Rimpull calc's 6

[metman]

I would post at mining engineering if we had one here at eng-tips

New job – first week

My boss’s boss, John - exec VP, is not an engineer but he has designed some of the equipment we build. John worked his way up from welder/fabricator. He told me to research Rimpull and said, “Minimum hp for a mining truck is based on Rimpull requirements for the mine.”

Later, my boss turned to page 8-13 in Edition 39 of Caterpillar Performance Handbook hardcopy on-hand (Page 8-19 in Edition 40 pdf file) to show me where to find Rimpull. There are other pages that explain the USE OF RIMPUL-SPEED-GRADABILITY CURVES.
This USE OF… explanation does not make sense to me so I am hoping to find another more basic explanation.

I don’t see anything on those pages about hp but there must be some way to correlate it.

After work tomorrow, Saturday, I plan to research at the local library hard copy/interlibrary and online to see if there is a more detailed explanation than what is in the CAT book. It would seem like CAT would have as good or better handle on this than anyone but because they are the expert’s maybe they jump over some other basic stuff they expect the user to know.

I have a pdf of above given page 8-19 and I know how to take a snapshot but do not know how to attach here but will try later.

meanwhile -- more basic explanation somewhere, anyone?

 

[metengr]

forum454

 

[metengr]

http://www.scribd.com/doc/25947612/82/Rimpull-Speed-Gradeability-Curves

http://books.google.com/books?id=We...HHKQ&hl=en#v=onepage&q=RIMPULL curves&f=false

 

[MintJulep]

It would be nice to see the derivation of dimensionless "TR" term.

I don't quite see how "Total Resistance" can be dimensionless.

I suspect it must be pounds of resistance per pound of vehicle weight.

 

[Ron]

Check Construction Equipment, Methods and Procedures by Robert Peurifoy.

 

[zekeman]

Rimpull is gross weight times effective grade
Power is speed*rimpull.

This is borne out by simple physics and the curves,

HP = Rimpull *mph * k

I think you should be able to find k.

Looks fairly straightforward.

 

[IceStationZebra]

"Total Resistance" is shown as percent loss. The number is the sum of the percent slope and percent rolling resistance. Working with "percents" makes it easy to calculate the rim pull. (i.e. X% TR means you need a minimum rim pull of X% of your GVW)

example: 10% slope + 3% rolling resistance = 13% TR
1,000,000 lb GVW * 13% = 130,000 lbs rim pull
For a CAT 793C this would give a max speed of ~6mph.
(note that this is ideal, you may need to account for altitude derate, engine wear, etc.)

Procedure:
1. find the truck GVW on the top scale.
2. drop a line down until you hit the appropriate TR line
3. draw a line horizontally to your left axis, this gives you the minimum rim pull needed.
4. drop a line down to the bottom axis from where the horizontal line you just drew crosses the speed curves. This gives you the maximum speed you can attain.

ISZ

 

[MintJulep]

Alright, it's just a balance speed calculation.

Resistance is grade + rolling resistance.

Grade resistance is slope X gross weight.

Rolling resistance is a function of weight and speed.

Motive effort is engine torque, gear ratio, tire diameter and engine RPM.

When total resistance = motive effort there is no excess engine umph available for acceleration and that's the balance speed.

 

[metman]

Thank you, each and every one of you. Just scanned all of your replies and it appears that every response will help me in some fashion to get my mind around this topic.

I did not get to the library in time yesterday but expect to make it today, Sunday. Fortunately it is a college town and in a mining area so some of the books on Metengr's links very possibly will actaully be there. However I will first try some of the basic suggestions you folks provided along with the CAT book.

My friend, Joa, is an Aeronautical Engineer PE, DAR, DER etc etc very lettterd - eh. He agreed to help me with Rimpull and was supposed to meet with me last night but could not make it so then he was supposed to call this morning but has not. Therefore your help here is magnified greatly in importance to helping me.

This new job is extremely fascintaing. It will require me to draw upon every bit of my engineering and shop experience. Sorry that I cannot divluge any details. I am ecstatic not only to get a job in these times but the best job I have ever had.

metengr, where did you find the folloeing forum? Is it
somewhere here in eng-tips?:
forum454: Mining engineering other topics

Joa just called and we will meet shortly!!!

 

[dhengr]

Metman:

My compliments...; it’s encouraging to hear about a fellow engineer who’ll still go the library to learn something, instead of only taking the easy way out by coming to a forum and hoping he gets good and factual answers. At the same time, I’m not suggesting that there isn’t a lot of good engineering advice being given on E-Tips or in this thread. I just like your extra effort to dig for the info. It’s also good to hear that you are using your friend Joa as a mentor or for help if he is more knowledgeable on the subject. Those face to face interactions are almost always more meaningful and more long lasting, than trips to the easy answer store.

