ctaboy Posted January 21, 2009 Report Share Posted January 21, 2009 How come when buses enter the terminal/layover,the operator either put the bus in nutral or on the emergency brake. After that, it sounds like the engine just changed. Quote Link to comment Share on other sites More sharing options...
cta_44499_FG Posted January 21, 2009 Report Share Posted January 21, 2009 How come when buses enter the terminal/layover,the operator either put the bus in nutral or on the emergency brake. After that, it sounds like the engine just changed. The operator wouldn't (or shouldn't I should say) be putting the emergency brake on unless the parking brake fails. And they put the parking brake on so the bus doesn't roll off on its own. Neutral only stops acceleration, it doesn't prevent free-rolling. Quote Link to comment Share on other sites More sharing options...
T8H5307A Posted January 21, 2009 Report Share Posted January 21, 2009 The operator wouldn't (or shouldn't I should say) be putting the emergency brake on unless the parking brake fails. And they put the parking brake on so the bus doesn't roll off on its own. Neutral only stops acceleration, it doesn't prevent free-rolling. The buses have a engine fast idle switch which only works when the bus is in neutral and the parking brake is applied, so this may be the difference in engine sound you speak of Quote Link to comment Share on other sites More sharing options...
Guest Posted January 21, 2009 Report Share Posted January 21, 2009 The buses have a engine fast idle switch which only works when the bus is in neutral and the parking brake is applied, so this may be the difference in engine sound you speak of Hi Eddie, The Pace Nabis, if you dont switch on the "Fast Idle" when its in park the bus will shut down after five minutes. I wonder if CTAs are like this as well. Quote Link to comment Share on other sites More sharing options...
trey824 Posted January 22, 2009 Report Share Posted January 22, 2009 Hi Eddie, The Pace Nabis, if you dont switch on the "Fast Idle" when its in park the bus will shut down after five minutes. I wonder if CTAs are like this as well. ok first off buses and trucks transmissions are not equipped with a park feature it is nuetral and the shut off is not what happens the transmission will automatically shift into nuetral for cta buses due to different engines. Quote Link to comment Share on other sites More sharing options...
T8H5307A Posted January 22, 2009 Report Share Posted January 22, 2009 The New Flyers and Nabi's shut off after 15 mins regardless of the fast idle switch. The Nova's shut down after 30 mins. The only way around this is to switch the bus to "rear run". Quote Link to comment Share on other sites More sharing options...
ctaboy Posted January 31, 2009 Author Report Share Posted January 31, 2009 i'm sorry on the high floor buses, i thought those said emergency brake,but it said parking brake. Quote Link to comment Share on other sites More sharing options...
jacksone44 Posted January 31, 2009 Report Share Posted January 31, 2009 Is it me or does NF's 1430-1629 operate at a lower RPM than 1000-1429? they seem a tad bit quieter than the earlier ones... Quote Link to comment Share on other sites More sharing options...
jajuan Posted January 31, 2009 Report Share Posted January 31, 2009 Is it me or does NF's 1430-1629 operate at a lower RPM than 1000-1429? they seem a tad bit quieter than the earlier ones... I never noticed. The only difference I really noticed is 1630 and above being a bit quieter because of the lower weight materials used in their body frames. 1430-1629 sound just like the rest of the pre-Option 3 NFs to me. Quote Link to comment Share on other sites More sharing options...
Chicago49xxx Posted January 31, 2009 Report Share Posted January 31, 2009 Is it me or does NF's 1430-1629 operate at a lower RPM than 1000-1429? they seem a tad bit quieter than the earlier ones... Actually there is a difference starting with 1430 i dont know if its a completely different engine but it has something to do with the ep standards for the 2007 and up diesel engines the ones we have at chicago jerk when taking off i had a number of people who almost fell on my bus from leaving a service stop and if you notice the exhaust pipe on the 1430s and 1440s looks as if it was brand new on the inside its not covered with soot or anything while 1000-1429 the inside of the exhaust pipe is black maybe the cta ordered a couple like this to test them out Quote Link to comment Share on other sites More sharing options...
