Difference in kneeling mechanisms - HF vs LF models

[Acela Express]

This topic is geared more for the mechanics.

 

As the topic states: what exactly is the difference between the kneeling mechanisms of the RTS' vs. (example) O7 NGs? Even before I came on the job, I used to see operators kneel the RTS, but on an heavy trip, if you drop the kneel, it's a good chance it won't come back up, unless you do the master knob trick (switch off then back to "lights" quick), and sometimes that doesn't even work. However, with the newer LF models, for example: the NGs, dropping the kneel is pretty easy as they'll come back up no matter how packed your bus is.

 

So, what's what?

 

BTW, a classmate of mine told me a dispatcher told her a trick of how to get the RTS' kneel back up, by pulling the park brake, making sure "Fast Idle" is ON, and build the air pressure depressing the accelerator, which, according to her, seems to work.

[East New York]

This topic is geared more for the mechanics.

 

As the topic states: what exactly is the difference between the kneeling mechanisms of the RTS' vs. (example) O7 NGs? Even before I came on the job, I used to see operators kneel the RTS, but on an heavy trip, if you drop the kneel, it's a good chance it won't come back up, unless you do the master knob trick (switch off then back to "lights" quick), and sometimes that doesn't even work. However, with the newer LF models, for example: the NGs, dropping the kneel is pretty easy as they'll come back up no matter how packed your bus is.

 

So, what's what?

 

BTW, a classmate of mine told me a dispatcher told her a trick of how to get the RTS' kneel back up, by pulling the park brake, making sure "Fast Idle" is ON, and build the air pressure depressing the accelerator, which, according to her, seems to work.

 

They are very similar in technology. Both the RTS and the Orion VII use Arvin Meritor axles. The airbags are what deflate and inflate. The thing you have to remember is the youngest RTS' in the fleet are 12 years old. That's about 550,000 kneeling cycles. Low floors get like that as they get older too.

 

In addition, the RTS is not only heavier, but it holds more passengers which makes it even heavier!

[Via Garibaldi 8]

They are very similar in technology. Both the RTS and the Orion VII use Arvin Meritor axles. The airbags are what deflate and inflate. The thing you have to remember is the youngest RTS' in the fleet are 12 years old. That's about 550,000 kneeling cycles. Low floors get like that as they get older too.

 

In addition, the RTS is not only heavier, but it holds more passengers which makes it even heavier!

 

So what about MCI's? Some B/Os kneel the express bus at every stop, particularly on the Bus routes. I feel like an old man getting on, but it actually does help because the steps can be high esp. if you're stepping on from the street as opposed to the sidewalk. I always worry about them breaking down, but the older ones more so. It has been a problem in the past, where the bus had to be put out of service , but I think the newer MCIs can handle the constant kneeling more.

 

I remember once though my uncle was driving a bus uptown in the city and he had to let some people off and make them walk up the hill and get back on. lol Talk about a ghetto bus. That was the old days though.

[Joel Up Front]

And on LI, why do some of the NGs remain quiet (except for the alarm) when the kneeler is activated but on others they're as loud as an Orion V?

[BZGuy]

ENY hit it on the head. The RTSs are older and heavier which is why they have more problems with the kneelers. Give it a couple more years and the O7s will be doing the same thing. I hope MTS has improved the kneelers in the new RTSs....that's the only weakness I think those buses have.

 

Now on the my favorite subject....the MCIs. New or Old they are gonna have problems, it depends on the depot's maintenance. Spring Creek,Yonkers and Eastchester have excellent maintenance so you don't really see a problem. I would be wary about kneeling a College Pt,La Guardia or JFK MCI. I don't know if the shows the B/Os where the leveling valves are in the rear right engine compartment, but knowing how to use them to get the kneeler back up has save my ass a few times.

 

Joel, I'm assuming some buses have that annoying as hell alarm disconnected. When I drove RTSs in CT all of buses had that alarm and magically one by one they got disconnected!

 

Acela, did they tell you NOT to kneel the buses in the winter time? At CTTransit they don't want the guys to kneel the buses during the winter time because all the slush and ice that get thrown up into the wheel wells have a tendency to "freeze" the kneeler down.

[roadpilot]

On the older MCI's you have to pull the brake and put the bus in neutral,to use the kneeler, the 4000's and newer you don't have to that.

[roadpilot]

About the leveling valves that is strictly a maintence thing we are not to touch them. Hey if I brake down so be it.

[Acela Express]

Thanks for the replies, fellas.

