Effect of weight on braking for trucks.

[jimh406]

Instead of further morphing the other thread, I thought it would be interesting to discuss the effect of weight and speed for trucks since we obviously increase our weight when we add TCs.

Obviously, it is talking about drum brakes, but I think the principles apply. It seems like improving the linings and doing things to decrease heat would be helpful.

My source is https://www.truckinginfo.com/347664/how-speed-weight-and-grades-affect-brakes.

Several things happen to hot drum brakes that will reduce their stopping ability--a condition often referred to as brake fade. Most lining materials lose some frictional capability at high temperatures. Poor quality linings may lose up to a third of their effectiveness at temperatures above 600°F.

The laws of physics work against truck brakes in other ways too. It's accepted that if truck weight is doubled, stopping power must be doubled. But if speed is doubled, stopping power must be increased four times. If both weight and speed are doubled, stopping power must be increased eight times.

In practical terms, that means a fully loaded truck descending a hill at 60 mph will require eight times the stopping power of a lightly loaded truck traveling at 30 mph. Or, the brakes on the faster heavier truck will be doing eight times as much work as the brakes on the slower lighter truck. In other words, the brakes must absorb or dissipate eight times as much heat.

Even small increases in speed can make a big difference to the demands on the brakes. An increase in speed from 50 mph to 60 mph --an increase of 25%--would increase the stopping distance on level ground by 56%. You can guess what happen on steep hills at high speed.

[time2roll]

Just drive safe already. Please try to accommodate those that prefer to drive slower. Don't get all stupid because you have to pause a bit to pass someone. There is plenty of road and time for everyone to get along. Keep right unless passing. The larger the vehicle and the closer you are to max weight just leave a bit more extra space. Far better to have a 5 minute delay to pass than a 5 hour delay getting mixed up in a wreck.

[Grit_dog]

Well this got as far into the weeds as most threads, although tons expected since this was bait to start an argument following the previous thread about weight.....go figure.

[Bert_the_Welder]

pianotuna wrote:

Bert the Welder wrote:


https://sites.psu.edu/siowfa15/2015/09/18/is-driving-faster-safer/ .

Mark Twain,

There are liars, **** liars, and statistics.

One can cherry pick a data set to prove just about anything you want.

Zero need to cherry pick data. Zero need for data, even. I go by what I see and experience daily.
One can also cherry pick quaint quips for comedic affect.

[Bert_the_Welder]

noteven wrote:

Bert the Welder wrote:

jimh425 wrote:

JRscooby wrote:
Let's see, 85-62 is 23. Is it your opinion that most drivers can not miss a stopped car on a 4 lane road when driving 23 MPH? And the fault is the slow drivers?

It’s not about fault. It’s about increasing the chance of being in an accident.

https://sites.psu.edu/siowfa15/2015/09/18/is-driving-faster-safer/

According to state and federal studies, drivers that are driving significantly below the average speed are the ones that are most likely to get involved in an accident. Studies show that the most accidents occur when the driver is driving at 10 mph slower than the speed limit. So someone going 45 in a 55 has a bigger chance of getting into an accident than someone driving at 65-70 mph.

The main problem on roads that causes accidents is the differences in speed, rather than speed itself. While some people are going faster than other, some go slower which causes the traffic to flow unevenly. If the speeds limits are raised to comply with the actual travel speeds, the roads become safer, because the traffic now flows more evenly and people start going to the same speeds. This actually shows that drivers are not affected by the speed limits that much, but rather slow drivers. The National Highway Traffic Safety Administration (NHTSA) Says that only 30% of the accidents that are fatal are accidents in which the driver was speeding. This does not mean that the speeding actually is the cause of the accident. A study conducted by the Florida Department of Transportation says that accidents that were caused by speeding is actually 2.2%. This shows that if people drive faster all together it is actually safer than driving slow.

This is of zero surprise to me. Additionally, people driving too slow cause frustration for others resulting in loss of attention and more aggressive driving, particularly on single lane roads. Also, when driving faster, IMO, you pay even more attention and are more focused on what's going on around you. Poor road way design contribute to this with merging in on the left, turn lanes on the left side of highways and zero enforcement of not using the left lane for traveling.
And if yo do want to go slow, then there's nothing wrong with that. Adjust your route or at least have the courtesy to pull over. Absolutely loved seeing the signs in WA that stated you must pull off if you have more then 5 vehicles behind you. And they even provide short, right side slow down lanes so you can, safely. Bloodee brilliant.

Now Bert if we could just edumacate western Canadian drivers that where "passing lanes" are built on 2 lane routes, you don't floor it to 140 klicks so the line of 30 eleventeen vehicles that has been following you for an hour now cannot safely pass...

You must have been following me just the other day. Driving back home on a long winding single lane stretches with limited passing. The slow pokes hugging the center line, not giving others a clear look ahead on the broken line sections. And not moving over or slowing when being passed. Then got to the all too short double lane passing sections and sure enough those driving 5-10 under the whole time sped up so the rest of us can't pass efficiently. Would have been more frustrating had I not been in the Mrs. Audi. It took 5-6000 rpm and 160 km/hr to get around them. One dumb@$$ in a plumbing truck had 16 cars behind him and launched up to at least 120 at the passing lane after driving 85-90 the rest of the time in the 100 zones. That's 100% being an @$$ whole and dangerous.

[deserteagle56]

noteven wrote:
What I notice about 80mph speed limits is pretty much no one is speeding.

Where's the revenue opportunity in that?

