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Pumping the Brakes


MHV9218

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If I'm not wrong, all of our fleet has drum brakes, save for a few LFSes to arrive soon.

 

With those LFSes, disc brakes would (I assume) mean you wouldn't need to pump the brakes anymore since brake pressure is not a problem on such disc brakes (as long as we've got ABS).

 

I mention it since pumping the brakes due to brake pressure is INCREDIBLY common on O7s, and it'll be a much different ride without that. I was on 6765 the other day, and the bus was packed. There was a woman standing way in the back, and some idiot opened his door in front of the bus. The B/O started pumping the brakes. Pump 1, she goes about five feet forwards to the steps, Pump 2, she goes to the steps, Pump 3, the poor woman flew right off. Old guy nearby actually had to catch her in the air.

 

With the disc brake LFS (I could have sworn the last 15 had this), that would no longer be a problem, no?

 

The feel of the brakes is slightly different, but they are still air operated, so it isn't that much different. 15 of the new Orion 3G's, and all of the New Flyer Xcelsior's will have disc brakes.

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If I'm not wrong, all of our fleet has drum brakes, save for a few LFSes to arrive soon.

 

With those LFSes, disc brakes would (I assume) mean you wouldn't need to pump the brakes anymore since brake pressure is not a problem on such disc brakes (as long as we've got ABS).

 

I mention it since pumping the brakes due to brake pressure is INCREDIBLY common on O7s, and it'll be a much different ride without that. I was on 6765 the other day, and the bus was packed. There was a woman standing way in the back, and some idiot opened his door in front of the bus. The B/O started pumping the brakes. Pump 1, she goes about five feet forwards to the steps, Pump 2, she goes to the steps, Pump 3, the poor woman flew right off. Old guy nearby actually had to catch her in the air.

 

With the disc brake LFS (I could have sworn the last 15 had this), that would no longer be a problem, no?

 

and almost all of the buses in the fleet (with the exception of some RTS's and Orion V's) have abs...if you've ever been next to or in a bus when it first starts up and you hear those short bursts of air before the engine actually starts, thats the abs booting up and doing a self diagnostic...

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and almost all of the buses in the fleet (with the exception of some RTS's and Orion V's) have abs...if you've ever been next to or in a bus when it first starts up and you hear those short bursts or air before the engine actually starts, thats the abs booting up and doing a self diagnostic...

 

I've been wondering for the longest what that tisk tisk noise was before some buses started up... now I know!

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all of the LFSA's have disc brakes and they take a lot longer to stop than drum brakes so the bus would have just taken the door off than stopped

 

That's strange.....in my company's fleet, our early model MCI J4500's have drums, and the later model have discs. The disc brake models stop much better than the drums...you don't have to use nearly as much pressure on the treadle to stop. Both types are ABS in our fleet.

 

As far as "pumping" the brakes....that technique does not stop the bus any faster, in fact it only wastes air pressure, and gives the passengers a 'jerky' ride. It should only be used in a 'panic stop' on a non-ABS bus on a slick road to prevent the brakes from locking up and causing a skid.

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Why have buses generally been equipped with drums?

 

drum brakes work better than disc brakes, especially for heavier applications. disc brakes are only becoming popular b/c their are less things to effect the stopping power of the brakes. with drum brakes, if the shoes get wet, over heat/glaze over, or come in contact with with grease (from s/o inspection) the stopping power is significantly decreased. disc brakes don't really have most of those problems other than occasional over heating in emergency situations...

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That's strange.....in my company's fleet, our early model MCI J4500's have drums, and the later model have discs. The disc brake models stop much better than the drums...you don't have to use nearly as much pressure on the treadle to stop. Both types are ABS in our fleet.

 

As far as "pumping" the brakes....that technique does not stop the bus any faster, in fact it only wastes air pressure, and gives the passengers a 'jerky' ride. It should only be used in a 'panic stop' on a non-ABS bus on a slick road to prevent the brakes from locking up and causing a skid.

 

I too was under the impression that disc brakes were better, and this was one of the reasons New Flyer will discontinue use of the S-Cam drums when the LFR's are discontinued......

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I too was under the impression that disc brakes were better, and this was one of the reasons New Flyer will discontinue use of the S-Cam drums when the LFR's are discontinued......

 

most bus manufacturers are switching over to discs b/c they are looking at the big picture from a safety point of view. all the things i mentioned before can equal brake failure and possibly cause a crash. disc brakes don't work as well, but are not as effected by the factors in my previous post...

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most bus manufacturers are switching over to discs b/c they are looking at the big picture from a safety point of view. all the things i mentioned before can equal brake failure and possibly cause a crash. disc brakes don't work as well, but are not as effected by the factors in my previous post...

 

Makes sense. I personally have never driven a bus with disc's, so I wouldn't know how they feel to compare them myself.

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and almost all of the buses in the fleet (with the exception of some RTS's and Orion V's) have abs...if you've ever been next to or in a bus when it first starts up and you hear those short bursts of air before the engine actually starts, thats the abs booting up and doing a self diagnostic...

 

I remember there was a sound right before some 1993-1996 Orion V's(not sure about 1999's) it was LOUD. Its like VOOOOWW.

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