Measuring the Gradeability of a vehicle

Blooming Flower · 26th December 2019, 16:21

Most of us, perhaps, know and understand what the terminology ‘Gradeabilty’ purports in 4x4 world. But what intrigues me somehow is how it is calculated for a vehicle. To rephrase it, what are the parameters taken into consideration for objective calculation of this value? Does this objective value correlate fairly in practical situation?

I thought of bringing this into a new and separate thread as the discussion was digressing from the intent of a particular thread given below.

https://www.team-bhp.com/forum/elect...ml#post4719550

Experts, please pitch in with your knowledge.

venkyhere · 26th December 2019, 17:48

found this :
http://www.thecartech.com/subjects/a...x_gradient.pdf

explains with simple physics, how 4WD is better than RWD is better than FWD, in climbing up slopes. Also, how increasing GC helps RWD to climb, while decreasing GC helps FWD to climb.

still it doesn't explain how some offroaders are able to climb more than 45 degree slope (with the theoretical assumption that 'u' can only be <=1)

Blooming Flower · 26th December 2019, 18:11

Indeed, quite a good mathematical explanation is furnished in the document you shared. But as it is said and you too agree that the gradeability of a car cannot go beyond 100% i.e. 45°, what about the following image? Obviously, it doesn't violate basic principles of physics. But what is the right explanation then and what are the exhaustive parameters to take into account for calculating the real figure?
Name: Moab_Hummer.PNG
Views: 3576
Size: 179.7 KB

Name: Moab_Hummer.PNG
Views: 3576
Size: 179.7 KB

Edit:The highlighted part says 60° slope. (It is almost masked by Team-bhp logo)

shankar.balan · 26th December 2019, 18:22

Very interesting inputs, especially for those on the forum who live/ drive in the hilly terrain of India. This will help us to learn what climbs ought to be attempted in the different cars we drive and what climbs we ought never to attempt!

GTO · 27th December 2019, 13:53

A useful post from Spike Arrestor:

Quote:

Originally Posted by SPIKE ARRESTOR

Milecruncher, i have explained Gradeability in detail here:- http://www.team-bhp.com/forum/4x4-te...ulation-3.html The percentage generally is nothing but the slope, a percentage of 100 means slope or tan theta=1, which means gradeability or theta=45 degrees, similarly gradeability=80% means tan theta=0.8 hence gradeability or theta= 38 degrees. Normally vehicles are designed with upto 70% gradeability. Trust this helps. Spike

26th December 2019, 16:21	#1
Blooming Flower BHPian Join Date: Apr 2017 Location: Pune Posts: 255 Thanked: 1,135 Times	Measuring the Gradeability of a vehicle Most of us, perhaps, know and understand what the terminology ‘Gradeabilty’ purports in 4x4 world. But what intrigues me somehow is how it is calculated for a vehicle. To rephrase it, what are the parameters taken into consideration for objective calculation of this value? Does this objective value correlate fairly in practical situation? I thought of bringing this into a new and separate thread as the discussion was digressing from the intent of a particular thread given below. https://www.team-bhp.com/forum/elect...ml#post4719550 Experts, please pitch in with your knowledge.
	(5) Thanks

26th December 2019, 17:48	#2
venkyhere BANNED Join Date: Mar 2011 Location: hump city Posts: 1,293 Thanked: 5,861 Times Infractions: 0/1 (7)	re: Measuring the Gradeability of a vehicle found this : http://www.thecartech.com/subjects/a...x_gradient.pdf explains with simple physics, how 4WD is better than RWD is better than FWD, in climbing up slopes. Also, how increasing GC helps RWD to climb, while decreasing GC helps FWD to climb. still it doesn't explain how some offroaders are able to climb more than 45 degree slope (with the theoretical assumption that 'u' can only be <=1) Last edited by venkyhere : 26th December 2019 at 17:52.
	(6) Thanks

26th December 2019, 18:11	#3
Blooming Flower BHPian Join Date: Apr 2017 Location: Pune Posts: 255 Thanked: 1,135 Times	re: Measuring the Gradeability of a vehicle Indeed, quite a good mathematical explanation is furnished in the document you shared. But as it is said and you too agree that the gradeability of a car cannot go beyond 100% i.e. 45°, what about the following image? Obviously, it doesn't violate basic principles of physics. But what is the right explanation then and what are the exhaustive parameters to take into account for calculating the real figure? Edit:The highlighted part says 60° slope. (It is almost masked by Team-bhp logo) Last edited by Blooming Flower : 26th December 2019 at 18:13.
	(4) Thanks

26th December 2019, 18:22	#4
shankar.balan BANNED Join Date: Apr 2008 Location: Bangalore Posts: 11,368 Thanked: 23,150 Times View My Garage Infractions: 0/2 (8)	re: Measuring the Gradeability of a vehicle Very interesting inputs, especially for those on the forum who live/ drive in the hilly terrain of India. This will help us to learn what climbs ought to be attempted in the different cars we drive and what climbs we ought never to attempt!
	(1) Thanks