Uphill Shifting

I personally go high so it drops to where I need it when I shift. Honestly not sure if that's the right way...just the way I do it.

 

I usually keep my CAT at 1650 uphill , when dropped to 1475 - downshift again .

 

...detroit probably needs higher rpms , also depends how heavy and how steep the hill is ... Cummins probably lower

 

Upshifting bring it to the top and hold for a couple seconds, watch the speedo, once it levels off shift.

Downshifting don't let it get to the bottom, give yourself some room to work with. When it will hold speed in the middle of the torque curve without having to mash the throttle all the way down, hold until ya get to the top.

 

Detriot will work hard not to quit a gear close to the bottom of torque. Then you will have to shift. Cummins you wind em out and they will take the next gear down somewhere half way towards bottom of Range. But Cummins is a one speed engine, not known for mountain work. CAT you can come down until you have to downshift.

You will know when your rig wants the next gear down and you need to make it happen before she lugs and starts to buck on you. If you make a hash of it upgrade then you will need to start all over again. At some point shes going to settle into one gear until the top and thats all you get.

Most big horse trucks today will cruise upgrade not far from the speed limit at 80000 pounds believe it or not on most common grades like 5 to 7% They will give up a few gears and generally up and over without too much combat with downshifting.

If you ever face grades off interstate system in excess of say 13% at Luray or maybe 21 to 24% in Vermont etc you will end up in a low range gear and you do not dare leave it until the top. Falling backwards down is a killer for all involved.

anyone can get up and over. Its the getting down is what separates men from boys.

 

Edit: Im a Durrr

 

I would shift at 1600 if you have to keep it in that range of rpm but how big is the hill?

 

That depends on the engine.

Let's get down to basic.

If your Engine is torque at 1350 RPM and starts to buck and jerk fighting you below 1200 then you know it's time to shift at 1400 before it falls too far upgrade.

Rev to about around 1800 if you have that much tach room and get the next gear down, this puts you between redline speed (1950) and high horsepower curve call it 1600 She will pull down against the upgrade dropping RPMs until she either stablizes in that gear upgrade in one speed until the top (Provided the mountain does not steepen in places) or she is back to 1400 and falling. Thats time to get another gear down.

There is a balance between your power, mechanical advantage conferred by your reduction in the transmission against gravity and your total weight. And you will reach that balance and find she will pull say... 1500 in 7th at about oh 40 mph upgrade until top.

When you get over the top, you will have to set up the truck to do everything backwards and get ready to set up the jacobs braking against the downgrade so that you are stable all the way down without touching your brakes. Your brakes stay cold ready for battle should you have need of them. For example the fuse box connected to your jacobs viberates loose or burns out leaving you on sustained braking until the bottom. With cold brakes you have an advantage.

There are grades out here that are absolutely dangerous. You will say sit at a stop sign and see nothing but sky. Your hood blocks the highway you are trying to lift out and onto for a turn. This is where you pick granny low and stay in it all the way through the turn until your trailer is OUT of that hole and your turn is finished. The traffic will have problems (Google earth Tuscarora Md near the US 15 river crossing, about 1/4 mile above the bridge you will see a example of such a steep pull out onto a divided highway with it's own grades.

If you are on a steep grade say 13% running Luray VA, then whatever gear your tractor falls into after you downshift fast until you find say 6th or even 5th and she will settle and pull it. Slowly. But she will pull it. The big thing is not to floor it or redline it. You might burn something out and cause a stop which is very dangerous to you and everyone below you. Some grades are so steep you are in granny low at less than walking speed. Actually crawling with the wheels barely turning. Just keep calm and stay in whatever gear she is in somewhere around 1400 or 1500 or so.