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Old 22nd September 2008, 18:46   #1
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Default Basic 4X4 Terms

Hello to all Team-BHP Members.

I am attaching a simple, but useful terms & parts description document regarding 4WD Vehicles. This document includes meanings of terms like ramp break-over angle, AWD, engine breaking, rebound, viscous coupling to different parts meaning like C-Section Chassis, torsion bars, LSD, UV-Joints etc.
It may be known to many of you, but still I think it can be useful to other newbies like me.

@Mods: Pardon me if something like this is already posted in some other post & I missed it. Please post this to appropriate thread if already existing.

Thanks & Regards,
O_M

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Source: Offroad Terms
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Last edited by Samurai : 23rd September 2008 at 00:37. Reason: source not mentioned
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Old 22nd September 2008, 22:06   #2
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@offroad_maniac: truly informative document. thanks.

BTW, what is 4L & 4H ? gurus, please throw some light.
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Old 22nd September 2008, 22:25   #3
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Originally Posted by badboyscad View Post
@offroad_maniac: truly informative document. thanks.

BTW, what is 4L & 4H ? gurus, please throw some light.
@ badboyscad..hope this helps, as simple as i could make it..

2H = 2wheel high gearing. Normal rear-wheel drive. Use this with normal driving on tarred roads and dry sand roads. Never drive faster than 100 km/h.

4H = 4wheel high gearing. Normal 4-wheel drive. Use this on muddy and slippery sand roads. Never drive faster than 60km/h. This should be enough to travel to most areas.

4L = 4wheel low gearing. 4-wheel drive for very extreme roads. Slow speeds. Short gears.
Used to navigate difficult and poor terrain whereby you cannot travel more than 30km/h.

Quote:
Originally Posted by offroad_maniac View Post
Hello to all Team-BHP Members.

I am attaching a simple, but useful terms & parts description document regarding 4WD Vehicles. This document includes meanings of terms like ramp break-over angle, AWD, engine breaking, rebound, viscous coupling to different parts meaning like C-Section Chassis, torsion bars, LSD, UV-Joints etc.
It may be known to many of you, but still I think it can be useful to other newbies like me.

@Mods: Pardon me if something like this is already posted in some other post & I missed it. Please post this to appropriate thread if already existing.

Thanks & Regards,
O_M
nice one @ offroad_maniac

Last edited by Rehaan : 24th September 2008 at 02:20. Reason: Posts merged. Please use the MULTIQUOTE button.
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Old 22nd September 2008, 23:24   #4
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Quote:
Originally Posted by badboyscad View Post
@offroad_maniac: truly informative document. thanks.

BTW, what is 4L & 4H ? gurus, please throw some light.
4L = four wheel drive low ratio selected through transfer case.
4H = four wheel drive high ratio selected though transfer case.
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Old 22nd September 2008, 23:33   #5
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@ruffryder@ & anshuman: very crisp and clear explanation, thanks.
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Old 22nd September 2008, 23:48   #6
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Glad to know that it is found to be informative by you.
@BBScad:
As ruffyrider & Ansuman has noted, in basic terms, The 4H gear ratio splits the engine power equally among front & rear axle of a 4WD Vehicle in 50:50 manner. i.e. 1:1 Ratio.
In 4L mode, the engine power is delivered to both the axles equally but here more torque is generated as the ratio is split as 2.78:1 in case of Mahindra Jeeps & in Wrangler Rubicon Jeep its 4.10:1 (Best for climbing steep inclines & rock-crawling stuff).

To simplify this technical terms you can visualize the scenario in which one gear is rotating the other gear of equal radius:4H & consider one gear of large radius is rotating other gear having shorter radius: 4L. Here ratio 4:1 means for every 1 rotation of larger gear, the shorter one will rotate 4 times (thus multiplying the torque)
Hope its not that bad
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Old 23rd September 2008, 01:11   #7
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Quote:
Originally Posted by offroad_maniac View Post

To simplify this technical terms you can visualize the scenario in which one gear is rotating the other gear of equal radius:4H & consider one gear of large radius is rotating other gear having shorter radius: 4L. Here ratio 4:1 means for every 1 rotation of larger gear, the shorter one will rotate 4 times (thus multiplying the torque)
Hope its not that bad
NOT bad at all. i totally get it. thanks again.
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Old 23rd September 2008, 08:54   #8
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Quote:
Originally Posted by offroad_maniac View Post
The 4H gear ratio splits the engine power equally among front & rear axle of a 4WD Vehicle in 50:50 manner. i.e. 1:1 Ratio.
Not in every case,For example Pajero has 2 4h options with and without power split.
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Old 23rd September 2008, 08:57   #9
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Quote:
Originally Posted by offroad_maniac View Post
As ruffyrider & Ansuman has noted, in basic terms, The 4H gear ratio splits the engine power equally among front & rear axle of a 4WD Vehicle in 50:50 manner. i.e. 1:1 Ratio.
In case of GV it is 53:47 split for rear/front.
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Old 23rd September 2008, 12:05   #10
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@ O_M excellent article. Really informative.
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Old 23rd September 2008, 13:55   #11
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Quote:
Originally Posted by RuffRyder View Post
2H = 2wheel high gearing. Normal rear-wheel drive. Use this with normal driving on tarred roads and dry sand roads. Never drive faster than 100 km/h.
Why should one not drive faster than 100 kph in 2H?
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Old 23rd September 2008, 14:31   #12
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Quote:
Originally Posted by hrag View Post
Why should one not drive faster than 100 kph in 2H?
Yeah, I too wondered about that. May be he means in 4H in the absence of center diff with LSD.
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Old 23rd September 2008, 17:30   #13
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Originally Posted by hrag View Post
Why should one not drive faster than 100 kph in 2H?
its not that you cannot drive more than 100km/h but it is advised that we should not as it can have adverse effects on the gearbox and the 4x4 cannot maitain ratios of that speed and also it does not make sense to use 4x4 on nice straight even roads..
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Old 23rd September 2008, 18:13   #14
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Swami, you said never drive faster than 100 kph in 2H. In 2H, one can pretty much do anything one wants On The Road. Nothing adverse will happen to the gearbox above 100 kph in 2H.

I guess you intended to put that line under the 4H section and what you originally typed was by mistake.
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Old 23rd September 2008, 18:38   #15
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Quote:
Originally Posted by RuffRyder View Post
its not that you cannot drive more than 100km/h but it is advised that we should not as it can have adverse effects on the gearbox and the 4x4 cannot maitain ratios of that speed and also it does not make sense to use 4x4 on nice straight even roads..
Why should 4x4 system maintain ratios in 2H? It is not even engaged. I thought you mentioned 2H by mistake, but you are not correcting it.
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