Can We Build A Hybrid Semi?

[Aaron]

Recently I suggested in a N&P thread that commercial tractor-trailers be given a hybrid diesel-electric engine. Someone objected saying that the weight a semi pulls is too much for a hybrid.

So I thought I'd open it up to the board. Do you think it would be viable?

My opinion:Yes. There are already hybrid APC's under testing by the military. And althought the heaviest weight I am aware of them hauling is the 11 tons of APC, I don't see why the engines couldn't be scaled up to be used by a semi. The only frawback I can think of is that the battery pack may be to heavy to be practical.

[Sea Skimmer]

There certainly is no technical reason why it couldn't be done. However heavy long haul trucks are already quite fuel efficient at what they do, and hybrids shine at stop and go traffic when they can economize on fuel via regenerative braking. So the actual fuel savings your likely to get would be much less then the results you see on cars.

[Meest]

I thought hybrid/electric motors had good torque? That would be perfect for trucks which are most geared to low-end power. How much top end they need I don't know, their engines do have reasonable horsepower as well, something most hybrids lack.

[Aaron]

I thought hybrid/electric motors had good torque? That would be perfect for trucks which are most geared to low-end power. How much top end they need I don't know, their engines do have reasonable horsepower as well, something most hybrids lack.

It's my understanding that Hybrids, at least the Ford Escape have similar power to their gasoline equivilants. And the APC engines being tested actually outperform their diesel counterparts.

[Sea Skimmer]

It's my understanding that Hybrids, at least the Ford Escape have similar power to their gasoline equivilants.

Most hybrids cars have less power, even electric and gas combine (something which can be sustained only as long as the batteries hold), compared to comparable conventional vehicles. But part of that is simply because the designers are simply trying to make the things as efficient as possible, damn the lack of performance and low acceleration.

And the APC engines being tested actually outperform their diesel counterparts.

On the other hand, I suspect the APC's basic diesel engine cost far less and was designed two decades or more earlier. Not that hybrid armor is a bad idea.

[Aaron]

Most hybrids cars have less power, even electric and gas combine (something which can be sustained only as long as the batteries hold), compared to comparable conventional vehicles. But part of that is simply because the designers are simply trying to make the things as efficient as possible, damn the lack of performance and low acceleration.

Well in all honesty does the average driver need a vehicle that has hundreds of horsepower? My Grandmother drives a 84 Honda Civic with around 90, and it works just fine.

Now a Semi will need to have alot of torque but acceleration doesn't seem to be too important, they don't accelerate very fast fully loaded anyways, with diesels.

On the other hand, I suspect the APC's basic diesel engine cost far less and was designed two decades or more earlier. Not that hybrid armor is a bad idea.

The original engine is certainly cheaper and would probably be easier to maintain. I believe the ones they were testing against were M113A3's, but I'm unsure as to the age of that engines design.

I think hybrid armor is a great idea. Modern AFV's use a hell of a lot of fuel, so any savings would be a boon to the logistics side of the house. Plus hybrids are quieter. Although I hear that the M1's turbine is very quiet compared to a similar diesel, although it's lousy on fuel.

[Petrosjko]

I'm not an engine guy, at least not to the extent of really paying attention to the latest developments and new toys. I've gotten by knowing enough to do basic maintenance on the CATs, Detroits and Cummins engines that served me in my time on the road.

But I can give an idea of some of the performance requirements for the standard OTR tractor for those more knowledgable about the hybrids to play with.

-For a 48 and Canada cruiser, minimum of 350 horsepower, and that's considered barely acceptable for powering full-gross loads over the Rockies. They did run on weaker engines in the past, but for everyone's sake it's best to keep horsepower in the optimal range. Better for timetables, better for drivers, safer because slow-moving vehicles do constitute a road hazard.

-The current legal full-gross weight that can be pulled in all states without any special permits is 40 tons. Gotta be able to hump that over hill and dale.

-The ability to run roughly five to seven hundred miles between refuelings, on 180 gallons of diesel, of which up to 170 is usable, with a full-gross load.

-Maintenance cycle, roughly a service every month and a half to two months, for the average solo driver. Ticky-tack maintenance every month to two months. Serious tune-up work once to twice a year.

