On modern cruise ships twin screw. And electric drive with isopod motors. That is a motor hung under the ship some what like an outboard drive on a boat. Manuaverability is the reason. An [isopod](http://en.wikipedia.org/wiki/Isopod) is a small, annoying insect with armor plating. Perhaps you meant [Azipod,](http://en.wikipedia.org/wiki/Azipod) which I’ve heard of before. Why are Azipods the weapon of choice for cruise ships, but not for freighters/tankers? ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [September 10, 2009, 4:43am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/38 "2009-09-10T04:43:50Z")
> [@Joe Frickin Friday](#): > > Why are Azipods the weapon of choice for cruise ships, but not for freighters/tankers? $ ---
**Author:** ![Princhester](https://avatars.discourse-cdn.com/v4/letter/p/3e96dc/32.png) [@Princhester](https://boards.straightdope.com/u/Princhester)\ **Post date:** [September 10, 2009, 4:48am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/39 "2009-09-10T04:48:44Z")
> [@Joe Frickin Friday](#): > > Why are Azipods the weapon of choice for cruise ships, but not for freighters/tankers? I’m not completely certain. However, the commercial ship market tends to be dominated by the need for reliability and efficiency, which tends to lead to designs that emphasise simplicity. Azipods have more moving parts, and are necessarily diesel electric which (as said above) is less efficent than just a simple big engine direct driving a simple big prop. Where Azipods come into their own is when manoueverability ranks high in priorities. Cruise vessels already run diesel electric , and they often go to relatively obscure ports which may not have much tug assistance. They also go into/out of ports more often. Commercial vessels tend to go to established ports with tug assistance, and have longer carrying voyages between ports. ---
**Author:** ![Snnipe\_70E](https://avatars.discourse-cdn.com/v4/letter/s/b5a626/32.png) [@Snnipe\_70E](https://boards.straightdope.com/u/Snnipe_70E)\ **Post date:** [September 10, 2009, 4:52am UTC](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299/40 "2009-09-10T04:52:45Z")
> [@Joe Frickin Friday](#): > > An [isopod](http://en.wikipedia.org/wiki/Isopod) is a small, annoying insect with armor plating. > > Perhaps you meant [Azipod,](http://en.wikipedia.org/wiki/Azipod) which I’ve heard of before. > > Why are Azipods the weapon of choice for cruise ships, but not for freighters/tankers? A cruise ship needs mobilty. with AZIPODS and bow thrusters a cruise ship can do turn end for end. a freighter or tanker does not need to make those kinds of turns. [Previous page](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299.md?page=1) [Next page](https://boards.straightdope.com/t/how-do-you-start-a-big-engine/509299.md?page=3)