Semi/Truck Performance

[Jahee]

Originally posted by: skyking
You shift a truck or any manual without the clutch by rev matching. It is easier on a truck because of the smaller RPM range.
A typical truck engine tops out at 2100 RPM, and you work it from 1500~1900.
A car has a much wider range, faster throttle response and is a bit trickier to rev match.
I never use the clutch on a truck after I get rolling. My clutch leg would fall off, LOL! The springs on those things are humoungus.

I thought it'd be something like that yea... is that not bad for the box after time though? i've never understood how you change gears in a truck, i mean you can't have the normal H pattern stick, what do you have? is it digital or what?

 

[Thorny]

Originally posted by: novasatori
i saw a fire dept water pumper (a large one) booking it down the highway at over 120+mph

Was it old or new? When I was on the dept, ours cut out at 64mph.

Edit: I've never heard of a pumper that wasn't limited. A converted tanker maybe, but not a pumper.

 

[Jahee]

Originally posted by: Thorny

Originally posted by: novasatori
i saw a fire dept water pumper (a large one) booking it down the highway at over 120+mph

Was it old or new? When I was on the dept, ours cut out at 64mph.

Edit: I've never heard of a pumper that wasn't limited. A converted tanker maybe, but not a pumper.

Why were they limited? do things start to get hairy past that speed or?? If its an emergency response then the drivers are likely to be trained to drive at speed?

 

[fatpat268]

Originally posted by: compman25
You guys must mean when a Swift truck tries to pass a Schnieder truck!!!!! Only it's more like 65.000000001 trying to pass 65.0000000000001 mph. They are asses doing that, especially when they start the pass at the base of a hill.

I thought schneider was limited to 63...

At least, that's what my dad said a while ago, I dunno if they upped the limit

 

[Eos]

Originally posted by: I Saw OJ

Originally posted by: Allanv
500 BHP for some

8 miles to the gallon

without the trailer starting in 6th gear 0 - 60 in 6 seconds, if you can keep it straight <

with loaded trailer 0 - 60 in 4 weeks

But i am glad i dont drive them anymore

8mpg? Thats not bad at all, I thought they got along the lines of 2-3

With two 150 gallon tanks, you would almost never run far enough empty to get a good idea of what the empty mpg is like. Although I did run empty from Denver Internatinal to Marshalltowqn, IA (about 700 miles) to pick up a load. That was good mpg. I ran a light one from Columbus, OH to San Francisco in the summer. It was only 45k total weight including truck and load, so I got around 7, but this again included idling the truck at night for A/C and electrical power. 4 nights to get from OH to CA.

 

[Demon-Xanth]

One thing to note is that the engines in those rigs vary alot. There are some flat land trucks that have reletively small engines that when they encounter a grade slow to 25MPH and others that fly up the same grade at 60. I lived in the Sierra Nevada foot hills most of my life, and you could tell when a truck was going to have a very long day.

 

[Eos]

Originally posted by: Jahee

Originally posted by: skyking
You shift a truck or any manual without the clutch by rev matching. It is easier on a truck because of the smaller RPM range.
A typical truck engine tops out at 2100 RPM, and you work it from 1500~1900.
A car has a much wider range, faster throttle response and is a bit trickier to rev match.
I never use the clutch on a truck after I get rolling. My clutch leg would fall off, LOL! The springs on those things are humoungus.

I thought it'd be something like that yea... is that not bad for the box after time though? i've never understood how you change gears in a truck, i mean you can't have the normal H pattern stick, what do you have? is it digital or what?

A lot of drivers say not using the clutch is bad for a truck, although most large fleets don't keep tractors for more than 3 or 4 years, then sell them. I would guess that 80% of drivers or more never use a clutch except when starting from a complete stop. I would lope along in 2nd or 3rd in heavy traffic letting gaps be created in front me (then they disappear as traffic slowed down) just so I wouldn't have to completely stop. By holding a steady speed in traffic, everyone would have an easier time, btw.

 

[Demon-Xanth]

For reference:
A Peterbilt 379 is available with six different engines with HPs ranging from 305 to 600HP

 

[DivideBYZero]

This is a really interesting thread. :thumbsup:

Keep the posts from current and former truckers up. Good stuff.