 

Though the latest RTS' in our fleet are 12 years old, and they all have kneeling issues when crush loaded, my curiosity now goes for the 99-00 C40s at Jackie Gleason, which don't seem to have any problem with kneeling abilities, unless I'm mistaken? We're talking just over 10 years, which are subject to same issues, and just as many (or close) kneeling cycles as the latest RTS in the fleet.

 

 

BZGuy,

 

No, I wasn't told to avoid using the kneeler during the winter.

It's something I'll ask around though, or if any of my fellow operators can chime in on the issue?

[jemcclain1]

This topic is geared more for the mechanics.

 

As the topic states: what exactly is the difference between the kneeling mechanisms of the RTS' vs. (example) O7 NGs? Even before I came on the job, I used to see operators kneel the RTS, but on an heavy trip, if you drop the kneel, it's a good chance it won't come back up, unless you do the master knob trick (switch off then back to "lights" quick), and sometimes that doesn't even work. However, with the newer LF models, for example: the NGs, dropping the kneel is pretty easy as they'll come back up no matter how packed your bus is.

 

So, what's what?

 

BTW, a classmate of mine told me a dispatcher told her a trick of how to get the RTS' kneel back up, by pulling the park brake, making sure "Fast Idle" is ON, and build the air pressure depressing the accelerator, which, according to her, seems to work.

 

I could do you one better Acela as far as building air pressure back up faster. Engage the parking brake, put the bus in neutral. Then hold the Auxilary Interlock switch and step on the accelerator. Just don't rev the engine too fast it could become quite noisy. And by the way most drivers would tell you not to kneel the bus in the winter time. You would really be delayed using the kneeler. Also when there is snow and ice on the ground don't pull all the way into the bus stop. As you may find yourself stuck trying to get out.

[Via Garibaldi 8]

ENY hit it on the head. The RTSs are older and heavier which is why they have more problems with the kneelers. Give it a couple more years and the O7s will be doing the same thing. I hope MTS has improved the kneelers in the new RTSs....that's the only weakness I think those buses have.

 

Now on the my favorite subject....the MCIs. New or Old they are gonna have problems, it depends on the depot's maintenance. Spring Creek,Yonkers and Eastchester have excellent maintenance so you don't really see a problem. I would be wary about kneeling a College Pt,La Guardia or JFK MCI. I don't know if the shows the B/Os where the leveling valves are in the rear right engine compartment, but knowing how to use them to get the kneeler back up has save my ass a few times.

 

Joel, I'm assuming some buses have that annoying as hell alarm disconnected. When I drove RTSs in CT all of buses had that alarm and magically one by one they got disconnected!

 

Acela, did they tell you NOT to kneel the buses in the winter time? At CTTransit they don't want the guys to kneel the buses during the winter time because all the slush and ice that get thrown up into the wheel wells have a tendency to "freeze" the kneeler down.

 

LOL@ comment in bold.

[Acela Express]

I could do you one better Acela as far as building air pressure back up faster. Engage the parking brake, put the bus in neutral. Then hold the Auxilary Interlock switch and step on the accelerator. Just don't rev the engine too fast it could become quite noisy. And by the way most drivers would tell you not to kneel the bus in the winter time. You would really be delayed using the kneeler. Also when there is snow and ice on the ground don't pull all the way into the bus stop. As you may find yourself stuck trying to get out.

Thanks; I was aware of how to build the air pressure on the RTS', which I've only had to do once when I first started on my own.

 

And about not pulling all the way into the stop, I was advised against it to avoid jumping the curb 'cause of the ice / slippery conditions given. We already got a taste of the snow during that store a few weeks ago; I almost jumped the curb at Empire Blvd. and Utica Ave...

 

SMH!

['89 Liberty MCI]

Though the latest RTS' in our fleet are 12 years old, and they all have kneeling issues when crush loaded, my curiosity now goes for the 99-00 C40s at Jackie Gleason, which don't seem to have any problem with kneeling abilities, unless I'm mistaken?

 

Aside from the heaviness of the RTS, it could also be the build quality, and the fact that the kneeling mechanism on one bus may be easier to maintain than the kneeling mechanism on the other. In those days New Flyer Industries buses had build quality superior to that of Novabus and Orion buses. In KB, 14- and 15-year-old D60HFs continue to have absolutely no problem kneeling whatsoever, while 11- and 12-year-old Orion 05.501 "V"s do have these problems. Novabus has cleaned up its act with the LFS rigid/Artic/LFX though.

 

A side note, which is not really related to the main discussion about different bus types and bus manufacturers, but refers to Artics in general, is that Artics do not make the kneeler work as hard as rigids. For example an Orion V is 40 feet long and weighs 40,000 lbs, while the front 20 feet of the vehicle (or 20,000 lbs I suppose) constitute the part of the bus that gets raised and lowered.