Guest Posted January 31, 2009 Report Share Posted January 31, 2009 ok first off buses and trucks transmissions are not equipped with a park feature it is nuetral and the shut off is not what happens the transmission will automatically shift into nuetral for cta buses due to different engines. I meant when the bus parking brake is on. Quote Link to comment Share on other sites More sharing options...
jajuan Posted February 1, 2009 Report Share Posted February 1, 2009 Actually there is a difference starting with 1430 i dont know if its a completely different engine but it has something to do with the ep standards for the 2007 and up diesel engines the ones we have at chicago jerk when taking off i had a number of people who almost fell on my bus from leaving a service stop and if you notice the exhaust pipe on the 1430s and 1440s looks as if it was brand new on the inside its not covered with soot or anything while 1000-1429 the inside of the exhaust pipe is black maybe the cta ordered a couple like this to test them out I see. I don't get to ride NFs numbered between 1430-1629 much. I mostly just get to ride 1000-1429 from either Kedzie, 74th or Chicago when I'm closer to home or one of Kedzie's 1630-1724 and 74th's 1725-1760. Whenever I need a NP or 103rd NF it's always among 1761 and above. Quote Link to comment Share on other sites More sharing options...
speedracer1407 Posted February 2, 2009 Report Share Posted February 2, 2009 I never noticed. The only difference I really noticed is 1630 and above being a bit quieter because of the lower weight materials used in their body frames. 1430-1629 sound just like the rest of the pre-Option 3 NFs to me. I can't see why lighter materials would make the engine inherently quieter unless they had greater sound- deadening properties. But as I understand it, the primary weight-saving difference is the use of a carbon-steel frame, which on a body-on-frame bus would have little effect on the engine compartment. The real culprit is likely the entirely different engine used on 1630 and above: an 8.9 liter Cummins ISL instead of the the 10.8 liter ISM on the earlier #1000s. While the two produce the same power and similar torque, the engines have different design lineage, so it's sensible to assume that this accounts for the slight difference in overall noise. Quote Link to comment Share on other sites More sharing options...
daerah Posted February 2, 2009 Report Share Posted February 2, 2009 The New Flyer 1000s have a 15 minute idle period before shutting down The NABI 7500s have a 30 minute idle period before shutting down (As mentioned before, that idle timer period can be over ridden if it's switched to Rear Run mode) Hence the buses run all night in extreme cold weather And if you place the transmission in N Neutral...without setting the parking brake, the bus will not ride away, as long as it's still switched on either in "Day Run" or "Night Run"....it's being held by a combination of electronic mechanisms...(not including the parking brake) if the bus however, shuts off... either in "Engine Stop" or "Night Park/ "lights"..the bus will roll away. The mentioned electronic mechanism is one...if the back door is unlocked, the transmission interlock is activated, which disables the use of the engine throttle/ accelerator, and in turns, it actives part way of the service brakes. Or, if the back door isnt unlocked, and if the transmission is in "D" Drive or "N" Neutral...after the bus has come to a complete stop, a couple seconds afterwards, the transmission slips into sort of a half-way neutral effect. "Trans-brake"...which also holds the bus as an added safety feature, as we're told. If the driver gets up out of the seat, or "forgets" to set the parking brake...the 'wheelchair/kneeler" beeping sound, will sound...and a warming light will come on.. "Driver Seat Alarm"...meaning the bus is holding itself for a safety..but once its off...it will roll away..so set the parking brake...lol is basically what the bus is telling us. Either way...the bus is always supposed to be in neutral and parking brake applied, if our foot isnt on the on or covering the brake. Just makes sense. Fast idle does make a difference in sound. And with the ISM series buses...a lot of times, it sounds louder than it really is, because a lot of them have the 'engine fan' on...and you hear blowing, humming along with engine rpm'...some of the ISL series have their engine fans on...and it sounds just as loud. I'm not familiar with the NOVABus 6400 idle timer period I dont belive the Flxible Metro 6000s have a idle timer period Quote Link to comment Share on other sites More sharing options...
