Poor mans locker, using the break.
Junior Member
Joined: Aug 2012
Posts: 61
Likes: 0
From: Golden, CO
Year: 1999
Model: Cherokee
Engine: 4.0
All this goes out the window with a traction adder. Using the brakes with a lsd definitely helps and a locker or spool will definitely provide torque to both wheels.
I don't want to argue about this anymore as it doesn't matter to me if we agree or not. I just don't want some poor sap stuck in the woods because he thought he could make his open diff a locker by pushing the brakes.
I don't want to argue about this anymore as it doesn't matter to me if we agree or not. I just don't want some poor sap stuck in the woods because he thought he could make his open diff a locker by pushing the brakes.
Senior Member
Joined: Nov 2011
Posts: 928
Likes: 0
From: Manhattan, Kansas
Year: 1997
Model: Cherokee
Engine: 4.0L
Regardless of loaf, open differentials are built to send power to the slipping wheel, so regardless of how much brake you send (unless you can stop only one wheel), you will still spin a tire on ice before you spin the one on rocks..
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 997
Likes: 1
From: Long Island NY
Year: 2000
Model: Cherokee
Post six violates the laws of physics, if that were true and you were to push on the gas more, the spinning tire could not spin any faster. However, because when you push on the gas the spinning wheel spins faster there must be a torque applied to it. You cannot have angular acceleration (tire spin) without torque. Anyone who has ever been stuck knows that if you push on the gas harder, the tire spins faster. Post 31 is straight up wrong. An open diff does not always split torque 50/50. A spool is the only way to always split torque 50/50 to each wheel. A performance differential maker I will trust on the subject, a brake manufacturer I will not. You were able to get unstuck because you applied less torque to the spinning wheel, not more. Static friction (what happens when a tire is rolling not spinning) is always greater than kinetic friction (what happens when a tire spins). By applying the brakes you use the friction force of the brakes to counteract some of the torque from the engine. This allows the tire to use the higher static frictional force to propel the vehicle forward.
This is from HowStuffWorks
"Differentials and Traction
The open differential always applies the same amount of torque to each wheel. There are two factors that determine how much torque can be applied to the wheels: equipment and traction. In dry conditions, when there is plenty of traction, the amount of torque applied to the wheels is limited by the engine and gearing; in a low traction situation, such as when driving on ice, the amount of torque is limited to the greatest amount that will not cause a wheel to slip under those conditions. So, even though a car may be able to produce more torque, there needs to be enough traction to transmit that torque to the ground. If you give the car more gas after the wheels start to slip, the wheels will just spin faster."
http://auto.howstuffworks.com/differential3.htm
Are they making this up too?
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 997
Likes: 1
From: Long Island NY
Year: 2000
Model: Cherokee
You are confused. The engine produces torque. The torque produced by the engine goes through the transmission and through the transfer case. 50% goes to the front, 50 to the rear. The amount of torque that the ground exerts back on the tire (to move the vehicle forward) has no affect on how much torque the engine produces
There is a whole lot of he said she said goin on in here against me. But nothing to support any claims. I dont mean to offend anyone in here, but I dont take what I read online as gospel. I like to see something that proves what I am reading.
On that note Im out for the night. Hope to continue with some thought provoking conversation in the morning.
CF Veteran
Joined: Aug 2011
Posts: 3,648
Likes: 4
Model: Cherokee
You still have angular acceleration to factor in.
So while one wheel is not moving Friction force is cancelling out your wheel speed while the friction on the other side plays almost no part. Your wheel speed goes up and so does your angular acceleration. Torque is rxf, f=ma, a is angular in this case, which appears to be what you have been leaving out. You hit the brakes, it evens the friction force opposing the force of forward motion.
Draw a fbd and don't forget all the forces.
So while one wheel is not moving Friction force is cancelling out your wheel speed while the friction on the other side plays almost no part. Your wheel speed goes up and so does your angular acceleration. Torque is rxf, f=ma, a is angular in this case, which appears to be what you have been leaving out. You hit the brakes, it evens the friction force opposing the force of forward motion.
Draw a fbd and don't forget all the forces.
Last edited by mr white; Mar 14, 2013 at 12:48 AM.
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 997
Likes: 1
From: Long Island NY
Year: 2000
Model: Cherokee
Im not forgetting Acceleration. But in order for the acceleration to increase the force needs to increase, a=f/m. If f doesnt change then the acceleation doesnt change. On a wheel in the air F- is small and doesnt need much F+ to acceleration. When you put the wheel on the ground the Friction, also known as traction combined with the weight of the vehicle increase the F- tremendously. F+ needs to increase even more to get a positive Force and and positive "a" acceleration to move the vehicle.
