Hey guys, I am having some problems with the Caterpillar Performance Handbook. I don't understand some things. First, on the "Effective Grade" Charts (Grade Assistance minus Rolling), what if I have a grade assistance of 2% and a rolling resistance of 4%?? I get -2%, how do I do that?? Also according to the way to do that a steeper grade would be a higher Total Resistance, how is that, more retarding?? I have some more questions, but lets take care of that one first.
Nolan Treat roling resistance like it is a negative, and grade assistance like it is a positive. Assistance of +2% and resistance of -4% equals a total resistance of 2%. Your answer is correct, just think of resistance as always negative, as it always slows you down. When you start figuring this, you will only ever get close, as conditions on most jobs change often enough that you need to figure an average. You could take a full year course, and still not cover all the variables on cycle times.
Jerry, Thank you for your reply. What are you doing to get 2% from 2% and -4%?? Can you give me some more example problems so I understand it better to?? In the examples how about have some that are Grade Resistance to. And wouldn't a steeper grade help the machine going downhill?? Also what do you do if you have Total Assistance, if there is such a thing?? Example, your rolling is low and grade assiatance is high. After that I will proceed with my other questions everyone.
Nolan It is really -2%, but as I said before, resistance is always a negative effect, so standard practice is to simply call it resistance, then the "-" sign is redundant.
Thanks Jerry. I understand it now. That clears that up. Next question gentleman. On the "Rimpull-Speed-Gradeability Curves" charts I seem to get slower speed for empty machines than loaded. I followed the example they give you, but if you do the same exact problem empty you get the same speed. And in some situations like I said you get slower speeds on empty than loaded, why is that, or what am I doing wrong?? Same goes for the "Retarder Curves" charts.
Best check with your Cat dealer PSR guy for more answers to questions regarding charts and graphs in the Cat handbooks. He will have all the answers for you, or he will check with the factory and get back to you in short order. That's if you aren't running a bunch of Komatsu's or Volvo's.
Welcome to HEF surfer-joe! :drinkup
could you send me this manual , please ? [email protected]
I don't have a copy of the manual online. I only have the hard copy.
I'm probably way off, but I think a big part of the reason for that Nolan is that extra weight. On trucks for example the drive wheels (or 2/3 of them on ADT's) are under the bed of the truck, so when they are loaded you have more weight pushing down to give added traction effort, course if you're on some soft spongey crap you just sink.:Banghead