Maxed out truck can't climb a hill faster than 20mph

[Brigsworth]

I'm in a Peterbilt 389 with a 625hp engine and an Eaton 18, climbing a mountain into Denver hauling 171,000lbs.

I can't shift past 9th gear or surpass ~20mph when the hill is super steep. Is this expected behavior or am I doing something wrong.

[draco.klingon]

You are right. It looks like it is a little bit too fast! ;-)



Sorry for that joke! Look at the amount of your load! Your truck is all, but not empty!
Maybe you didn't feel the load or the % you climb up, but I guess all fine if you reach 20mph with that load!

[Wolfgang]

That is to be expected by the laws of physics. Gravity is against you and your cargo wants to follow gravity.

Or in a more science-like manner (or being nerdy):
Your engine needs to make enough energy through combustion so that you and your truck can get upwards i.e. increasing your potential energy (E=m*g*h). At the same time you want to drive forward using kinetic energy (E=0.5*m*v^2). As your speed upwards is a vector (you drive forward and upwards at the same time) only parts of the energy from the engine is going into your forward momentum (which is horizontal movement) and the rest goes into increasing your potential energy (or moving upwards). This means you will move forward as long as your engine can deliver enough energy to get you upwards.
(And there are also the things of slopes and friction but that would go to far now.)

[CaptainNebulous]

171,000 is a pretty heavy load. 20MPH sounds about right climbing up those mountains surrounding Denver with that load. If you watch any real life truckers from that area on youtube you'll find that this is actually pretty realistic. There is also many flat and downhill sections in that region that you'll flat out wreck if you go much faster than 20 with a load of that size.

[mr_bman]

It goes by torque. Try to keep your RPM's at where your max. torque happens - 1100-1200 rpm for most of them. An 18 speed is good on hills because you can keep your RPM's closer to where your max torque is.

[RileyKittendorf]

Sweet jesus they are worked hard if that's anything like RealLife

[Sgt. Tibbs]

Yea...That's real life..I must say they got that right... I'm Retired CDL ..20 yrs. OTR and I cut my teeth in the Rocky moutains!

[Ghostrider]

Also there are times in real life where if the load is really heavy and the hill too steep.. They will hitch up another prime mover to either the front, or back to provide that extra power to allow the load to get to the top of the incline..

[LarryA]

RL Out of Mile High 40+ Years I 70 West. Is a 7% Grades Genesse, Loveland, Vail. In ATS I 70 W About 4%_5 1/2%. "Not" a full 7% Grade...

359 Pet e: 1974: 1693 TA Cat 475 H.P.. 6 & 4 Double Under. Rear end Ratio 4:56. 6th over @ 1800 RPM. 64 MPH.

CDOT.. GVWs: Axel Weight 20,000 Steer Axel_36,000 Twin Screw. Interstate. State_County Roads 90,000 GVW. Per Bridge Law Requirements...
1. 73,280_80,000 45 MPH Have to back out to 40 MPH Drive tires get to "Hot" IN Summer.
2. 100,000 35_40 MPH
3. 200,000_250,000 30_35 MPH
4. 250,000_300,00 25_30 MPH

Number 5. "Pusher Truck "No". Rear ends over heat Yes 10w_30W Motor oil_Pumps Installed in the rear end housings. Lubricate axel bearings Ring & Pinon... Re build rear ends 650 Miles Required. Get to "Hot" bearings burn up. Actualy burn the paint off the housings. Smoke "Yes". Primarily 7% Grade Down Hill. 380 F + @ 8 MPH. Cat Brake Saver 45 LBS oil pressure. Engine Oil Temp 220 F..

5. 565,000_585,000 7 MPH_8 MPH Pusher Truck "NO". GVW. Empty Weight: 185,000. Estimated GVW 585,000 + or - a few 1000 Lbs..Could "Not" axle load on scales or weigh at Downeyvill, co. CDOT "Not required"...Couldnt get on scales anyway. To Long_To Heavy...

HH Loads consisted of Heavy Equipment to various destinations. Bridge Gerders to Glenwood Canyon.

Typically you cannot Permit HH and or Hazmat loads thru the tunnel per CDOT. Note Lights at tunnel. Electric Eye plus siren. Hazmat must run over top of Loveland Pass US 6. ATS Ramps Yes. US 6 Over "No". Restrictions: No loads over 13 ft 6 inches or over 102 inches wide _65 Ft Long.

Edit: Only Exception: Bridge Gerders 205 ft_220 Ft Long Gerder Weight. 1800 LBS Per Ft.. Glennwood Canyon out of Mile High_Eagle Layover 12 Hrs. Eagle_Glennwood Canyon_6 Hrs... "Closed" Tunnel @ 4:00 A,M. for one hour...Monday thru Friday...

Have A Greaty Day