The maximum weight for a tractor-trailer rig in the United States is 80,000 pounds, 40 short tons or 36.36 metric tons.
A tractor-trailer rig is surprisingly streamlined. The cab is shaped and sized for the front of the trailer to ride closely in its wake, often with fairings that reach as close to the trailer as practicable. Sure it’s a brick, but it’s ONE brick:
A pickup truck towing a trailer isn’t anywhere near that slick, even with a gooseneck trailer, the trailer is often taller and wider than the cab. It’s a brick, attached to another, larger brick being pulled through the turbulent disturbed air from the first brick:
In terms of torque, EVs have a significant advantage. Electric motors produce a lot more torque at low to zero RPM than internal combustion engines do. Limited slip differentials or all-wheel drive are solved problems.
The additional energy required to accelerate the additional weight up to speed isn’t that much of a problem as an EV will get that back with regenerative braking. Well, some of it. Most trailers have brakes of their own that do help with braking distance but are there mostly to keep the hitch under tension to prevent jackknifing. An ICEV figures on losing all of that energy to friction braking, a BEV plans on recovering some of it. An electric pickup carrying 1000 pounds in the bed will be more efficient than one pulling a 1000 pound trailer, in most cases.
The maximum weight for a tractor-trailer rig in the United States is 80,000 pounds, 40 short tons or 36.36 metric tons.
I’m not sure what you’re getting at with this. Here in Australia road trains haul 90 metric tons of grain and fertilizer all the time, that doesn’t include the weight of the trailers.
Regardless, I’m not quite sure what you’re trying to illustrate - your example of a “streamlined vehicle” undoubtedly consumes a lot more diesel than your example of a vehicle which is not streamlined. Isn’t that antithetical?
In terms of torque, EVs have a significant advantage.
Yes, but a “truck” with a 4 ton towing capacity obviously needs motors with more torque than those on a tesla.
The additional energy required to accelerate the additional weight up to speed isn’t that much of a problem as an EV will get that back with regenerative braking. Well, some of it.
As little as 5 to 10% on the highway, not particularly significant. Installing regenerative brakes on a trailer is a lot of additional cost and complexity.
In the United States, if you need more than about 20 tons of freight moved, you use the railroad not the highway. “Road trains” aren’t a thing here.
Regardless, I’m not quite sure what you’re trying to illustrate - your example of a “streamlined vehicle” undoubtedly consumes a lot more diesel than your example of a vehicle which is not streamlined. Isn’t that antithetical?
In absolute terms, yes. A semi truck consumes more fuel than a pickup truck. So does a diesel locomotive. The point is the difference in aerodynamic drag with and without the trailer.
Aerodynamically, a semi truck is the same shape with and without a trailer. Somewhat streamlined nose, flat sides, flat rear. With the trailer attached, that flat rear is just 50 feet further away. A semi truck without a trailer will make better fuel economy because it doesn’t have to accelerate the additional weight or overcome the friction in the additional axles, but the cab has already taken most of the aerodynamic punishment it can.
With a non-streamlined pickup truck, the additional wheel friction and acceleration energy are factors, but you’re also functionally doing this:
So a pickup truck sees a much bigger punishment to fuel economy when you hitch up a trailer than a semi does.
Yes, but a “truck” with a 4 ton towing capacity obviously needs motors with more torque than those on a tesla.
Not necessarily. My S10’s 4.3L V6 engine makes 200 horsepower and 200 foot pounds of torque. It’s rated to tow 7600 pounds, with the addition of a transmission cooler. A Tesla Model Y is rated at 397 horsepower and 389 foot pounds of torque, it is rated to tow 3500 pounds. A lot more factors than horsepower and torque go into a tow rating. The strength of the frame at the hitch, a height sensing proportioning valve, the duty cycle ratings of the power train to name a few. It’s not about “Can this car get this weight moving” it’s “can this car perform a safe emergency stop 9 hours into a 10 hour journey towing this weight?”
As little as 5 to 10% on the highway, not particularly significant.
