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Sorta. Tractor and trailer and load can not weight over 80000lbs.
sure they can. we adopted uniform length and weight decades ago. (max TT length, tractor PLUS trailer was 55ft in some states! making coast to coast runs challenging.) if you want to go over 40T, just permit for it or reg/haul in a state that allows for it since 1992. AND, there still are some states that allow triples. just have to follow the 'bridge formula'
Maybe the OP expects jet-engine powered semis? Cummins 777 here we come.
It's unfortunate that gas mileage and maintenance costs are such a hassle. Imagine the contrary. Take for example the Brayton cycle gas-turbine from a Chinook helicopter, the Lycoming T55-GA-714A. It makes around 4,700 shaft hp. They only weigh around 800 pounds... probably less than the diesel in a regular 18-wheeler truck. Put a planetary gear reduction on it (huge reduction in rpm and concomitant multiplication of torque), with a secondary gear box for gear-changes and reverse. Neat, eh?
Too much soy in his diet, or he would not have made that post.
Big trucks are actually engineering marvels. They move huge amounts of freight for similar fuel economy as a 2000 chevy 2500 pickup pulling a boat. Imagine that relatively small amount of fuel propelling 53 feet of heavy stuff across 2 or 3 states.
You got that right. In the late 1970s I worked at the Peterbilt Truck factory in Newark, CA before it closed and moved to Denton, TX. Every work day, 26 custom built trucks drove off the assembly line. Unlike a typical automotive factory that builds thousands of almost identical cars, one after the other, the Peterbilt factory had a separate custom build sheet for each truck.
Sure, there were some fleet orders when a customer ordered a dozen or more of a certain truck, but there were also cases where you could have 26 completely different trucks in a row on the line. Imagine the details, engineering, and parts logistics. Each truck with a different combination of engine, transmission, axles and hundreds of other components, not to mention different body style (cabover, conventional, sleeper cabs or not, etc). Many of the trucks were almost works of art! It was impressive, a job experience I have never forgotten.
I notice this every day when Im driving the expressway, any type of uphill grade and tractor trailers cannot maintain their speed, some of the more hilly areas, they can barely maintain 30mph!
These are not just older TTs either, even the brand new ones seem to be drastically effected by up hill grade.
If it was due to them being loaded overweight, towing more than allowed by law, I would think trucks going very slow up grades would be an easy target for police to pull them over for weight offenses, but Ive not seen many pulled over by police.
One difference I have noticed over the years, the trailers are getting longer, 48' used to be the most widely used, now its 53', but the weight limits are still the same I assume, but many get around this by using 2-3 smaller trailers, I see more and more TT towing 3 trailers today too. (many more than past years).
It's not because they are over loaded. It has to do with transmission gearing, momentum and gravity.
In hilly areas they need to be careful going down hills because of the weight they carry can make them difficult to control. Going up requires lower gears lower gears produce more torque but cost horsepower and higher gears just don't have the torque to get the vehicle up the hill.
This is the lamest thread I've ever seen in the Automotive forum. I'd almost think this is trolling.
Do you realize how much power it would take to pull 80,000 lbs up a 6% grade at 55 mph? You'd probably need to make the engine compartment 50% bigger. A bigger engine would mean the tractor trailer would tow less due to weight limits on the highway. And it would be a waste of diesel just for those few times it goes uphill.
sure they can. we adopted uniform length and weight decades ago. (max TT length, tractor PLUS trailer was 55ft in some states! making coast to coast runs challenging.) if you want to go over 40T, just permit for it or reg/haul in a state that allows for it since 1992. AND, there still are some states that allow triples. just have to follow the 'bridge formula'
I guess you didnt read the post I was replying to. Not many trucks are going to be HAULING 80 grand, every day. Sure I know about overweight permits, but to keep the replies to the OP simple, I excluded that. This is an old post to styart with and R hasnt posted in a while.
Our region is 105,500#, but I need to go to the state next door to run triples (5 minutes across a bridge).
Power can be handy, but gears are important, and road conditions. As a lifelong CDL driver in Mtns, You don't want to come down any faster than you went up, (and you better go down VERY slow in many instances.)
According to the Federal Highway Administration, most US states limit the lengths of LCVs to 110 feet for double-trailer combinations and 115.5 feet for triple-trailer combinations. Moreover, the maximum weight allowed depends on the number of axles on the trailers.
For instance, a 7-axle rocky mountain double-trailer allows up to 120,000 pounds gross weight. At the same time, an 8-axle B-train double-trailer hauls 124,000 pounds and a 9-axle turnpike double-trailer hauls up to 148,000 pounds. Meanwhile, a triple-trailer combination typically hauls up to 132,000 pounds gross weight
Only IL and PA are making the cross country use of LCV's difficult.
WY and CA have their own issues, and diesel semis will eventually (soon) be a thing of the past in CA.
Last edited by StealthRabbit; 07-14-2023 at 11:58 AM..
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