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Author Topic: Air Throttle  (Read 1945 times)
Dreamscape
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« on: November 05, 2006, 06:28:01 AM »

Good Morning Bus Nuts,

While I am waiting for the sun to come up so I can tackle the post on the alternator problem I thought I would ask for some help on this subject.

I am thinking of installing an air throttle on our Eagle. The linkage is very worn out and the response time is not great.

Has anyone installed one? What were the results? What were the pitfalls?

Could not find much information on any threads.

Paul
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DrivingMissLazy
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« Reply #1 on: November 05, 2006, 09:51:38 AM »

If you have an automatic tranny they are great. I know, I had one. If it is manual, I understand that the air throttle is a pain and is difficult to control the throttle precisely enough when double clutching.
Richard
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Life should NOT be a journey to the grave with the intention of arriving safely in an attractive and well preserved body. But rather to skid in sideways, chocolate in one hand, a good Reisling in the other, body thoroughly used up, totally worn out and screaming:  WOO HOO, what a ride
Dreamscape
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« Reply #2 on: November 05, 2006, 10:28:56 AM »

I have the four speed crash box, so I guess I will have to put up with rebuilding the linkage somewhere down the road.

Thanks,

Paul
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Stan
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« Reply #3 on: November 05, 2006, 11:47:35 AM »

If you are going to stay with a mechanical throttle system, I would suggest you go to a Morse cable.
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TomC
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« Reply #4 on: November 05, 2006, 06:25:20 PM »

You can use an air throttle with manual, it just takes a little bit to get used to the slight delay of the air.  Personnally, would change since the pedal pressure is light and it is very reliable.  Only down side, you can't throttle with no air pressure.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Dreamscape
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« Reply #5 on: November 06, 2006, 05:37:05 AM »

Cable sounds interesting. I just would like to DO IT RIGHT THE FIRST TIME. The only thing regarding cable is they break, and with a long run it might not be the best. I do not have first hand knowledge on that, regarding buses that is. Just an thought.
I'm just looking for a faster response. I am not worried about the air pressure as we will have an on board small air compressor if need be.
I will keep scaning the responses here.

Thanks,

Paul
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RJ
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« Reply #6 on: November 06, 2006, 07:07:11 AM »

Paul -

The most severe revenue service any bus is subjected to is that of the transit.  Drive a block, stop.  Drive a block, stop.  Every day, 12 to 18 hours per day.

For nearly 40 years, up until the electronic "drive-by-wire" engines, transits used air throttles.  What does that tell you?

Back when I worked in the charter bus industry, we had several GMC 4905s with (optional) air throttles and 4-spd Spicers.  As TomC said, they take some getting used to, but no worse than the wet clutch those buses had.  Air throttles respond slightly differently, and can cause some gear crunching until you figure them out.  No big deal, really, and they're certainly less fatiguing to drive on a long run than a worn cable/mechanical linkage.

Most common failure of an air throttle is the diaphragm on the engine side.  Carry a spare, replacement takes about 10 minutes.

OTOH, GMC used Morse-type cables on all their highway models for years.  Secret was keeping them lubed properly.  Usually the cable itself never broke, but sometimes the cable's housing would, especially in the rear axle area.  90% of the time, the breakage was due to poor maintenance (lack of lubrication), the other 10% was due to corrosion issues.

Your choice - do it your way!

FWIW & HTH. . .

 Wink
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Stan
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« Reply #7 on: November 06, 2006, 08:36:59 AM »

Russ has it right about GM using morse type cables on their buses. If you go through the archives you will find people who have to pull out the inside cable and do a clean and lubricate job. Since this is after fifty years of service it is not surprising. If you get a genuine Morse cable recommended for the application it will outlast you, and probably outlast the bus.

It is just as easy to pull in a flexible cable as an air line (both about the same size) and it gives you positive control of the governor. A cable has very little drag and doesn't require the heavy pull-back spring that the rod linkage has. If you use a mechanical type of cruise control it is easier to adapt to a mechanical system. I have used all three types and prefer the cable. Your mileage may vary!
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Dreamscape
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« Reply #8 on: November 08, 2006, 05:01:15 PM »

Russ and Stan,

Thank You for the valuable information.

I think the Morse cable might be just the ticket. Any idea where to purchase one for our Eagle?

Thanks,

Paul
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Stan
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« Reply #9 on: November 08, 2006, 05:36:56 PM »

Most industrial supply houses that sell bearings and all the assorted parts that are used in drive systems (belts, pulleys, gear boxes etc.) also handle Morse cables. There may be other manufacurers that make a similar and equal product but Morse has been in the business so long that their name is almost generic.

You need to know the length you need before you order. They come in a large number of standard lengths and just make sure you get one that is long enough. They don't stretch but you can 'S' curve them to take up excess length. You can also order a custom length but special orders cost more. A supplier will have all the information to select the proper type once you know the length.

Try this link to Teleflex Morse to find a distributor near you

http://www.teleflexmorse.comhttp://www.teleflexmorse.com/Distributors.html/Distributors.html
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FloridaCliff
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« Reply #10 on: November 08, 2006, 05:38:05 PM »

Paul,

I have an air throttle with my four speed.

No problem.  As a matter of fact I straight shift every gear(no double clutch)...unless I miss it Cool

As others have said its just a matter of feel.

Cliff
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1975 GMC  P8M4905A-1160    North Central Florida

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