See that’s the funny thing about EVs. ICEVs get better fuel economy on the highway because the constant aerodynamic drag at cruising speed is less than all the braking you do in the city. EVs are the other way up, because of regenerative braking they get a lot of their energy back when braking, but you can’t get aerodynamic drag back. And that’s without the additional drag of a trailer.
The maximum weight for a tractor-trailer rig in the United States is 80,000 pounds, 40 short tons or 36.36 metric tons.
A tractor-trailer rig is surprisingly streamlined. The cab is shaped and sized for the front of the trailer to ride closely in its wake, often with fairings that reach as close to the trailer as practicable. Sure it’s a brick, but it’s ONE brick:
A pickup truck towing a trailer isn’t anywhere near that slick, even with a gooseneck trailer, the trailer is often taller and wider than the cab. It’s a brick, attached to another, larger brick being pulled through the turbulent disturbed air from the first brick:
In terms of torque, EVs have a significant advantage. Electric motors produce a lot more torque at low to zero RPM than internal combustion engines do. Limited slip differentials or all-wheel drive are solved problems.
The additional energy required to accelerate the additional weight up to speed isn’t that much of a problem as an EV will get that back with regenerative braking. Well, some of it. Most trailers have brakes of their own that do help with braking distance but are there mostly to keep the hitch under tension to prevent jackknifing. An ICEV figures on losing all of that energy to friction braking, a BEV plans on recovering some of it. An electric pickup carrying 1000 pounds in the bed will be more efficient than one pulling a 1000 pound trailer, in most cases.
I’m not sure what you’re getting at with this. Here in Australia road trains haul 90 metric tons of grain and fertilizer all the time, that doesn’t include the weight of the trailers.
Regardless, I’m not quite sure what you’re trying to illustrate - your example of a “streamlined vehicle” undoubtedly consumes a lot more diesel than your example of a vehicle which is not streamlined. Isn’t that antithetical?
Yes, but a “truck” with a 4 ton towing capacity obviously needs motors with more torque than those on a tesla.
As little as 5 to 10% on the highway, not particularly significant. Installing regenerative brakes on a trailer is a lot of additional cost and complexity.
In the United States, if you need more than about 20 tons of freight moved, you use the railroad not the highway. “Road trains” aren’t a thing here.
In absolute terms, yes. A semi truck consumes more fuel than a pickup truck. So does a diesel locomotive. The point is the difference in aerodynamic drag with and without the trailer.
Aerodynamically, a semi truck is the same shape with and without a trailer. Somewhat streamlined nose, flat sides, flat rear. With the trailer attached, that flat rear is just 50 feet further away. A semi truck without a trailer will make better fuel economy because it doesn’t have to accelerate the additional weight or overcome the friction in the additional axles, but the cab has already taken most of the aerodynamic punishment it can.
With a non-streamlined pickup truck, the additional wheel friction and acceleration energy are factors, but you’re also functionally doing this:
So a pickup truck sees a much bigger punishment to fuel economy when you hitch up a trailer than a semi does.
Not necessarily. My S10’s 4.3L V6 engine makes 200 horsepower and 200 foot pounds of torque. It’s rated to tow 7600 pounds, with the addition of a transmission cooler. A Tesla Model Y is rated at 397 horsepower and 389 foot pounds of torque, it is rated to tow 3500 pounds. A lot more factors than horsepower and torque go into a tow rating. The strength of the frame at the hitch, a height sensing proportioning valve, the duty cycle ratings of the power train to name a few. It’s not about “Can this car get this weight moving” it’s “can this car perform a safe emergency stop 9 hours into a 10 hour journey towing this weight?”
See that’s the funny thing about EVs. ICEVs get better fuel economy on the highway because the constant aerodynamic drag at cruising speed is less than all the braking you do in the city. EVs are the other way up, because of regenerative braking they get a lot of their energy back when braking, but you can’t get aerodynamic drag back. And that’s without the additional drag of a trailer.