 

[novasatori]

Originally posted by: Thorny

Originally posted by: novasatori
i saw a fire dept water pumper (a large one) booking it down the highway at over 120+mph

Was it old or new? When I was on the dept, ours cut out at 64mph.

Edit: I've never heard of a pumper that wasn't limited. A converted tanker maybe, but not a pumper.

Hmm, It may not have been a pumper, it looked like one, I don't remember a ladder.

It was new looking but this was of course about 5-6 years ago. I remember it well because I was driving and then it went flying by me and I topped out the car I was in @ 120 and it was still pulling away. I was like WTF

 

[Thorny]

Originally posted by: Jahee

Originally posted by: Thorny

Originally posted by: novasatori
i saw a fire dept water pumper (a large one) booking it down the highway at over 120+mph

Was it old or new? When I was on the dept, ours cut out at 64mph.

Edit: I've never heard of a pumper that wasn't limited. A converted tanker maybe, but not a pumper.

Why were they limited? do things start to get hairy past that speed or?? If its an emergency response then the drivers are likely to be trained to drive at speed?

Those things are as graceful as an 8 year old girl carrying 2 five gallon buckets of water. When you've got 1500 gallons of water, you don't stop or turn fast. They have plenty of power to get to those speeds, but they are lacking in suspension, brakes and tires to handle it. Not to mention the wind speeds of 120mph would likely toss all your hose right off the truck. Driving one is like riding on a jackhammer too. Just riding down the highway can cause your can of coke to overflow if its more than half full.

I imagine insurance prolly has something to do with it too. Ambulance's and police can speed to help peolpe if need be, fire trucks have no business going that fast.

 

[PAB]

Originally posted by: I Saw OJ

Originally posted by: Allanv
500 BHP for some

8 miles to the gallon

without the trailer starting in 6th gear 0 - 60 in 6 seconds, if you can keep it straight <

with loaded trailer 0 - 60 in 4 weeks

But i am glad i dont drive them anymore

8mpg? Thats not bad at all, I thought they got along the lines of 2-3

8 is EXTREMELY high for the industry. If you average 8MPG, loaded you're at the top of the class.

A more realistic number is closer to 6.

 

[Eos]

Originally posted by: PAB

Originally posted by: I Saw OJ

Originally posted by: Allanv
500 BHP for some

8 miles to the gallon

without the trailer starting in 6th gear 0 - 60 in 6 seconds, if you can keep it straight <

with loaded trailer 0 - 60 in 4 weeks

But i am glad i dont drive them anymore

8mpg? Thats not bad at all, I thought they got along the lines of 2-3

8 is EXTREMELY high for the industry. If you average 8MPG, loaded you're at the top of the class.

A more realistic number is closer to 6.

Confirmed.

EDIT:

I've gotten as bad as 4 mpg in a day cab truck running 105,500 pounds gross in mostly flat lands, to as high as 7+ mpg in an over the road truck with super light (under 15k net, 50k gross) weight loads.

 

[Jahee]

Originally posted by: Thorny

Those things are as graceful as an 8 year old girl carrying 2 five gallon buckets of water. When you've got 1500 gallons of water, you don't stop or turn fast. They have plenty of power to get to those speeds, but they are lacking in suspension, brakes and tires to handle it. Not to mention the wind speeds of 120mph would likely toss all your hose right off the truck. Driving one is like riding on a jackhammer too. Just riding down the highway can cause your can of coke to overflow if its more than half full.

Lol, i like the analogy

Do you mean because the suspension is set up hard to help with handling, or because they are so sloppy and lumbering that the coke is spilt?

 

[Jahee]

Originally posted by: eos
It was only 45k total weight including truck and load, so I got around 7, but this again included idling the truck at night for A/C and electrical power. 4 nights to get from OH to CA.

Is that x1000 pounds ur using or kilos?


Alot of truck drivers on this forum!



Does anyone hav an explanation for this?:

Originally posted by: Jahee

I remember seeing once, i was driving next to a truck carrying about 20 tons of rubble, this is doing about 70... conditions were pretty bad, and we kind of went over a small crest, and i remember looking over at the truck to see how the suspension handled it, and the front wheel on my side was literally bouncing up and down REALLY quick coming a good few inches off the ground with each 'bounce' , i dont know if the wet had anything to do with it but that was scary, needless to say i quickly got away from it, i wonder what caused it...