-Basic maintenance, all fluid replenishments, quickly and easily doable in the field.

-Lifespan. The current typical engine lifespan, for a Detroit Series Sixty that's properly cared for and babied, exceeds six million miles.

-Acceleration is important. Yes, it takes a fully-loaded truck over a mile to get up to speed, but every ounce of that acceleration counts when trying to merge into crowded traffic from an entry ramp, and that is a safety issue.

-Tolerance for environmental temperature conditions to exceed 120 degrees farenheit and to go below... well, for Canadian-authorized units, however the fuck cold it gets up there.

[Petrosjko]

Incidentally, there are proposals cropping up to increase the weight limit and length limit for OTR units, some bumping the 100k mark. It's an interest of the industry in order to make incremental cuts in the manpower requirements.

The proposals were getting some consideration, from what I've heard, but I doubt they'll go through due to the increased strain that would put on our already stressed road repair services.

[Quadlok]

Now, I make no claim to expertise, but wouldn't the airbrakes on a semi not play well with the whole concept of regenerative braking, as they are rather more abrupt than your standard disc or drum?

[Petrosjko]

I don't know the technical details, but if it's a requirement for power savings, it'd be wasted in most OTR tractors. There are a lot of stretches in this country where you can go without tapping the brakes more than three or four times an hour, and oftentimes that's simply to disengage the cruise and let your speed back off naturally. Drivers of old were trained to minimize braking as much as possible, though a lot of the refined techniques such as left-foot clutching have been lost in the modern era. Nevertheless, braking is still somewhat minimized by natural deceleration and downshifting whenever possible, and utilizing the engine brake in the appropriate places.

(Where the appropriate places are is a matter of much debate both in the industry and in many city councils.)

[Star-Blighter]

Well in all honesty does the average driver need a vehicle that has hundreds of horsepower? My Grandmother drives a 84 Honda Civic with around 90, and it works just fine.

Now a Semi will need to have alot of torque but acceleration doesn't seem to be too important, they don't accelerate very fast fully loaded anyways, with diesels.

On the other hand, I suspect the APC's basic diesel engine cost far less and was designed two decades or more earlier. Not that hybrid armor is a bad idea.

You haven't seen an independent diesal rig pushing 95 mph while "dead-heading" on I-5, have you.

Semi-trucks only go slow when they absolutely HAVE TO (this varies depending on the temperment of the driver).

[The Third Man]

There's also the weight problem. Since HGVs are limited by gross vehicle weight, any additional electric gubbins would eat into the weight of cargo that the vehicle could transport. This would drop the earning potential of the vehicle and be an inefficiency in its own right.

Hybrid cars this isn't really a problem for, as they aren't optimised to shift the maximum amount of cargo weight for a given gross weight.

I think natural gas is the way to go for HGVs, but it hasn't proved popular with some drivers.

[Petrosjko]

There's also the weight problem. Since HGVs are limited by gross vehicle weight, any additional electric gubbins would eat into the weight of cargo that the vehicle could transport. This would drop the earning potential of the vehicle and be an inefficiency in its own right.

Hybrid cars this isn't really a problem for, as they aren't optimised to shift the maximum amount of cargo weight for a given gross weight.

I think natural gas is the way to go for HGVs, but it hasn't proved popular with some drivers.

Good point on the gross weight, and there's also a factor in legal weight distribution.

The 48 state standard is maximum of 6 tons on the steers (front two tires) and 17 tons each on the drives (eight tractor tires that provide locomotion) and trailer tires (self-explanatory).

As an aside, you want every ounce of that six tons on those steers that you can get, especially in inclement weather, and past that you want as much load as you can get on the drives as well, all for traction purposes. If any portion of the unit's gonna take off and skate, let it be the back end that doesn't do any locomotion or directing.

Anything that shifts more weight to the front of the unit can fuck the weight distribution and reduce the cargo capacity of a unit, even if it doesn't necessarily move it out of its legal GVW parameters. (GVW=Gross vehicle weight)

That's been a problem with at least three new-model trucks that came out in the past decade... they were both overheavy as tractors to begin with, cutting their capacity, and they fucked up the weight distribution between the steers and drives, making it hard to achieve ideal balance.