trey824 Posted February 3, 2009 Report Share Posted February 3, 2009 I can't see why lighter materials would make the engine inherently quieter unless they had greater sound- deadening properties. But as I understand it, the primary weight-saving difference is the use of a carbon-steel frame, which on a body-on-frame bus would have little effect on the engine compartment. The real culprit is likely the entirely different engine used on 1630 and above: an 8.9 liter Cummins ISL instead of the the 10.8 liter ISM on the earlier #1000s. While the two produce the same power and similar torque, the engines have different design lineage, so it's sensible to assume that this accounts for the slight difference in overall noise. its not only the weight reduction the buses have a more feul effecient cummins engine.also i prefer 1630 and higher because the lower numbers can get irratating at times. Quote Link to comment Share on other sites More sharing options...
RW 77 Operator Posted February 12, 2009 Report Share Posted February 12, 2009 Hi Eddie, The Pace Nabis, if you dont switch on the "Fast Idle" when its in park the bus will shut down after five minutes. I wonder if CTAs are like this as well. The New Flyers shut down at 15 minutes, fast idle or not. The Novas and Nabi artics run longer. The TMCs never shut down. I don't remember any of the Flex's ever shutting down. I don't know about the rest. Quote Link to comment Share on other sites More sharing options...
ctaboy Posted February 18, 2009 Author Report Share Posted February 18, 2009 The operator wouldn't (or shouldn't I should say) be putting the emergency brake on unless the parking brake fails. And they put the parking brake on so the bus doesn't roll off on its own. Neutral only stops acceleration, it doesn't prevent free-rolling. what I ment was, why does the bus idles after parking brake is applied. Quote Link to comment Share on other sites More sharing options...
speedracer1407 Posted February 18, 2009 Report Share Posted February 18, 2009 what I ment was, why does the bus idles after parking brake is applied. The phrasing of your question is a little unclear, but I presume your original question is something like this: "Why does the sound of the engine change when the driver puts the bus in neutral and/or applies the parking brake?" I'm not an operator, but the principle behind why the engine sounds changes when an automatic transmission with a torque converter (which is virtually all auto transmissions) is put into neutral applies to cars, buses, and trucks. An automatic transmission uses a torque converter to transmit power from the engine to the transmission. The simplest way of describing how torque converter works is comparing it to a pair of fans. If you put two fans face-to-face, and turn only one fan on, the airflow hitting the "off" fan will cause it to rotate. A torque converter is sorta like two sealed fans, except that one fan (on the engine side) pushes a viscous fluid onto a facing fan (the transmission side) to get the bus moving. This indirect connection between the engine and transmission allows the engine to stay running even when the bus (and therefore the transmission) is stopped. But even when stopped, when the engine is idling, it's still "trying" to push a bit of fluid through the torque converter, so it's under a wee bit of load. When the operator selects neutral, the transmission completely disengages from the engine, and the engine is free to spin without havng to push fluid around in the torque converter. The sound of the engine changes then because it's a)not under load, and is able to idle a little bit faster than it would if it were engaged to the transmission. This is a VERY basic explanation of how a an automatic transmission w/ torque converter works. But a good site for visuals and such is www.howstuffworks.com. There, you can search for torque converter or automatic transmission and get a good step-by-step explanation of how these things work. Quote Link to comment Share on other sites More sharing options...
tonytavell Posted March 30, 2009 Report Share Posted March 30, 2009 doesn't the 5800s,both PACE and CTA 6000s,and the 7500s all have the Detroit Diesel engines ? Quote Link to comment Share on other sites More sharing options...
Guest Posted March 30, 2009 Report Share Posted March 30, 2009 doesn't the 5800s,both PACE and CTA 6000s,and the 7500s all have the Detroit Diesel engines ? Yes, the said buses are equipped with Detroits. Quote Link to comment Share on other sites More sharing options...
tonytavell Posted April 4, 2009 Report Share Posted April 4, 2009 Every time I boarded a 14 being ran by a NABI (when they were in service), when they pull into Washington/Jefferson, the driver applies the brake and then it idles, does any NABI drivers ever have the fast-idle switch off ? Quote Link to comment Share on other sites More sharing options...
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