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Author Topic: speed governor- (not wife)  (Read 2255 times)
ttomas
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« on: August 23, 2007, 04:11:12 PM »

Is there a speed governor in addition to a rpm governor on a  mc9- 6v92ta / 740 trans? If so, can I adjust it to go faster down hill?  Thanks Tomas
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Hartley
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« Reply #1 on: August 23, 2007, 05:29:02 PM »

Yeah, It's that stream of parts following you down the hill when you overwind the engine.

You really don't want to overrev a detroit too much. they degrade rapidly above 2,400 rpm and start breaking down internally and will eventually lose seals, sleeves and other parts. They can't run at 5,000 rpm like your honda.....

Seriously... Having 30,000 lbs of out of control bus screaming down a hill just scares the jeebers outta me... I almost had that happen a couple of months ago... Lucky I have a Jersey 9 with better brakes!!!

Dave..... Want real fun, Try Hwy I27 across Signal Mountain Tennessee... Parachutes Optional!!
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Dallas
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« Reply #2 on: August 23, 2007, 05:36:53 PM »

As you reach the top of the hill, close your eyes, put the bus in Georgia Overdrive, hang on and GO!

Just make sure I'm no where around when you do it.

Dallas
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RJ
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« Reply #3 on: August 23, 2007, 06:10:31 PM »

Is there a speed governor in addition to a rpm governor on a  mc9- 6v92ta / 740 trans? If so, can I adjust it to go faster down hill?  Thanks Tomas

Why???
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RJ Long
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« Reply #4 on: August 23, 2007, 07:22:02 PM »

Is there a speed governor in addition to a rpm governor on a  mc9- 6v92ta / 740 trans? If so, can I adjust it to go faster down hill?  Thanks Tomas

Why???

That's simple Russ! To be the first one down the hill! LOL! Grin  BK  Grin
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« Reply #5 on: August 23, 2007, 07:51:03 PM »

BK -

You mean to be the first one at the accident site, right?

 Shocked
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RJ Long
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ttomas
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« Reply #6 on: August 23, 2007, 08:09:04 PM »

thanks guys, I knew I was going to catch it from you. 74 mph is definitely fast enough. that is my downhill top end. I have trouble topping  the next hill at 35. my last 210 hp cummins school bus did way better. Is this normal?  Tomas
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Dallas
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« Reply #7 on: August 24, 2007, 04:36:25 AM »

Tomas,

Considering that your MC9 weighs 15,000 pounds more than your skoolie, that's not too bad. Your 6V92TA can be turned up to put out more torque and HP (350?) if it's still in the factory configuration.
The only thing going downhill faster will get you is a ride in a helicopter.... to the hospital... if you survive.

There are also other things you can do to help get up the hill faster.
When was the last time you checked the air intake?
Air Filter?
Do you manually downshift your HT740 before you start dropping RPM's? If you are blowing smoke as you go up the hill, your wasting fuel and horse power. Keep the RPM's up in the power range. Don't let the transmission decide when to shift... it's kind of stupid and doesn't really care what the engine says.
When was the last time the rack was run in that engine?

Good luck and if you decide to drop off Cabbage, Snowbird, Grapevine, Lolo, Pipestone, Monteagle or any other big hills in neutral, let me know ahead of time so I can wake up Cat.
I want to wake her up 'cause she ain't never seen a wreck like this ones gonna be! Roll Eyes

Dallas
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ttomas
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« Reply #8 on: August 24, 2007, 06:06:36 AM »

Thanks Dallas,  I was not aware that I should override the auto shift.that should help. I have only driven the bus 800 miles, and that was when I bought it. I changed  all filters when I got home. This helped. Yestereday I found a clogged up Catalytic converter. This was probably my problem. My 40' Thomas bus weighed in at 30,500lbs.. Hopefully the mc9 is not 45k
thanks for the picture. point well taken. tomas
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maria-n-skip
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« Reply #9 on: August 24, 2007, 07:02:32 AM »

Dallas,

   Nice blast from the past. Was the pic taken in the early 50's?

    Lolo, Pipestone....If you were referring to the Montana ones we have worse
 and so does the rest of the rocky mountain range.  For those of you liking to travel state
 higways instead of  Interstate please be careful at 30k+lbs speeds build up fast and when the sign
 says curve 35mph I always make sure I'm at 25mph. Not so many white knuckles
 when done. Speed limits are mostly set for the normal vehicle not heavies it is assumed
 that heavies are driven by professionals and they should know the value of keeping their speed
 safe and reasonable.
   FWIW
  Skip
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H3Jim
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« Reply #10 on: August 24, 2007, 07:50:49 AM »

In the bus I have found that I can comfortably take most corners at the posted speed.  Thats without shifting things on my shelves, or doing any uncomfortable leaning.