Also, ask your boss and John for help and to be your mentors. They should be truly interested in seeing you learn, ultimately it makes them look better too. That kind of equipment is fun to design, build and work on. John may not be an engineer but it is amazing what you can learn from those older fellows who learned what they know the hard way. We can learn practical things from them that we would never get from school or a text book.

 

[vpl]

metman,

In regard to where metengr found the forum -- if you go to the very top of the page, above the ad, by the search boxes, there is a dark blue box that ssys "forums." Clicking on it, will give a list of several options -- one that you might find interesting is "Browse forums," another is "forum list."

However, you should just be able to click on the link in metengr's post, which will direct you to the forum -- and after which it will be added to your Threadminder.


Patricia Lougheed

******

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[metman]

dhengr, Thanks for the compliment and now that I have a job I will be contributing more financially to tips.

Ron (Structural)
Do you know of a library that has this book?

Construction Equipment, Methods and Procedures by Robert Peurifoy. There was a copy(ies) on line for $163 so before being bought, I wanted to see if I could do an interlibrary loan. At a local library, I asked the research librarian to check with:
• Missouri School of Mines
• Carnegie Mellon U.
• Colorado School of Mines
• Lewis and Clark State College
• U of Idaho

but no luck

...it is amazing what you can learn from those older fellows who learned what they know the hard way.

Yes I have much respect for this. My Dad was a self taught mechanical engineer. He invented, designed, and built a very succesful "donut turner", worked on designing a stair climbing wheel chair for 25 years with many novel ideas including a roller chain that activated a device by PUSHING on the chain. I wish I had inhertited a tenth of his creativeness but one of the things things that I learned from Arthur Mudge's Value Engineering is that we can improve our ability to be creative. One of my Dad's brother's was a self taught Architect.

You also might be interested to know that I am one those old geezers. I must be 'cause I have false teeth, false eyes, and false ears. Not only that but I have Sebbaria Karitosis which is not uncommon in men over 80 yrs but I am ONLY 71 yrs. Still playing tennis regular and loving this job. We have an empty warehouse attached the office that I am in which will not be used for months so our CEO turned it into a temporay homeless shelter two days ago. It just keeps getting better and better.

If I were doing any better, I would have to be triplets because I am already beside myself.

 

[metman]

MintJulep,
I think IceStationZebra answered your question but you have most likely figured that out yourself.

An lps for all of you.

 

[metman]

Ron (Structural) 18 Nov 11 19:15
Check Construction Equipment, Methods and Procedures by Robert Peurifoy.

Yesterday, Sunday, a different research librarian was on duty and found the following book with a slightly different title which I suspect is why the other librarian could not locate it:

Construction Planning, Equipment and Methods

It was near closing time at the library so she was probably a little more officious/abrupt than normal not telling what library etc just that I had to show evidence of permanent residence before she can put a hold on it --maybe it is right there in her library? In any event, last night I moved into a home as a roomate and a friend will mail me a letter today for proof of residence so I can get a real library card instead of temporary.

Now I will look at metengr's links

 

[Ron]

Metman...that's the correct title. I was working off memory. I have had the book in my library for over 30 years. Purchased a later edition a few years ago.

It's a pretty good reference, but $163 is a bit steep. I checked Amazon.com and you can get a 7th edition (2005) for as low as $25. That should be sufficient for your purposes.

 

[metman]

Ron (Structural)
Yes I figured you were depending on memory.
Thanks loads. I'm going for it but will have someone else order for me. I am an idiot trying to buy off the net. I got flamboozled out of $700 trying to buy a Vertical metal cutting band saw on ebay a few years ago so I am gun-shy. It must be the geezer syndrome!

I love eng-tips

 

[metman]

Ron (Structural)

Today I received the book that I ordered online, i.e., Construction Planning, Equipment, and Methods Seventh Edition by Robert L. Peurifoy, Clifford J. Schexnayder, and Aviad Shapira.

Inside of 10 minutes I found the answer to my question on page 235 under Step 2: Rolling Resistance.

The CAT Performance Handbook does not delineate that RR is an either/or factor. Is that what I get for being overqualified (no brag just complaining, CAT guys actually said that when we met over the phone and heard my background) -- can’t understand the simple stuff?

The book is in excellent condition, only cost $17 including shipping, and will be useful for other similar subjects.

A few minutes ago the library called with the interlibrary loan here.

Cheers (in every sense of the word)


Design for RELIABILITY, manufacturability and maintainability