| Author | Message | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A |
OK Class; If a coach chassis has a wheelbase of 258 inches and a track (width) of 78 inches and a planned large battery bank of 1250 pounds (total) is installed in the right front trunk averaging 58 inches behind the right front axle...... ......and averaging 24 inches outboard from the width centerline, how much weight is added to each corner of the chassis? This has been driving me CRAZY!!! Answer this and ya all go home for the weekend. Thanks. | ||
| dougthebonifiedbusnut (24.218.119.24)
Rating: N/A |
hey henry alot of weight on the right front corner alittle less weight on the leftr front corner far less weight on the right rear corner and the least weight on the left rear corner but why would you put that much weight outside the centrelineif you put it in the middle of the spare tire bay the front axle will absorbe most of the weight is the space just behind the end of the frame in the back available | ||
| jmaxwell (66.42.92.16) Rating: N/A |
On a slide-out or stationary mounted? Might tip the bus over if the slide comes out too far, or flatten the right front tire, or blow the right front airbag | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A |
Assumption, assumptions, assumptions, we are all making the wrong assumptions. Oh, well class, now you all must stay after school. He, he, he. What I failed to mention and what I thought (I assumed too!) did not require saying for this math quiz (I am LOUSY at math) is that the bus is a Crown Super Coach. No airbags. Simple leaf spring suspension. No slide out tray as access is great the way it is, no flatting the tire and NO full width trunk either, thus the 24 inch offset. Which is why the problem was stated as such. Yes, the right front will be affected the most, then the left front, then the right rear, then the left rear. The question I really need answering is HOW MUCH! Really need some help here if possible and I thank you for you help. CROWNS FOREVER!!! | ||
| Jim Ashworth (Jimnh) (172.130.151.18)
Rating: N/A |
OK Henry- here are the numbers. RF=674, LF=213, RR=276, LR=87. This is the increase due to the batteries only. Do something to offset this load when placing other items. Jim | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A |
To Jim the Math Whiz; Thank you, thank you, thank you!!! I feel soosss embarrassed NOT being to do this 6th grade math stuff. Even went to the library and looked thru math texts. No luck. How did you do it? What is your secret? Maybe it's because I am left handed or something. I know it deals with proportions and ratios and stuff, but the mind boggles. Well, my feeble mind anyway. And, I am afraid it gets even worse. Now add in a second fuel tank and a diesel gen set, plus holding and water tanks and other static and dynamic stuff..... .....and you get the idea. I will try to analyse how you did it and try to work out the rest on my own, or perhaps I'll just ask some kid to help me out. Oh well. And.....CROWNS FOREVER!!! Thanks | ||
| John Biundo (Jbiundo) (64.175.37.23)
Rating: N/A |
I second that motion! Jim, can you (easily) describe the calculations? I haven't really started load analysis yet, but I've been stewing on it a bit in the background. Also, are there "rules of thumb" about how one should distribute weight ideally with respect to center-line, axles, center of gravity, etc.? Thanks for any advice! John | ||
| Jim Ashworth (Jimnh) (172.157.185.157)
Rating: N/A |
OOPS. Minor corrections to above calculations. Fast fingers at the start will screw up all the rest of the numbers. Just ask me! Anyway, it is all weight and distance related. Calculate the ratio of the load front to rear. This gives total axle loading on F and R. Then take these calculated weights and do the same thing side to side. Using this example, 200" distance from rear (/) 258" wheelbase = (100%-78%)= 22% on rear axle and 58/258= (100%-22%)= 78% on front axle. With the 1250 lb load, this is 975 on the front axle and 275 on the rear axle. Then go side to side, the same way. 78" width (/) 15" in from right side= (100%-19%)= 81% on right side and 63/78= (100%-81%)=19% on left side. Take 19% of front axle load 975*19%= 185 on LF tire. Then do 975*81%=780 on RF tire. On the back, take 19% of 275 rear axle load 275*.19=52 for the LR tire and 275*.81=223 for the RR tire load. To verify, add (LF+RF+LR+RR) 185+780+52+223=1240 and the error is from rounding. Not difficult but make sure the first calculations are right since all others depend on them. AND, check your math  Sorry about the first post. John- Although the bus can level itself being way off balance, get the loads as balanced as you can. Be careful with the amount of weight put toward the front of the bus because the front axle is the weak point as far as load carrying capacity is concerned. Prevost has, on the XL model, 13500 on the front whereas the drive and tag capacity is 34,000 so you can see where most of the weight needs to be on a Prevost. My conversion, as purchased had 14500 on the front and 28000 on the rears. It is now 13200 on the front and 24800 on the rears. Before re-conversion, it would not come up to factory ride height on the front end, even with the air compressor set to 130psi. Now it does and can go well beyond when levelling with the airbags. Jim | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A |