 

[skyking]

front wheel on my side was literally bouncing up and down REALLY quick coming a good few inches off the ground with each 'bounce'

out of balance and/or out of round, combined with the washboard of a well-worn road.

i mean you can't have the normal H pattern stick, what do you have?

PDF link for road ranger 13 speed.

 

[Jahee]

Originally posted by: skyking

front wheel on my side was literally bouncing up and down REALLY quick coming a good few inches off the ground with each 'bounce'

out of balance and or out of round, combined with the washboard of a well-worn road.

Ohh ok, note that it didnt happen the entire time, just for a few seconds then stopped, still the same problem, it was pretty shocking!

 

[Eos]

Originally posted by: Jahee

Originally posted by: eos
It was only 45k total weight including truck and load, so I got around 7, but this again included idling the truck at night for A/C and electrical power. 4 nights to get from OH to CA.

Is that x1000 pounds ur using or kilos?


Alot of truck drivers on this forum!



Does anyone hav an explanation for this?:

Originally posted by: Jahee

I remember seeing once, i was driving next to a truck carrying about 20 tons of rubble, this is doing about 70... conditions were pretty bad, and we kind of went over a small crest, and i remember looking over at the truck to see how the suspension handled it, and the front wheel on my side was literally bouncing up and down REALLY quick coming a good few inches off the ground with each 'bounce' , i dont know if the wet had anything to do with it but that was scary, needless to say i quickly got away from it, i wonder what caused it...

Should have specified; 45,000 pounds. As for the bouncing suspension, I've never been explained why that happens.

 

[Jahee]

No problem thanks for clearing it up

Is that a regular occurence on trucks then?

 

[skyking]

When the lane gets worn, it can be bad. You'll sometimes see a truck in the second lane because it is so bad in lane 1.

 

[Jahee]

Originally posted by: skyking
When the lane gets worn, it can be bad. You'll sometimes see a truck in the second lane because it is so bad in lane 1.

So its common? and on a perfectly balanced and rounded wheel it shouldn't happen...?

What does it feel like to the driver? just alot of shock to the steering wheel as in say... driving over cobbles? or a rumble strip?

 

[Eos]

Originally posted by: Jahee

Originally posted by: skyking
When the lane gets worn, it can be bad. You'll sometimes see a truck in the second lane because it is so bad in lane 1.

So its common? and on a perfectly balanced and rounded wheel it shouldn't happen...?

What does it feel like to the driver? just alot of shock to the steering wheel as in say... driving over cobbles? or a rumble strip?

This country is littered with interstates in horrible condition. I think the only interstate I have not driven on is I-8 and maybe a couple other. And they all have bad sections. Some run for miles in bad shape.

 

[Thorny]

Originally posted by: Jahee

Originally posted by: Thorny

Those things are as graceful as an 8 year old girl carrying 2 five gallon buckets of water. When you've got 1500 gallons of water, you don't stop or turn fast. They have plenty of power to get to those speeds, but they are lacking in suspension, brakes and tires to handle it. Not to mention the wind speeds of 120mph would likely toss all your hose right off the truck. Driving one is like riding on a jackhammer too. Just riding down the highway can cause your can of coke to overflow if its more than half full.

Lol, i like the analogy

Do you mean because the suspension is set up hard to help with handling, or because they are so sloppy and lumbering that the coke is spilt?

The coke overflows from the vibration and bouncy ride, it literally shakes the fizz out of it. The ride is rough because the trucks are so heavy and built to take abuse, the ride is actually better with a full tank of water though, thanks to the weight. The handling really isn't that bad, but I would NOT drive one over 65-70, they just were not made to go that fast.

 

[Jahee]

Originally posted by: eos

Originally posted by: Jahee

Originally posted by: skyking
When the lane gets worn, it can be bad. You'll sometimes see a truck in the second lane because it is so bad in lane 1.

So its common? and on a perfectly balanced and rounded wheel it shouldn't happen...?

What does it feel like to the driver? just alot of shock to the steering wheel as in say... driving over cobbles? or a rumble strip?

This country is littered with interstates in horrible condition. I think the only interstate I have not driven on is I-8 and maybe a couple other. And they all have bad sections. Some run for miles in bad shape.

So on rough surface, no matter the condition of the truck it'll happen, basically wherever there's potholes you'll get that 'bouncing effect' is what you mean? sorry i don't quite understand that.

 

[Jahee]

Double post...