Thread: turning radius
02-05-2001, 11:23 PM #1John Berryman Jr.Firehouse.com Guest
On the subject of turning radius of differant wheel bases & wheel cut angle.Is there a formula?? I have two units one with a 206 wb/50degree wheel cut tires 22'5 and one with a 215wb/45deg.wheel cut 22.5 tires.I need to know how much space they will take up in a turn.. Any help or advice would be great
02-06-2001, 12:10 PM #2mike021Firehouse.com Guest
Did you try calling the manufacturer? Or check the specs they should have the radius and everything in the specs. I know Pierce does that.
02-06-2001, 04:19 PM #3SBrooksFirehouse.com Guest
the Society of Automotive Engineers (sae.org) has a method to calculate the turning radius, however when I looked a year or two ago, the pamphlet was $50 or so. I keep meaning to check and see if the local college library has it.
02-14-2001, 12:12 PM #4DN GreenfeldFirehouse.com Guest
There is one more variable to take into consideration. That would be wether tires are 10R or 11R.
10R/22.5, 206WB, Turning radius would be approx. 28 feet with curb to curb of 56 feet
10R/22.5, 215WB, Turning radius would be approx. 30 feet with curb to curb of 60 feet
11R/22.5, 206WB, Turning radius would be approx. 27.5 feet with curb to curb of 55 feet
11R/22.5, 215WB, Turning radius woudld be approx. 29 feet with curb to curb of 58 feet
Hope this is helpful.
02-14-2001, 02:45 PM #5N2DFireFirehouse.com Guest
O.K. - I'm not ashamed to admit when I'm licked.
DN Greenfeld - what formula or equation(s) did you use to come up with those answers ??
The ONLY formula I could come up with (after several days of searching) was one to find the steering angle based on a desired turning radius and a given wheel base which I then transposed into the following :
Turning Radius = (wheel base / tan(steering angle)) - wheel track/2
WB t TR = ------ - - tan(SA) 2
Saddest part of all is that about 7 years ago I recived an AAS Degree in Mechanical Engineering Technology - I should have been able to figure this one out (Too many years of being a computer programmer instead of an engineer I guess).
PLEASE put me out of my misery and give me the equation(s) you used.
Take Care - Stay Safe
[This message has been edited by N2DFire (edited 02-14-2001).]
02-14-2001, 03:09 PM #6SBrooksFirehouse.com Guest
I imagine there are things to consider such as tire scrub, etc.
I would think that tire size would have a greater effect on cramp angle than it would on tire scrub.
also look into "ackerman steering"
02-14-2001, 05:49 PM #7DN GreenfeldFirehouse.com Guest
I didn't use a formula, just the Freightliner refernce guide.
02-15-2001, 02:23 PM #8DonRobbieFirehouse.com Guest
03-02-2001, 03:58 PM #9SBrooksFirehouse.com Guest
Here's a doozy:
TR = SQRT[(wb/tan(sa)+t)^2+wb^2]
where wb = wheelbase
sa = steering angle of inside wheel
t = wheel track
TR = turn radius
make sure all units are the same (all feet or all inches)
formula doesn't account for different tracks, front & rear. It doesn't make much of a difference.
By the formula:
Custom Pumper: 180" wb & 45 deg sa, TR = 27'
Commercial Pumper: 199" wb & 50 deg sa, TR = 27'
Meritor's new 55 deg axle = 217" wb, 27'TR
Note that the 45 degree wheel cut is more than we've gotten in many years...most of our older (more than 5 years) wagons probably have somewhere between 40-45 degrees. Unless you've got interference with a front intake.
03-02-2001, 06:34 PM #10RJEFirehouse.com Guest
Yeah, tell me about it. Try your formula on my new Pete tractors. 260" wheelbase, 96" track, and 39 degree wheel cut.
You guys have it easy. ('course, that's why I don't drive anymore, either)
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