[Sea Skimmer]

I think natural gas is the way to go for HGVs, but it hasn't proved popular with some drivers.

When big trucks crash at highway speeds not much will save the fuel tank from going crunch, and that's when the low flash point of diesel is very nice at life saving. A natural gas fuel tank for a big rig would be huge and would weigh an enormous amount if it was sufficiently reinforced to survive crashes. Theres also just the issue of refueling, hybrids can just fill up at a normal gas station. Natural gas is less easily obtained.

[The Third Man]

When big trucks crash at highway speeds not much will save the fuel tank from going crunch, and that's when the low flash point of diesel is very nice at life saving

True, but that's not what actually upset the drivers I encountered - they were more upset with the different drving characteristics, and particullarly irked by the fact that their cabs were hotter (due to them sitting on top of a catalytic converter, one of the nice features you can add when using natural gas)

A natural gas fuel tank for a big rig would be huge and would weigh an enormous amount if it was sufficiently reinforced to survive crashes.

Well yes, if it had to survive all crashes. The ones currently in use are made from all sorts of funky carbon-fibres and the rest; they supposedly have an acceptable level of crash survivability.

Theres also just the issue of refueling, hybrids can just fill up at a normal gas station. Natural gas is less easily obtained

Very true. The range of the vehicle is limited compared to diesel too (those tank issues again) which compounds the problem. A few years ago I was working with a conversion proct, and in the UK the natural gas vehicles were fine in England and Wales, but (initially at least) just couldn't go to northern Scotland at all, where gas filling stations were just too few and far between for the vehicles to even reach on a tankful.

In the UK natural gas has one killer advantage - it's quiet. Very quiet - so much so that it's weird when you first encounter a 40-ton vehicle that makes just transmission and suspension noises. What this means is that they are permitted to operate at night in residential or town-centre areas (the UK has a noise curfew in many places) and this in turn means they are ideal for supermarkets who like to do their re-stocking deliveries during the night.

[Sea Skimmer]

Well yes, if it had to survive all crashes. The ones currently in use are made from all sorts of funky carbon-fibres and the rest; they supposedly have an acceptable level of crash survivability.

I'd prefer a fuel tank not made of a flammable material.

[Petrosjko]

True, but that's not what actually upset the drivers I encountered - they were more upset with the different drving characteristics, and particullarly irked by the fact that their cabs were hotter (due to them sitting on top of a catalytic converter, one of the nice features you can add when using natural gas)

Any specifics on the differing driving characteristics? One that's just a matter of re-aclimation would be the lack of engine noise, because nobody more than a month or two out of training actually shifts by the tach, they go by engine noise. That's not a big issue, that'd just be a pet peeve.

Excess cab heat definitely would be an issue, though. Those cabs can heat up pretty good already, especially chugging the hills in desert areas during the summer, and the A/C flat cannot keep up.

Furthermore, cab cooling while sleeping is a vital issue, one the companies usually try to duck when working to minimize idling. But few people can comfortably sleep in hundred to hundred and fifteen degrees farenheit, or more.

[The Third Man]

Any specifics on the differing driving characteristics?

As I recall, and I got it second-hand from one of the managers, the gas-conversions had a narrow and somewhat lower power-band, and I imagine that as you point out, dealing with this is exacerbated by the lack of engine noise. It wasn't an issue of being under-powered though; I remember the gearboxes had to be uprated because after the conversion the engines produced more power.

There was also a more complicated start-up/shut-off procedure, I forget the details, but it was probably to do with all the gas valves, and/or the less-than-fully-automated ignition module (have to put spark-plugs in to burn natural gas ) that the early conversions used.

Engine-braking effects would be dramatically reduced, because the donor diesel engines had their compression ratios dropped, but I don't remember this being one of the complaints.

[Petrosjko]

As I recall, and I got it second-hand from one of the managers, the gas-conversions had a narrow and somewhat lower power-band, and I imagine that as you point out, dealing with this is exacerbated by the lack of engine noise. It wasn't an issue of being under-powered though; I remember the gearboxes had to be uprated because after the conversion the engines produced more power.

Reverting to tach-sighting and having more gears to work through would irritate the fuck out of me, but as I said, it's just an annoyance and not truly a reason to avoid adoption of the system.

There was also a more complicated start-up/shut-off procedure, I forget the details, but it was probably to do with all the gas valves, and/or the less-than-fully-automated ignition module (have to put spark-plugs in to burn natural gas ) that the early conversions used.

Again, annoyance but not a big deal. However, adding additional system elements and hence maintenance requirements is bad.

Engine-braking effects would be dramatically reduced, because the donor diesel engines had their compression ratios dropped, but I don't remember this being one of the complaints.

Bad bad bad. A good driver shouldn't rely on his Jakes to keep him out of trouble, but they are a life-saving tool and need to be as powerful as they can be.

[sketerpot]

Now a Semi will need to have alot of torque but acceleration doesn't seem to be too important, they don't accelerate very fast fully loaded anyways, with diesels.

You haven't seen an independent diesal rig pushing 95 mph while "dead-heading" on I-5, have you.

Semi-trucks only go slow when they absolutely HAVE TO (this varies depending on the temperment of the driver).

There's a difference between speed and acceleration. A semi truck might go really fast---but it'll take some time for it to reach that speed.

[Broomstick]

Incidentally, there are proposals cropping up to increase the weight limit and length limit for OTR units, some bumping the 100k mark. It's an interest of the industry in order to make incremental cuts in the manpower requirements.

The proposals were getting some consideration, from what I've heard, but I doubt they'll go through due to the increased strain that would put on our already stressed road repair services.

Here in NW Indiana we have steel mills that ship huge rolls of steel to various manufacturers, mostly auto plants in Michigan. These trucks are authorized to haul much, much higher weights than normally allowed on the roads (I don't recall the exact number, but it's big). These "Michigan Trains", as they're called, are restricted to specific routes. They chew the living hell out of those roads.

Then there are some basic physics problems with such a heavy load. For instance, if they front of the truck stops and, for whatever reason, the load doesn't (perhaps it was not adequately secured, perhaps the tractor encountered a solid object too suddenly, whatever) it pretty much squashes the driver and any vehicles for a good couple hundred feet in front of the rig. Needless to say, if one runs over you, you're dead. Accidents with these trucks have knocked down buildings and bridges. If the load falls off the trailer it tends to leave a 6-8 inch gouge in the pavement. The last time there was an altercation between one of these trucks and a commuter train the truck won.

Most of us around here give these guys lots of room on the road.

I understand the economic incentive to reduce manpower, but at a certain point you can reach dimishing returns. Even if you reduce the frequency of accidents, accidents will still happen because
1) People make mistakes
2) Machines break
3) We can't control the weather
The higher the weight the larger the potential consequences of an accident. I also suspect that the greater the weight the more skillful the driver is required to be in order to handle it safely.

[Petrosjko]

Here in NW Indiana we have steel mills that ship huge rolls of steel to various manufacturers, mostly auto plants in Michigan. These trucks are authorized to haul much, much higher weights than normally allowed on the roads (I don't recall the exact number, but it's big). These "Michigan Trains", as they're called, are restricted to specific routes. They chew the living hell out of those roads.

Haven't hauled that particular variety of overload, but I have made steel runs. NO FUN.

There are some permissible overweights that are just mindboggling. For example, nuke waste units can run 125K, just for truck and trailer before any cargo is loaded on.

Then there are some basic physics problems with such a heavy load. For instance, if they front of the truck stops and, for whatever reason, the load doesn't (perhaps it was not adequately secured, perhaps the tractor encountered a solid object too suddenly, whatever) it pretty much squashes the driver and any vehicles for a good couple hundred feet in front of the rig. Needless to say, if one runs over you, you're dead. Accidents with these trucks have knocked down buildings and bridges. If the load falls off the trailer it tends to leave a 6-8 inch gouge in the pavement. The last time there was an altercation between one of these trucks and a commuter train the truck won.

Most of us around here give these guys lots of room on the road.

With regards to the very bad things that happen upon a sudden stop, that's actually a consideration with most heavy loads, such as refrigerated produce loads. If you end up walking it into the ditch and bury nose-first, all that weight is going to come through the cab in that classic "What's the last thing to go through a reefer-jock's mind when he noses in? His load." fashion.

But daaaaaayamn, one of those bastards cratered a train? Under normal circumstances, train vs. truck is about like truck vs. motorcycle.

I understand the economic incentive to reduce manpower, but at a certain point you can reach dimishing returns. Even if you reduce the frequency of accidents, accidents will still happen because
1) People make mistakes
2) Machines break
3) We can't control the weather
The higher the weight the larger the potential consequences of an accident. I also suspect that the greater the weight the more skillful the driver is required to be in order to handle it safely.

No argument there. As a former IC (independent contractor), I can tell you that another major factor of opposition was the fact that we didn't want to be putting that kind of strain on our tractors. Wear and tear on the unit comes directly out of our pockets.

Now, the one virtue would be in handling the weather, because the heavier the load, almost across the board the better the weather performance. Most people don't realize that the combination unit is designed to be operated under weight, and that an empty unit will actually take more distance to stop than a moderately loaded one, say at least ten tons in the box.

The engineering on trailers is actually pretty damned impressive. The springs are strong enough to handle over 48K in freight, but responsive enough that having somebody walking around in the trailer is actually something you can feel up in the cab.

As for skill level, eh, not really so much of a factor. Proper training should cover a the spectrum of weights handled, with an eye toward the different handling characteristics specific to weights, but that really boils down to two categories- light loads and really heavy loads. The main problem in that regard is that the state of training throughout the industry is frankly criminally negligent, IMO.

Personally, my take is that the weight limits are fine where they're at. The 80K gross and 53' trailer is the ideal truck freight distribution setup, and it's served well. The manpower issues that the industry is facing now should be solved by improvements in living conditions and wages, not by sticking more weight on trailers and for fuck's sake not expanding the usage of 57' trailers.

[Broomstick]

Then there are some basic physics problems with such a heavy load. For instance, if they front of the truck stops and, for whatever reason, the load doesn't (perhaps it was not adequately secured, perhaps the tractor encountered a solid object too suddenly, whatever) it pretty much squashes the driver and any vehicles for a good couple hundred feet in front of the rig. Needless to say, if one runs over you, you're dead. Accidents with these trucks have knocked down buildings and bridges. If the load falls off the trailer it tends to leave a 6-8 inch gouge in the pavement. The last time there was an altercation between one of these trucks and a commuter train the truck won.

Most of us around here give these guys lots of room on the road.

With regards to the very bad things that happen upon a sudden stop, that's actually a consideration with most heavy loads, such as refrigerated produce loads. If you end up walking it into the ditch and bury nose-first, all that weight is going to come through the cab in that classic "What's the last thing to go through a reefer-jock's mind when he noses in? His load." fashion.

But daaaaaayamn, one of those bastards cratered a train? Under normal circumstances, train vs. truck is about like truck vs. motorcycle.

Here's a good summary of the accident:

June 18, 1998
The first train of the day, Train 102 from Michigan City to Chicago, collided with a steel roll trailer left parked over the South Shore line while the driver waited for a passing train on the parallel Conrail line at Midwest Steel's main entrance. The NTSB estimated that the engineer had less than 6 seconds to react. Three passengers, including an off-duty South Shore employee, were crushed as the steel roll pushed through the first car, nearly reaching the center. Six others were injured of the 20 on the train that morning. The truck driver was cited for 15 violations, including being 70,000 pounds overweight, having malfuncioning brakes, and a trucker's log that was nearly a month out of date. He also tested positive for marijuana. The Federal Railroad Administration reduced rail speeds from 65mph to 40mph within 1.5mi of the crossings and banned trucks over 55ft long from crossing the rails. An overpass and the closing of Midwest's grade crossings are being discussed.

Let's just say there was a whole lot going wrong that morning.

It was fortunate this was the first train of the morning - a rush hour train would have had many more people aboard and the death toll might have been correspondingly higher.

And, by the way, the grade crossings by Midwest have been replaced by an overpass for the passenger trains.

The engineer of the train survived, by the way - when he saw he couldn't stop he threw the brake and ran up through the first car, yelling at people to get up and move. Probably saved a few lives that way.

Wish I could locate some good pictures on line - I remember the local newspapers ran pictures of the trashed rail car - looked like a tin can that had been stomped on by an elephant.