When I was younger and in a car I found that could take most corners at almost twice the posted speed.  Hope there's not more like me out there.
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Jim Stewart
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Dallas
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« Reply #11 on: August 24, 2007, 08:12:51 AM »

Dallas,

   Nice blast from the past. Was the pic taken in the early 50's?

    Lolo, Pipestone....If you were referring to the Montana ones we have worse
 and so does the rest of the rocky mountain range.  For those of you liking to travel state
 higways instead of  Interstate please be careful at 30k+lbs speeds build up fast and when the sign
 says curve 35mph I always make sure I'm at 25mph. Not so many white knuckles
 when done. Speed limits are mostly set for the normal vehicle not heavies it is assumed
 that heavies are driven by professionals and they should know the value of keeping their speed
 safe and reasonable.
   FWIW
  Skip


Skip,

The picture is from 1948 and use to be a school bus. I forget what kind.

Yes, I was talking about Montana, Idaho, California, Oregon and Idaho. Those were the places I was mostly raised in. We had a logging company when I was young and I learned to drive on a 1941 A-40 model Mack with a flathead 6 cylinder engine, single axle, air over hydraulic brakes, a 4 speed main transmission, 3 speed aux. and a 3 speed truck transmission turned backwards to give us granny-granny-low-low. We needed it since we pulled log trailers with 60K pounds of lodge pole pine down the same roads the guys with the BIG trucks used.
I felt like one of the big boys when my step dad bought a 1963 needle nosed KW with a 250 cummins and a 5X4 two stick transmission.

Dallas
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maria-n-skip
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« Reply #12 on: August 24, 2007, 08:31:41 AM »


 Jim & Dallas,

   Both you old boys know this part of the country well and have the experience to back it.
You would be surprised on the number of Flat landers (no disrespect intended)
 I see hitting the brakes at the apex of a curve coming down a pass. Knowing a road and experience in the rig
 gives one a lot of latitude at what speeds one goes down a pass.


 Skip
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HB of CJ
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« Reply #13 on: August 24, 2007, 01:45:08 PM »

Sounds like (maybe?) you have a mechanical Detroit, along with the earlier 740.  But then again maybe not.  Going down a hill very fast would overwhelm any governor, speed limiter or engine brake.

Gravity really sucks really.  You would reach a point where it would be practically impossible to stop the coach in a reasonable fashion, except to decelerate really fast and hard hitting a mountain.

The Grapevine is not a pussycat.  Many times I went North and South, first with a now old , newer then Crown school bus full of kids, then later hauling product (gas) from Bakersfield to Terminal Island.

Coming down empty North with the school bus, the old girl would hang right at 40-45 mph riding the Jake all the way down.  With the tanker full of gas, right at 18 to 20 mph both ways, again on the Jake,...

...with regular service brake applications.  Do remember once a "runaway" came flying past North with flames coming from the tires and wheels.  It crashed rather badly.  Guess the tires finally exploded.

An ongoing problem seems to be ordinary folks buying these huge nice motorcoaches and still thinking  they can drive the beasts just like their cars.  Bad idea.  Life is too short. Thanks. Smiley Smiley
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DrivingMissLazy
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« Reply #14 on: August 24, 2007, 02:24:36 PM »

I recall a poster recently (who shall go unnamed) that was apparently not knowledgeable about the requirement to gear down when coming down long grades. He got somewhat indignant when it was suggested he go to northern California a get Russ to give some driving lessons on a bus. LOL
Richard
 

Sounds like (maybe?) you have a mechanical Detroit, along with the earlier 740.  But then again maybe not.  Going down a hill very fast would overwhelm any governor, speed limiter or engine brake.

Gravity really sucks really.  You would reach a point where it would be practically impossible to stop the coach in a reasonable fashion, except to decelerate really fast and hard hitting a mountain.

The Grapevine is not a pussycat.  Many times I went North and South, first with a now old , newer then Crown school bus full of kids, then later hauling product (gas) from Bakersfield to Terminal Island.

