Quick question from the wife...

Sebulba · August 12, 2021, 08:40:57 PM

Quote from: RJ on August 11, 2021, 11:09:39 PM
Seb -

The DOT test is referenced here near the bottom:

http://busnut.com/forum/index.php/topic,3259.0.html

Every bus owner should follow this checklist (or one that they've added their own checks to be done over and above this generic list) before moving their coach for the first time every day. Professional drivers have to do it as it's required by law. Just because private owners aren't, doesn't mean they shouldn't.

It's pretty obvious in a campground watching Class A diesel pusher owners who simply start the engine and drive off that they're completely clueless about a thorough pre-trip inspection - especially the air brake check.

One of my pet peeves. . . but the political pressure to not require a pre-trip for private owners overwhelms any efforts to reverse that mindset.

FWIW & HTH. . .

Very good advice. I'm a pilot, so way ahead of you on the checklist idea.

Thanks

Seb

DoubleEagle · August 13, 2021, 06:19:57 AM

Another factor in air supply is the output of the air compressor itself. Bendix makes many levels of compressors. One vehicle might have a Tu-Flo 400 with 7.25 CFM, or a Tu-Flo 500 with 12 CFM. My Series 60 had a Tu-Flo 550 with 13.2 CFM, but when I replaced it I put in a 750 with 16.5 CFM. A higher output compressor can overcome leaks and high usage better, and a tired compressor might not be putting out to specs.

buswarrior · August 13, 2021, 06:46:11 AM

Re: ugrading to a bigger compressor.

In the hybrid transit bus field, the buses had a smaller engine to spin the generator, an engine that would have been in a smaller truck, than in a full size transit bus...

These Cummins drive the compressor off a row that includes the fuel pump... anyway, the biggest compressor that this geartrain could handle, was not sufficient for transit bus duty, ran continuously, and couldn't be upgraded without putting the combined drive in jeopardy.

Be sure that the guts can reliably drive the desired compressor.

More air is lovely, if you can get it!

Happy coaching!
Buswarrior

dtcerrato · August 13, 2021, 08:01:42 AM

BW wisely put...

Sebulba · August 13, 2021, 08:26:34 AM

Quote from: DoubleEagle on August 13, 2021, 06:19:57 AM
Another factor in air supply is the output of the air compressor itself. Bendix makes many levels of compressors. One vehicle might have a Tu-Flo 400 with 7.25 CFM, or a Tu-Flo 500 with 12 CFM. My Series 60 had a Tu-Flo 550 with 13.2 CFM, but when I replaced it I put in a 750 with 16.5 CFM. A higher output compressor can overcome leaks and high usage better, and a tired compressor might not be putting out to specs.

Wow! I had no idea. I suppose the different compressors would be for different uses for the bus.

I Iove this board and the amazing wealth of knowledge here.

Thanks

Sed

DoubleEagle · August 13, 2021, 08:54:17 AM

Quote from: buswarrior on August 13, 2021, 06:46:11 AM

Be sure that the guts can reliably drive the desired compressor.

Happy coaching!
Buswarrior

If the coach A/C is no longer in use, a lot of engine capacity is freed up. In the case of a Series 60, it has enough torque even with A/C. Going from a 550 to a 750 is a 25% increase in capacity. How much more torque is required is an unknown.

buswarrior · August 13, 2021, 09:03:17 AM

Quote from: DoubleEagle on August 13, 2021, 08:54:17 AM
If the coach A/C is no longer in use, a lot of engine capacity is freed up. In the case of a Series 60, it has enough torque even with A/C. Going from a 550 to a 750 is a 25% increase in capacity. How much more torque is required is an unknown.

It wasn't engine power that limited these, the gear train for the accesories was already at its rated max, being designed for a medium duty role, not a heavy duty one.

Putting a bigger compressor would have broken the gear train, or the coupler between it and the fuel pump, etc.

The schoolie crowd would be in the same boat, same limitations to an upgrade.

Happy coaching!
Buswarrior

DoubleEagle · August 13, 2021, 04:04:01 PM

That may be the case for some engines, which ones are you referring to? The Tu-Flo 750 is an option for the 12.7L Series 60, and the gear train is handling it just fine.

Sebulba · August 13, 2021, 10:29:47 PM

Quote from: DoubleEagle on August 13, 2021, 04:04:01 PM
That may be the case for some engines, which ones are you referring to? The Tu-Flo 750 is an option for the 12.7L Series 60, and the gear train is handling it just fine.

The bus I was asking this question in reference to has an 8v92. The only engines I'm really considering are the 8v92, 6v92 or the 60 series.

Seb

buswarrior · August 14, 2021, 04:26:22 AM

MEDIUM DUTY engines may have this limitation, particularly the Cummins, which drive the compressor ganged in a line off the fuel pump, perhaps others?

NOT the usual engines found in a motorcoach. NOT NOT NOT

$hit, this is how the newbies get all f'd up...

Busnut myth # 13-45 has now been started...

Happy coaching!
Buswarrior