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| Thread ID: 76369 | 2007-01-30 05:53:00 | Diesel Engines | Bob_Bond (10568) | PC World Chat |
| Post ID | Timestamp | Content | User | ||
| 520594 | 2007-01-30 05:53:00 | Ok this is a totally random question, but something I have been wondering for the last week or so and it's totally bugging me. SickPuppy doesn't know the answer (and he usually knows everything about anything....especially vehicle related :nerd: ) so he suggested I post something here. Has anyone noticed how often diesel engines are left unattended....AND RUNNING!!! I was walking down the platform at Wellington Railway station the other day. There were THREE LOCOMOTIVES....not going anywhere, but all 3 were running. Today there was a remote locomotive on the track that was blocked in by a train that wasn't leaving for another half an hour....but the remote loco was running. Then there's buses. Go to a bus station (a main one in downtown somewhere). Ever noticed how many are left running while the driver sits inside having his cup of coffee or while the driver heads off to do his ablutions. Over the Christmas period I went to the South Island and while I was waiting to check in at the ferry terminal a truck pulls up...the driver gets out and walks off to the truckie kitchen area they have there to make some coffee and replenish his flask and leaves the engine running. Ok so not likely someone will steal a train, a bus or a truck (well, except in the movies....maybe) but in a time when everyone is so concerned about CO2 emissions and stuff....does it make sense that these things are left running? :waughh: I'm sure there must be some logical technical reason for it.....as you can tell I really just want to know and it's really really really really REALLY bugging me :confused: |
Bob_Bond (10568) | ||
| 520595 | 2007-01-30 06:17:00 | It takes more fuel to get the engine up and running than it does to leave it running for an hour, also its best to start engines as least as possible. :p | Chrisn (9819) | ||
| 520596 | 2007-01-30 06:50:00 | A diesel locomotive is actually diesel/electric. The diesel motor generates the eletrics for the motor that drive the train. and I guess all the power for the carriages | plod (107) | ||
| 520597 | 2007-01-30 06:52:00 | I'm no mechanic . . . though I will admit if I could do it all again I might be! :D In respect of trucks . . . . it's probably relevant to diesels not liking the cold . Hmmm . . . . anyway, as they use heat and compression to run, keeping everything warm probably lengthens engine life . Also, the brakes are partially operated by compressed air supplied by the compressor mounted atop the engine . Leaving the engine idling keeps the engine warm and and the air pressure up, which means they're good to go as soon as the coffee and greasy breakfast is finished . There used to be a sensational truckie-stop in Taupo . Breakfasts were outstanding . . . . . if ya sat still for just a minute you could feel the arterial walls slowly thickening . . . . :rolleyes: T |
allblack (6574) | ||
| 520598 | 2007-01-30 07:14:00 | suferjoe...where are you ;) afaik big deisels can be hard on starting gear so often they leave them running in case they can't get them going again. exspecially so in really cold weather. also batteries actually take a long time to recharge fully, constant stop starting is not good for them. smaller deisels can be often turboed so they have to leave then running while the turbo and oil cools down. a 5 min wait is not uncomman so often its easier to just leave it running and go do whatever buisnees needs doing. |
tweak'e (69) | ||
| 520599 | 2007-01-30 08:40:00 | The pistons are not a tight fit as with petrol. They slap around when cold and take a while to heat up and fitting the bore. While the piston rings are meant, as in petrol motors, to just fit the bore and therefore add to the engine compression, diesel compression is a lot lower and therefore needs the motor to keep running to maintain the compression. | Bryan (147) | ||
| 520600 | 2007-01-30 19:34:00 | Diesel locos are best left idling as it keeps the engine worm. Diesels don't like being run from cold with a load that's why firetrunks have water preheaters when parked at firestations. From memory a DC class loco uses about 1 gallon per hour idling which is not much.. | paulw (1826) | ||
| 520601 | 2007-01-30 20:17:00 | The pistons are not a tight fit as with petrol. They slap around when cold and take a while to heat up and fitting the bore. While the piston rings are meant, as in petrol motors, to just fit the bore and therefore add to the engine compression, diesel compression is a lot lower and therefore needs the motor to keep running to maintain the compression. What rot - diesels are compression ignition engines and thus have much higher compression ratios than petrol ones. This higher compression ratio means a lot more energy is required to turn them over in starting, however a lot of the reason for leaving a diesel running derives from the times when large engines had to have donkey engines to get them started and it was such an effort to get them going again. |
dvm (6543) | ||
| 520602 | 2007-01-30 20:17:00 | The pistons are not a tight fit as with petrol. They slap around when cold and take a while to heat up and fitting the bore. While the piston rings are meant, as in petrol motors, to just fit the bore and therefore add to the engine compression, diesel compression is a lot lower and therefore needs the motor to keep running to maintain the compression. Actually Bryan, this is completely wrong. A Diesel engine has a much higher compression ratio than a petrol engine. en.wikipedia.org |
Mackin_NZ (6958) | ||
| 520603 | 2007-01-30 21:12:00 | That's brilliant... Makes a lot of sense and has been really helpful. Thanks everyone - I'm not very mechanically minded and whilst I don't really understand everything that everyone has written at least I know there are some technical reasons for them leaving them running. On a related note however, as I was walking up the platform at Wellington Railway station this morning there was a loco stopped along the platform and it was SWITCHED OFF!!! (Has anyone from TollMetro been reading this? lol) Um....earlier someone mentioned locos are diesel electric. This may be true, I don't know, but I have noticed that the "luggage" car has a generator which is used to supply the electricity to the carriages. This is evidenced by the carriages having electricity before the loco is attached and only the luggage car generator engine is running. I don't know if the loco takes over this function when it is attached. All in all, a great response. Thanks all.... Keep posting if you have more info tho. |
Bob_Bond (10568) | ||
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