Automatic transmission

The truck I'm driving now is a Volvo. The company has disconnected the manual mode so you have to deal with the annoyance of an auto. What I dislike about the automatics is that they are weak going up hill. They're not as good in the snow and backing under a trailer or up to a dock isn't as controllable.

The engine brake in an automatic is weak. Going down hill the engine brake doesn't hold you back as well and you can't lock it into a gear, at least not on this POS volvo.

 

That transmission has nothing to do with not being able to run up a hill. Almost all of those "automatics" are manual transmissions with pneumatic (air operated) servos that work the clutch and shift it. There is not really a lot of difference other than that. Even the 12 speed direct (detroit) is functionally the same as a 13 speed single over, but without that overdrive gear. They keep the engine RPM down by using fairly high rear end gears, like 2.62 or 2.2:1. As far as jakes go, yours might have a problem. I have driven autoshift cascadias in the past that had jakes powerful enough make unsecured crap slide off of the passenger seat.

 

And I drove a 2014 Volvo VHD with the D13 and i-Shift 12, and it could hold 80,000 lbs on a 10% grade at whatever speed the cruise control was set.

 

I always like to take folks that tell wide eyed stories about places like Cajon Pass, and Vail to some of the backroads in CA, PA, WV. And Ohio. A surprise 14% grade is real eye opener if you aren't ready for it. One of my favorite work arounds when the PA turnpike is jacked up is to take the skinny roads East out of Somerset. Pretty nice drive with not a lot of traffic. First time I ever went that way I was almost at gross in an automated Cascadia. Didn't have a problem. That #### DD15 will pull hard all the way down to 1000RPM.

 

Yeah I doubt a loaded truck will hold its speed on a 10% grade. The Coq is 8.5% and even the empty trucks will barely hold the speed limit.

 

The engine brake is rated for 500 hp at 2200 rpm. In addition, the VGT actuates as an exhaust brake on top of the engine brake's power. The engine itself was only 455 hp / 1850 tq.

Going 60 mph, it would kick down gears to get up to 2200 rpm, dropping 2 gears (maybe even 3, depending upon the setup). I'm no engineer as to how the system works, but it might also apply the regular brakes when needed to drop back speed to where it can control it, but I never once found it overwhelmed.

 

Are you talking about a pass in France? By the way, this is talking about going downhill not uphill.

 

Ah. Makes sense lol

 

No, you were right the first time. It's frightening how little understanding these guys have of what it takes to come safely of a grade. It's no wonder we see so many brake fires!

Think of the power requirements to achieve what they claim is happening. Take a hill that a 500hp truck climbs at 30mph, that's gonna be around 5.5 or 6 %. To come down that hill twice that fast requires 4 times that horsepower.

And an exhaust brake and a Jake don't add their respective hold back power. As the exhaust brake increases the exhaust manifold pressure, the Jake effectiveness drops its no longer dumping the cylinder pressure to near zero but only to whatever pressure the exhaust brake is generating.

Tl;dr: I wanna be there to see the show if he wants to come off the Coq at 60mph!

 

Most useful observation so far about speed.
My average was 60 mph with a top speed of 75mph.
All the rest is just noise.