I don't know where you are driving to see no one is speeding. 80 mph is the speed limit here in Nevada on the freeways - and every week our local paper has a list of the Californians the Nevada Highway Patrol nabbed for doing 100+. One was over 120!

But you are correct - it seems that I, and most other drivers I see, find 80-85 as fast as we need to go. There's always a few that just have to push it........

[Kayteg1]

noteven wrote:
What I notice about 80mph speed limits is pretty much no one is speeding.

Where's the revenue opportunity in that?

You might be surprised.
For last 20 years, every couple of years I drive I-80 east to west.
The freeway in NB and WY has 75 mph limit and never in the past I would see speed trap, or radar reinforcement on the road.
Last time I drove it like 3 years ago and NB had 3 radars on the stretch.
But than last cannonball drive averaged 103 mph /193mph top and no tickets. Where is LEO when you need 1 ?

[noteven]

Bert the Welder wrote:

jimh425 wrote:

JRscooby wrote:
Let's see, 85-62 is 23. Is it your opinion that most drivers can not miss a stopped car on a 4 lane road when driving 23 MPH? And the fault is the slow drivers?

It’s not about fault. It’s about increasing the chance of being in an accident.

https://sites.psu.edu/siowfa15/2015/09/18/is-driving-faster-safer/

According to state and federal studies, drivers that are driving significantly below the average speed are the ones that are most likely to get involved in an accident. Studies show that the most accidents occur when the driver is driving at 10 mph slower than the speed limit. So someone going 45 in a 55 has a bigger chance of getting into an accident than someone driving at 65-70 mph.

The main problem on roads that causes accidents is the differences in speed, rather than speed itself. While some people are going faster than other, some go slower which causes the traffic to flow unevenly. If the speeds limits are raised to comply with the actual travel speeds, the roads become safer, because the traffic now flows more evenly and people start going to the same speeds. This actually shows that drivers are not affected by the speed limits that much, but rather slow drivers. The National Highway Traffic Safety Administration (NHTSA) Says that only 30% of the accidents that are fatal are accidents in which the driver was speeding. This does not mean that the speeding actually is the cause of the accident. A study conducted by the Florida Department of Transportation says that accidents that were caused by speeding is actually 2.2%. This shows that if people drive faster all together it is actually safer than driving slow.

This is of zero surprise to me. Additionally, people driving too slow cause frustration for others resulting in loss of attention and more aggressive driving, particularly on single lane roads. Also, when driving faster, IMO, you pay even more attention and are more focused on what's going on around you. Poor road way design contribute to this with merging in on the left, turn lanes on the left side of highways and zero enforcement of not using the left lane for traveling.
And if yo do want to go slow, then there's nothing wrong with that. Adjust your route or at least have the courtesy to pull over. Absolutely loved seeing the signs in WA that stated you must pull off if you have more then 5 vehicles behind you. And they even provide short, right side slow down lanes so you can, safely. Bloodee brilliant.

Now Bert if we could just edumacate western Canadian drivers that where "passing lanes" are built on 2 lane routes, you don't floor it to 140 klicks so the line of 30 eleventeen vehicles that has been following you for an hour now cannot safely pass...

[noteven]

What I notice about 80mph speed limits is pretty much no one is speeding.

Where's the revenue opportunity in that?

[jimh406]

pianotuna wrote:
One can cherry pick a data set to prove just about anything you want.

Can’t wait to read the links that has your proof.

[pianotuna]

Bert the Welder wrote:


https://sites.psu.edu/siowfa15/2015/09/18/is-driving-faster-safer/ .

Mark Twain,

There are liars, **** liars, and statistics.

One can cherry pick a data set to prove just about anything you want.

[KD4UPL]

StirCrazy wrote:

KD4UPL wrote:

You have to be careful telling people they should get a diesel because it will help them slow down better. This is not at all true. A diesel engine has less engine braking then a gas engine.

All new turbo diesels have them in one form or another and have had them for quite a few years. weather it is by use of a varable vane turbo or a true exhaust brake, no gas engine has close to the engine braking power of the moderen disels.

Steve

New maybe but the line was "braking is one reason to consider a diesel engine." This does not universally apply. Many, many older diesels do not have an exhaust brake; I drive one every day, a 2005 Duramax dually.
I don't think even all newer diesels have them. The 2015 Ford Transit van diesel I used to drive at work did not have one. As far as I know Duramax vans, Sprinter vans, Nissan pick-ups, RAM Eco-diesel, F-150 diesels do not have them either.

[Grit_dog]

Kayteg1 wrote:
When I drive with speed limit, I got sleepy. Is that safe?

Nothing keeps you awake like doing 100mph with the window down!

I'd like to have a drink or 8 with you some day Kayteg!

[noteven]

So heavy trucks should be designed and powered to maintain 75mph up any interstate grade when loaded at GCW for safety?

[jimh406]

JimK-NY wrote:
The Montana speed limit on open Interstates might be up to 80 mph, daylight driving only, but that is for cars, Suvs, light trucks. Heavy trucks are restricted to a max of 65 mph.

No way am I going to drive my truck camper at 80 or even past 70. When I upgraded to Rickson 19.5 wheels and Firestones, the max speed rating for the Firestones was 70.

Nobody said you need to drive 80 with a TC. Anything you can do to reduce the difference would be helpful. And ... if you want to drive really slow, it would be safer to avoid the interstate when possible.

Fwiw, there isn’t a statewide night time limit that is different than the daytime on interstates. The heavy truck limit is 70 for day/night as well.

https://www.mdt.mt.gov/visionzero/roads/speedlimits.shtml