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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 | ||
| 520604 | 2007-01-30 21:21:00 | i think what bryan was trying to say is the pistons are loose when cold which looses a lot of compression compared to a petrol motor which dosn't loose as much compression when cold. however its hard to compare as i don't think anyone makes petrol engines of that size so its proberly not relavent. you can't really compare large deisels to small high speed deisels. | tweak'e (69) | ||
| 520605 | 2007-01-30 21:34:00 | Found this link (www.epa.gov) which is quite interesting. | Mackin_NZ (6958) | ||
| 520606 | 2007-01-31 03:09:00 | OK . . let me nibble at some of this . . . Diesel piston/fitting/slap? Nope . . diesels are fitted much more critically than their gasoline counterparts . . . . so much so that the pistons are matched to the cylinders as the engines are first manufactured . . . and that clearance is maintained at rebuild too . . . . The running diesel locomotives you saw are usually left running because they are indeed making electricity to keep certain things up and running . . . but here in the US . . they are currently frowning upon leaving them running for days or weeks at a time . It is just not economical to let them run like that . Diesels are also "dirtier" when idling . . ergo they make much more photochemical smog at that time but less nitrous oxide . Critical to a diesel engine is the operating temperature . . they want them at 200 degrees F . . . or about 93 degrees C . Just a few points below boiling temp of water at sea level is the best . Newer Detroit 60 series run happily at 240F/115 . 5C, and at that get the least cylinder wear and soot formation in the oil . 1,000,000 miles or 1,609,344 kilometers is just a break-in for engines any more . Some locs run from the day they are born until they need to be retired . Lubricants are even changed while the engine is running . Leaving a big rig running at a truck stop is usually done for economy purposes . Some are air started, some are electrically started like other autos . Some run air conditioning all the time to keep the cab cool . . . . again, not a really good enough reason to leave them running in my opinion . Some run refrigeration units to keep the cargo cold . . . like meat or produce . . . but these units are phased out with the advent of refers built into the trailers and cargo areas . OK . . . the air brakes part . . . partly wrong . . but a good shot anyway . Actually, air brakes have a system that sets the brakes (very hard) with large springs that are released when the air is charged into that portion of the system . These are called "spring brakes" and they are like parking devices to keep the vehicle standing where they are stopped . Air is needed to release these brakes . . so running the engine is not necessary for keeping the vehicle stationary . These spring brakes, by the way, can be used to emergency stop a semi . . but you gotta be sure you want to "grenade" the brakes in a situation like a downhill runaway situation . Tires will be ground down to the rims and loss of control happens . . but this is a life-and-death situation, last ditch attempt . One thing to consider is that diesels do not like to start when cold without some extra help . . sometimes in the form of an ether injector, a pony engine to heat up the head(s) or use of a more volatile fuel to crack them off . Starting an engine is when the wear is at it's highest . . . and some companies like their engines left running if the vehicle is going to be parked for less than a few hours anyway to save early repair and rebuild costs . Diesel engine in very cold climates are left running all year long as they will not start until the engines are heated and even then they are hard to coax into life . The Alaskan pipeline was one example where the engines were left running all year long . Turbo chargers and superchargers are not even a factor while starting an engine . . . although the two-cycle Detroits need air flow to establish the direction of exhaust flow at starting time . These two-cycle and some four-cycles too can actually run backwards . I have had many Macs come in with the exhaust going out the air filter and then the oil and water pumps cannot work correctly . . . this usually kills the engine . (Some drivers complained about having 10 gears in reverse and only 3 forward . . duh!) Detroit 53's and 71's were the last of the two-cycle diesels that ran around here in the US . . . they are almost all long gone by now . The produced a lot of power and ya hadda drive them like you hated them . . . wind the engine to the governor and shift, wind and shift again and again . They smoked too much for John Q . Public, and although the smoke they saw was not totally responsible for smog, it was what they saw and screamed about it . Some truck drivers will leave their engines running when they pull off the road to sleep per DOT regulations . In the US drivers are not supposed to run for more than a set number of hours a day without sleep . They nap for a few hours and get their logs "cheated" and then go on . Most semis these days have "condos" or sleepers that are really posh apartments with satellite television, cellphones, vcr's, dvd's, large beds and refrigerators, stoves, microwaves and other creature comforts . Some companies prefer to hire husband and wife driving teams, as they take a lot better care of the trucks and driver safer too . I worked on reciprocating multi-fueled engines with pistons so big you could hold a waltz on them with two couples . . . . . One was over 13 meters in diameter . . . (if that's about 45 feet!) . It ran at a top speed of 22 rpm . |
SurferJoe46 (51) | ||
| 520607 | 2007-01-31 05:08:00 | I find that hard to believe!,what kind of car was that? | Cicero (40) | ||
| 520608 | 2007-01-31 05:27:00 | O OK . . . the air brakes part . . . partly wrong . . but a good shot anyway . Really???? "A good shot"?? Hmmmm . . . . . . . ::confused: |
allblack (6574) | ||
| 520609 | 2007-01-31 05:40:00 | Turbo chargers and superchargers are not even a factor while starting an engine . . . although the two-cycle Detroits need air flow to establish the direction of exhaust flow at starting time . These two-cycle and some four-cycles too can actually run backwards . turbos, however, are a factor when turning off, as a result many vehicles have "turbo timers" to keep the engine running for a few minutes after the driver has told it to turn off . |
motorbyclist (188) | ||
| 520610 | 2007-01-31 06:39:00 | That is because the shaft, bearing, impeller, and turbine can rotate at speeds in the tens or hundreds of thousands of RPM and just stopping them by turning off the engine can damage the bearing. I drove a bulldozer once that had a donkey motor and it was a very complicated procedure to start it up. We left it going for lunch but killed it at knock off. I guess that people who drive diesels (eg train and truck drivers) are less likely to be paying the fuel bill |
joemac (9739) | ||
| 520611 | 2007-01-31 08:07:00 | As I drive a Turbo diesel truck I know that they have a timer on that will stop the engine after 3 - 5 minutes. As the driver I already have the key in my pocket. You can also leave the engine at idle for a few minutes as well before leaving the truck. I know nothing about locomotives. I suspect they can be diesel/electric and are possibly running a generator to charge batteries. |
Sweep (90) | ||
| 520612 | 2007-01-31 08:19:00 | Thanks SurferJoe46, I've learnt a lot. | Bryan (147) | ||
| 520613 | 2007-01-31 09:07:00 | That is because the shaft, bearing, impeller, and turbine can rotate at speeds in the tens or hundreds of thousands of RPM and just stopping them by turning off the engine can damage the bearing. ........ ....... I guess that people who drive diesels (eg train and truck drivers) are less likely to be paying the fuel bill its not the rpm of the turbo but the heat soak that fries the oil when the oil stops being pumped around once the motor has stopped. just need to wait till the turbo and oil temps have come down before turning off. yeah if they are not paying the fuel bill i guess they won't care. however owner drivers surely do care. |
tweak'e (69) | ||
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