 

A D60HF, on the other hand, is 60 feet long and weights 65,000 lbs. There are two axles in the front section of the bus, which is approximately 35 feet long from the front to the middle of the accordion. But the length of the section is not so much the factor when it comes to the kneeling; the wheelbase from the front axle to the axle nearest the front axle (which would be the middle axle on Artics, which typically have three axles altogether, but the rear wheel on the rigids, which have two axles altogether) is the real factor.

 

This is physics. The D60HF's front wheelbase is 208", which is in fact shorter than even that of the LFS rigid/Artic/LFX (244") and of course shorter than that of the Orion V (280") and RTS. The fulcrum, or pivot point, which keeps the back end of the bus where it is while the front end of the bus rotates about that fulcrum (as short of a vertical distance the front end moves while the kneeler is being used, this does still count as rotation), is the axle/pair of wheels nearest the front axle/pair of wheels.

 

It is true that the LFS Artic and LFX have a longer front wheelbase and possibly a longer front section than the D60HF, but nowadays this is less of an issue due to improved build quality, improved technology and perhaps lower weight due to the use of the low floor rather than the high floor.

 

 

Try to think of the first diagram as analogous to the situation on an Orion V or RTS. The fulcrum, or middle axle, is quite far from the front, where the kneeler is. Because of this relatively large distance (or moment arm or lever arm or torque arm), a large force is required to bring the bus back up. Also only the red arrow (vertical component of the force) causes rotation. The blue arrow (horizontal component) causes no rotation about the fulcrum since it acts along the moment arm.

 

Now try to imagine the second diagram as analogous to the situation on a D60HF. Really any Artic or even a LFS rigid since most Artics and LFS rigids have shorter [front] wheelbases than Orion Vs and RTSs. Now imagine that that force is going up instead of down, since we are trying to keep the situation similar to the first one (kneeler going up rather than down). Due to the relatively small distance, a smaller force is require to bring the bus back up.

 

I got the wheelbases from these links that I found by googling wheelbases:

 

http://www.rideuta.com/files/28-218_1shallowlift.pdf

http://www.novabus.com/documents/Spec_Sheet_FINAL.pdf

Re: 126 & MTV To Swap Routes In 2011 <--Adam Moreira's post

New Flyer Industries D60 - CPTDB Wiki

[East New York]

So what about MCI's? Some B/Os kneel the express bus at every stop, particularly on the Bus routes. I feel like an old man getting on, but it actually does help because the steps can be high esp. if you're stepping on from the street as opposed to the sidewalk. I always worry about them breaking down, but the older ones more so. It has been a problem in the past, where the bus had to be put out of service , but I think the newer MCIs can handle the constant kneeling more.

 

I remember once though my uncle was driving a bus uptown in the city and he had to let some people off and make them walk up the hill and get back on. lol Talk about a ghetto bus. That was the old days though.

 

MCI axles are designed to carry more weight. They have Meritors as well but typically don't kneel as much as transit buses. They also have wide ride suspensions which affect things differently as well.

 

And on LI, why do some of the NGs remain quiet (except for the alarm) when the kneeler is activated but on others they're as loud as an Orion V?

 

Now that I couldn't tell you.

 

ENY hit it on the head. The RTSs are older and heavier which is why they have more problems with the kneelers. Give it a couple more years and the O7s will be doing the same thing. I hope MTS has improved the kneelers in the new RTSs....that's the only weakness I think those buses have.

 

Now on the my favorite subject....the MCIs. New or Old they are gonna have problems, it depends on the depot's maintenance. Spring Creek,Yonkers and Eastchester have excellent maintenance so you don't really see a problem. I would be wary about kneeling a College Pt,La Guardia or JFK MCI. I don't know if the shows the B/Os where the leveling valves are in the rear right engine compartment, but knowing how to use them to get the kneeler back up has save my ass a few times.

 

Joel, I'm assuming some buses have that annoying as hell alarm disconnected. When I drove RTSs in CT all of buses had that alarm and magically one by one they got disconnected!

 

Acela, did they tell you NOT to kneel the buses in the winter time? At CTTransit they don't want the guys to kneel the buses during the winter time because all the slush and ice that get thrown up into the wheel wells have a tendency to "freeze" the kneeler down.

 

Right. A lot of it depends on maintenance and the type of suspension mated to the axle.