To Jim Still The Math Wiz; Yea, I knew your first answer was not quite correct, but it was close and I did not want to rain upon your parade with all your help and stuff. I have been receiving some math instruction from a friend's 15 year old kid and it looks like I just might be able to figure this stuff out on my own. Eventually. Probably. Yea, Henry, in about 1000 years or soosss.... Jim, thanks again for your timely help in this matter. Is this math stuff explained in any do-it-yourself-bus conversion books? CROWNS FOREVER!!! | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A |
Oh, forgot to say that my Crown has the optional 16K front axle along with the usual 34K tandem drivers on the rear. The usual front end is 12K. GVWR is a huge 47160# and stripped she goes in at 23950# with 5000# on the driver's side front and 4400# on the passenger's side front for a total of 9400#. On the drivers she goes 7150# on the passenger's side and 7400# on the driver's side with half a tank of fuel and some various junk and stuff and me at 225#. Used a state scale. The coach is a little heavier on the driver's side than on the passenger's side, thus the plan of slightly offsetting the battery bank to even out the front end. Since I can only go to 14,600# legally on the front end and because hopefully the balance front to back will end up 30%F and 70%R, you can see some heavy stuff must go to the rear. Anyway, I may find out that the total balance may decide where the batteries eventually go. The plan is for a diesel electric coach-thus the huge batt bank. Thanks again Jim and everyone else. | ||
| John Biundo (Jbiundo) (64.175.37.23)
Rating: N/A |
Thanks Jim. john | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A |
He, he, he!!! Am I jazzed!!! Finally figured out this 6th grade math for getting the weights and balances of various stuff arranged around the coach chassis. Now can calculate various loads. Anyway....I THINK I understand it now. Actually pretty easy and super neat. Any weight, any location, with just a pencil and a cheap calculator anything can be figured. Thank you Jim and all the others. CROWNS FOREVER!!! | ||
| Tom Hamrick (Tomhamrick) (167.83.101.23)
Rating: N/A |
So how do you calculate the affect of adding weight in front of the front axle, or behind the rear axle??? | ||
| Henry R. Bergman, Jr. (Henryofcj) (63.224.197.10)
Rating: N/A |
Oh, that is soosss easy. I enjoy getting educated. It is sossss fun getting this old noggin to think and dink--even at my advanced age. Three days ago I could never do this. To answer your fine question, one just determines the ratio of the distance ADDED to the wheelbase of a given chassis. Not subtracted. Example---if a 650# gen set is to be mounted 72" behind the rear axle (extreme case) and the wheelbase is, lets say, 258 inches (same as my Crown 10-wheeler)... Then you add the 72" to 258" to get a total of 330"--then multiply 330 times 100 then divide that by 258 (wheelbase) and it gives you the total percent...(ratio) The gen set total weight on the rear axle, in this case equals 127.9% which times 650# equals 831# total on the rear end, which means the front end is lifted about 181#. Since the weight to be added is BEYOND the 4 corners the effect is of lifting one end and adding EXTRA weight to the other end. Does this make sense to you? Thanks. Henry | ||
| Tom Hamrick (Tomhamrick) (167.83.101.23)
Rating: N/A |
Thanks Henry, makes perfect sense to me. | ||
| Donald Ames (Donames) (67.242.33.68)
Rating: N/A |
OK Henry and Jim, I have a 4903 and I changed from the original 4 speed stick to an automatic. Then I added a beefed up class 3 hitch that I use to tow a 10,000# enclosed trailer with aproximatly 1K# tongue weight. The entire engine, transmision, and rear bumper /w hitch hangs from two bolts on angle iron from the roof of the coach. Am I in danger of droping the entire busness end of my coach on the highway near some dip in the road? Also in front of the drives the load is transfered from frame rails inside the wheels above the air bags through the bulkhead to the side walls of the coach. What is the added strain on this area? | ||
| FAST FRED (63.208.85.69) Rating: N/A |
"Oh, forgot to say that my Crown has the optional 16K front axle along with the usual 34K tandem drivers on the rear. The usual front end is 12K." If I understand the LAW the 12,000 lbs is the max the feds will let you drive with , any rating over that is AXLE rating , but not legal to put on public roads. However I have also heard of folks figguring the square inches under the tire and using higher loaded weights. Anyone know if that's legal , and how it works explaining it to the cops in the weigh station? FAST FRED |