Coming down empty North with the school bus, the old girl would hang right at 40-45 mph riding the Jake all the way down.  With the tanker full of gas, right at 18 to 20 mph both ways, again on the Jake,...

...with regular service brake applications.  Do remember once a "runaway" came flying past North with flames coming from the tires and wheels.  It crashed rather badly.  Guess the tires finally exploded.

An ongoing problem seems to be ordinary folks buying these huge nice motorcoaches and still thinking  they can drive the beasts just like their cars.  Bad idea.  Life is too short. Thanks. Smiley Smiley
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ttomas
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« Reply #15 on: August 24, 2007, 07:25:19 PM »

No one but several of you folks said anything about recklessly flying down mountains.I asked a mechanical question and got blasted. I tried to humbly get out of it but I see that did not work.
I am the slowest vehicle descending all steep grades not a reckless fool as many of you suggest.
How many of you do not accelerate at the bottom of a hill to gain advantage on the next?

I  frequently visit this site and appreciate it because of the years of knowledge and experience it offers. Although I got some well intentioned and good advice ,both mechanical and other,several of you are out of line. Tomas
     


   
   
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maria-n-skip
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« Reply #16 on: August 24, 2007, 07:52:05 PM »

 Sorry

    It was not my intention to blast you. More my own sop box
 for people to be safe.

   

   Skip
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Dallas
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« Reply #17 on: August 24, 2007, 08:12:08 PM »

Chill out ttomas,

We have all been trying to tell you in humorous and other ways, what you are proposing is dangerous and deadly.

Whether you drive slow down the hill or not, if you aren't in control of your vehicle, you are a danger to yourself and others.

With the question you asked, you let it be known that you weren't conversant with the whys and wherefores of downhill speed limits for heavy vehicles.

Question... Why do you need to top the hill at 70 instead of 35 anyway? is another few seconds going to make that much difference in the overall length of your trip?

About 20 years ago while I was driving for a flat bed company out of Fargo, ND. the boss asked 8 of us to try a test. He offered to turn 4 of the trucks up to maximum rpm and power (3406 and 3176 Cat engines), and turn the other 4 down to 58 mph.
Since he was paying the bills, and offered all of us a bonus for the test, we took him up on it. My truck was turned up to 81mph.
A friends truck was turned down.
We both ran identical loads from Bucyrus, Oh to Fresno, Ca.
I ran fast and hard, always a few hours of my log book and burning fuel at a furious rate. I could climb hills at just about any speed I wanted.
My friend, governed at 58mph ran his log book legally, climbed hills at 25 to 35 mphbut got almost 2mpg  better than I did.
He arrived in Fresno 4 hours and 15 minutes after I did, but got unloaded within ten minutes of me. He also was rested, ready to roll and still had hours left to play with.
For a distance 2450 miles, 4 hours isn't that much difference.
The moral here I leave up to you.

No your question was not stupid, none of them on this board are, but it does go to show that more education is needed by many newbies who want to run like a car or SUV. These vehicles are NOT either one.

Dallas
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ttomas
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« Reply #18 on: August 24, 2007, 08:31:28 PM »

 
   You folks went on  about recklessly  flying down mountains, killing people and such. I asked a mechanical question and got blasted.
I tried to humbly get out of it but that did not work. I am among the slowest vehicle to descend steep grades.  How many of you do not accelerate at the bottom of a hill to gain advantage on the next?
   I frequently view this site because of the knowledge and experience to be gained. Some gave good advice mechanically and otherwise to my question, most were out of line. The question about one or two governors was never answered. Tomas
   
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ttomas
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« Reply #19 on: August 24, 2007, 08:33:12 PM »

I thought my last post was not posted. Thanks guys
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maria-n-skip
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« Reply #20 on: August 24, 2007, 08:42:44 PM »

There are two govenors.
 One for RPM and one for trans shifting. (for 99% of aplications)
 If you have a a computer controlled engine there is a top speed control
 but I doubt you would go that fast. 74 is not it. Some of the guys
 with the high tech engines could probably tell you what that is.

Skip
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belfert
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« Reply #21 on: August 24, 2007, 09:02:21 PM »

My Series 60 with DDEC III had the speed governer electronically set at 68 MPH.  I think I had Detroit disable the speed governer, or at least turned it up.  I don't intend to ever drive beyond 70 or 71 MPH, but I want to decide, not the computer.

Sorry, I know nothing about speed governers on mechanical engines.  If you have a DDEC, there may be a electronic governer like I have.
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