 

Aside from the heaviness of the RTS, it could also be the build quality, and the fact that the kneeling mechanism on one bus may be easier to maintain than the kneeling mechanism on the other. In those days New Flyer Industries buses had build quality superior to that of Novabus and Orion buses. In KB, 14- and 15-year-old D60HFs continue to have absolutely no problem kneeling whatsoever, while 11- and 12-year-old Orion 05.501 "V"s do have these problems. Novabus has cleaned up its act with the LFS rigid/Artic/LFX though.

 

A side note, which is not really related to the main discussion about different bus types and bus manufacturers, but refers to Artics in general, is that Artics do not make the kneeler work as hard as rigids. For example an Orion V is 40 feet long and weighs 40,000 lbs, while the front 20 feet of the vehicle (or 20,000 lbs I suppose) constitute the part of the bus that gets raised and lowered.

 

A D60HF, on the other hand, is 60 feet long and weights 65,000 lbs. There are two axles in the front section of the bus, which is approximately 35 feet long from the front to the middle of the accordion. But the length of the section is not so much the factor when it comes to the kneeling; the wheelbase from the front axle to the axle nearest the front axle (which would be the middle axle on Artics, which typically have three axles altogether, but the rear wheel on the rigids, which have two axles altogether) is the real factor.

 

This is physics. The D60HF's front wheelbase is 208", which is in fact shorter than even that of the LFS rigid/Artic/LFX (244") and of course shorter than that of the Orion V (280") and RTS. The fulcrum, or pivot point, which keeps the back end of the bus where it is while the front end of the bus rotates about that fulcrum (as short of a vertical distance the front end moves while the kneeler is being used, this does still count as rotation), is the axle/pair of wheels nearest the front axle/pair of wheels.

 

It is true that the LFS Artic and LFX have a longer front wheelbase and possibly a longer front section than the D60HF, but nowadays this is less of an issue due to improved build quality, improved technology and perhaps lower weight due to the use of the low floor rather than the high floor.

 

 

Try to think of the first diagram as analogous to the situation on an Orion V or RTS. The fulcrum, or middle axle, is quite far from the front, where the kneeler is. Because of this relatively large distance (or moment arm or lever arm or torque arm), a large force is required to bring the bus back up. Also only the red arrow (vertical component of the force) causes rotation. The blue arrow (horizontal component) causes no rotation about the fulcrum since it acts along the moment arm.

 

Now try to imagine the second diagram as analogous to the situation on a D60HF. Really any Artic or even a LFS rigid since most Artics and LFS rigids have shorter [front] wheelbases than Orion Vs and RTSs. Now imagine that that force is going up instead of down, since we are trying to keep the situation similar to the first one (kneeler going up rather than down). Due to the relatively small distance, a smaller force is require to bring the bus back up.

 

I got the wheelbases from these links that I found by googling wheelbases:

 

http://www.rideuta.com/files/28-218_1shallowlift.pdf

http://www.novabus.com/documents/Spec_Sheet_FINAL.pdf

Re: 126 & MTV To Swap Routes In 2011 <--Adam Moreira's post

New Flyer Industries D60 - CPTDB Wiki

 

Well, you have a couple things here. The suspension plays the biggest roll in this. New Flyer has had some of the same problems over the years as well. But again, no standard transit bus is heavier than the RTS. New Flyer also used Meritor axles up until 2007, but decided to go with another company citing ride and build quality issues. True, Nova's build quality on some of the RTS components were definitely off. Yet, you have to remember that vendors contribute directly to the reliability of now OEM parts. And NF's IFS definitely have something to do with how their buses operate. The RTS LF Second gen will likely have IFS similar to that of the DesignLine buses.

 

New Flyers low floors have independent front suspensions IIRC, which also affect things differently as well. Most of it depends on how the suspension is set up in each individual bus.

[20 Dundalk]

Just to add to the topic i have observed the following on all of our buses...

NF C30/35/40/R...TO kNEEL :shift to N set parking brake always loud rush of air as airbags deflate and on all buses an annoying beep beep...alarm to lift the kneel the same alarm

[Acela Express]

Thanks for the input, but that really doesn't add anything to the actual topic, which is the difference between our HF and LF models, which other members chimed in about. It's more of an axle and suspension-related topic during crush loads, actually.

[Via Garibaldi 8]

MCI axles are designed to carry more weight. They have Meritors as well but typically don't kneel as much as transit buses. They also have wide ride suspensions which affect things differently as well.

 

[in Stewie's voice]: Hmm... Interesting. That makes sense. It does seem like even when they kneel you still have to step up a bit to get on. What's funny though is how high it can be getting off. I've had a few times where if I didn't have long legs getting off I probably would've hurt my ankle or fell. LOL That step to get from the bus onto the street can be really high, esp. if they let you out away from the curb. :eek: