In that exact case yes, but I like to operate on the assumption that my trailer brakes are permanently broken. I’ve had them fail to operate mid-trip because they’re fucking trailer brakes.
Fn is proportional to the mass of the trailer, so it is irrelevant for the deceleration (a) if it is empty or not (because Ff = m*a).
µ is a constant relying on the tire/ground connection. Comparable to the towing car (if you happen to have car tire quality ones on your trailer, which might be doubtful)
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On top of that, typical car trailers use overrun brakes that per definition work by exerting an additional force on the towing vehicle in the direction of movement that is then used to activate the trailer brake.
Fair enough, car trailers do have garbage braking most of the time anyway. I may be biased because locomotives are so heavy and the traction you get with steel is shit so they actually benefit from some load behind…
I meant tailgaiting with your train ;-)
(but yes, I am aware of the systems that prevent that, heard some interesting talks about the topic and seen demonstrations in our local railway museum)
That is an oversimplified friction model that does not apply well to emergency braking. I still don’t think you get a better braking distance with a trailer in a typical situation but thats not the reason why.
It is my understanding that there are two types of brakes you’ll find on trailers, the ones activated by a weight that swings forward under the force of the truck’s braking, and electric ones. Neither are anti-lock or anything fance, and neither are really designed to provide actual stopping power, the drag they add is meant to help maintain control. Most of the braking force is done by the truck’s front wheels.
I don’t think it’s impossible for there to be a spot on the performance envelope where you’ll stop a few feet shorter with a lightly loaded trailer, but I bet it’s not particularly large.
There might be a way to load a trailer with perfectly spherical chickens and brake a certain way that maximized braking performance to… get a MythBusters result.
I assure you, that argument is exclusive to this forum, and wasn’t part of the dialog in the car at the time :-)
My idiot FIL, a chronic tailgater, the last ever time I opted to be a passenger.
If the trailer has very good brakes set to full power even when nearly empty, it’s actually true, but I doubt that’s the case…
I actually asked him that at the time
Glad you’re alive then.
Afterwards, had a quiet word to my spouse:
In that exact case yes, but I like to operate on the assumption that my trailer brakes are permanently broken. I’ve had them fail to operate mid-trip because they’re fucking trailer brakes.
I am pretty sure physics says “no”:
Ff <= µ*Fn
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On top of that, typical car trailers use overrun brakes that per definition work by exerting an additional force on the towing vehicle in the direction of movement that is then used to activate the trailer brake.
Fair enough, car trailers do have garbage braking most of the time anyway. I may be biased because locomotives are so heavy and the traction you get with steel is shit so they actually benefit from some load behind…
Locomotives? What is your profession?
In any case, I seriously hope that you are not tailgaiting ;-)
Freight train driver. I don’t tailgate, I like to leave plenty of distance in front of my car.
I meant tailgaiting with your train ;-)
(but yes, I am aware of the systems that prevent that, heard some interesting talks about the topic and seen demonstrations in our local railway museum)
That is an oversimplified friction model that does not apply well to emergency braking. I still don’t think you get a better braking distance with a trailer in a typical situation but thats not the reason why.
I could see where, if the trailer has good brakes and a relatively light load, it could provide additional stopping power.
That’s usually not going to be the case though.
I’m reasonably sure that you’ll never stop sooner, you’ll likely be exceeding the traction from the tires at that point anyway.
The trailer wasn’t braked.
It is my understanding that there are two types of brakes you’ll find on trailers, the ones activated by a weight that swings forward under the force of the truck’s braking, and electric ones. Neither are anti-lock or anything fance, and neither are really designed to provide actual stopping power, the drag they add is meant to help maintain control. Most of the braking force is done by the truck’s front wheels.
I don’t think it’s impossible for there to be a spot on the performance envelope where you’ll stop a few feet shorter with a lightly loaded trailer, but I bet it’s not particularly large.
It is impossible with a trailer with no brakes.
Hence the “stupidest thing” :-)
There might be a way to load a trailer with perfectly spherical chickens and brake a certain way that maximized braking performance to… get a MythBusters result.
I assure you, that argument is exclusive to this forum, and wasn’t part of the dialog in the car at the time :-)