This seems counterintuitive. I would love to hear why.
Most of a tractor-trailer's stopping power is split between the trailer brakes and the tractor's drive tandems. If there is not enough weight on those axles, the tires can't grip the pavement properly. If I apply too much power to the brakes the wheels can start bouncing or just lock up and start skidding if the ABS system is acting up.
Most tractor-trailers you see on the road in the US are designed to weigh 60,000 to 80,000 lbs (~ 27,000 - 36,000 kg). For comparison, a Honda Civic weighs roughly 3,000 lbs (1360 kg). Every system on the truck is designed around moving that amount of mass safely. With an empty dry van trailer your looking at closer to 30,000 lbs (~ 13,000 kg). Makes a difference in performance. Ride is rougher, takes longer to stop.
Thank you. That's fascinating.
Sounds like you’re talking about icy or wet roads. I’ve never had a trailer do that on dry pavement and I can definitely stop faster emptying than full.
I really wish that were entirely the case. The distances I quoted came from safety trainings I’ve had to take over the years. Given my personal experiences during that time, I think they were from before ABS was mandated. And I had a lot of ABS failures when I was OTR and few close calls as a result of those failures. That’s one of the reasons I chose to switch to running a yard truck 5 years ago. Far less stress.
When ABS failed on dry pavement and I needed to stop in a hurry, the affected tandem would tend to lock up and bounce along the ground. Nerve racking and scary when there’s traffic in front of you, but not near as bad as on wet or icy roads. The sheer terror of feeling one of my axles start sliding under me.
If I had one word of advice for drivers new to the industry, it would be to drive as if none of the safety systems on the truck and trailer exist because in my experience they will fail exactly when you need them.
I would imagine it has to do with traction and ability to apply braking forces without skidding the wheels.
Even in a pickup truck, it's easy to skid the rear wheels (antilock brakes aside) with the bed empty because the brakes can easily overcome the traction of the tires. This is why pickups have height sensing proportioning valves.
This seems counterintuitive. I would love to hear why.
Most of a tractor-trailer's stopping power is split between the trailer brakes and the tractor's drive tandems. If there is not enough weight on those axles, the tires can't grip the pavement properly. If I apply too much power to the brakes the wheels can start bouncing or just lock up and start skidding if the ABS system is acting up.
Most tractor-trailers you see on the road in the US are designed to weigh 60,000 to 80,000 lbs (~ 27,000 - 36,000 kg). For comparison, a Honda Civic weighs roughly 3,000 lbs (1360 kg). Every system on the truck is designed around moving that amount of mass safely. With an empty dry van trailer your looking at closer to 30,000 lbs (~ 13,000 kg). Makes a difference in performance. Ride is rougher, takes longer to stop.
Thank you. That's fascinating.
Sounds like you’re talking about icy or wet roads. I’ve never had a trailer do that on dry pavement and I can definitely stop faster emptying than full.
I really wish that were entirely the case. The distances I quoted came from safety trainings I’ve had to take over the years. Given my personal experiences during that time, I think they were from before ABS was mandated. And I had a lot of ABS failures when I was OTR and few close calls as a result of those failures. That’s one of the reasons I chose to switch to running a yard truck 5 years ago. Far less stress.
When ABS failed on dry pavement and I needed to stop in a hurry, the affected tandem would tend to lock up and bounce along the ground. Nerve racking and scary when there’s traffic in front of you, but not near as bad as on wet or icy roads. The sheer terror of feeling one of my axles start sliding under me.
If I had one word of advice for drivers new to the industry, it would be to drive as if none of the safety systems on the truck and trailer exist because in my experience they will fail exactly when you need them.
But when they do work they are f-ing magical.
I would imagine it has to do with traction and ability to apply braking forces without skidding the wheels.
Even in a pickup truck, it's easy to skid the rear wheels (antilock brakes aside) with the bed empty because the brakes can easily overcome the traction of the tires. This is why pickups have height sensing proportioning valves.
That makes sense.