As someone pointed out before the engine cant produce zero Torque and it doesnt. Friction is a negative force, F-. The bearing and inertia of the axle assembly are negative. The force of the engine, F+, is the positive end. a=(F-+F)/m
As someone pointed out before the engine cant produce zero Torque and it doesnt. Friction is a negative force, F-. The bearing and inertia of the axle assembly are negative. The force of the engine, F+, is the positive end. a=(F-+F)/m
CF Veteran
Joined: Apr 2012
Posts: 1,659
Likes: 0
From: Dayton OH
Year: 1995
Model: Cherokee
Engine: 4.0
Okay, I have read this thread, an I have to say, that the op, (though he knows physics pretty well) has almost no idea how the whold 4x4 drivetrain works as a whole. **** the physics equations. Your torque will alwaysb the same front to rear
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 997
Likes: 1
From: Long Island NY
Year: 2000
Model: Cherokee
I NEVER said that. The transcase is a chain drive 50-50 spilt on power front to rear. What Im sayin is torque is ALWAYS spil 50-50 left to right in a open differential. The discussion is, if a wheel front and rear is spinning, is the engine producing torque, From what Ive read it is not. My physics equation is there to prove this saying that with out traction the engine makes very little torque. The stuck wheel is then not spinning because there isnt enough torque to over come the friction of the wheel on the ground.
Last edited by No4x4Yet; Mar 14, 2013 at 11:26 AM.
Junior Member
Joined: Aug 2012
Posts: 61
Likes: 0
From: Golden, CO
Year: 1999
Model: Cherokee
Engine: 4.0
Right, this guy has no idea what he is talking about and he is badly mistaken as to how an engine works. I could care less what he thinks. He like many engineers is good at piloting a desk, not much knowledge as to how things really work. Don't expect using the brakes to help much unless you have an lsd. Use common sense and be safe out there, I am unsubscribing from this thread.
CF Veteran
Joined: Apr 2012
Posts: 1,659
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From: Dayton OH
Year: 1995
Model: Cherokee
Engine: 4.0
I NEVER said that. The transcase is a chain drive 50-50 spilt on power front to rear. What Im sayin is torque is ALWAYS spil 50-50 left to right in a open differential. The discussion is, if a wheel front and rear is spinning, is the engine producing torque, From what Ive read it is not. My physics equation is there to prove this saying that with out traction the engine makes very little torque. The stuck wheel is then not spinning because there isnt enough torque to over come the friction of the wheel on the ground.
CF Veteran
Joined: Aug 2011
Posts: 3,648
Likes: 4
Model: Cherokee
Im not forgetting Acceleration. But in order for the acceleration to increase the force needs to increase, a=f/m. If f doesnt change then the acceleation doesnt change. On a wheel in the air F- is small and doesnt need much F+ to acceleration. When you put the wheel on the ground the Friction, also known as traction combined with the weight of the vehicle increase the F- tremendously. F+ needs to increase even more to get a positive Force and and positive "a" acceleration to move the vehicle.
As someone pointed out before the engine cant produce zero Torque and it doesnt. Friction is a negative force, F-. The bearing and inertia of the axle assembly are negative. The force of the engine, F+, is the positive end. a=(F-+F)/m
As someone pointed out before the engine cant produce zero Torque and it doesnt. Friction is a negative force, F-. The bearing and inertia of the axle assembly are negative. The force of the engine, F+, is the positive end. a=(F-+F)/m
Thread Starter
Senior Member
Joined: Jul 2010
Posts: 997
Likes: 1
From: Long Island NY
Year: 2000
Model: Cherokee
Horse poo, see I can yell out words to. I believe the term your looking for is Centripetal acceleration, which is related to Centrifugal FORCE. However that relates to the force from the center which would be the axle.
Im trying to have a intelligent conversation. I supported my claim with formulas and facts. I already disputed your acceleration claim. Unless you have something new and intelligent to add keep further comments to yourself. Maybe your should draw up a FBD?
Im trying to have a intelligent conversation. I supported my claim with formulas and facts. I already disputed your acceleration claim. Unless you have something new and intelligent to add keep further comments to yourself. Maybe your should draw up a FBD?
CF Veteran
Joined: Aug 2011
Posts: 3,648
Likes: 4
Model: Cherokee
Horse poo, see I can yell out words to. I believe the term your looking for is Centripetal acceleration, which is related to Centrifugal FORCE. However that relates to the force from the center which would be the axle.
Im trying to have a intelligent conversation. I supported my claim with formulas and facts. I already disputed your acceleration claim. Unless you have something new and intelligent to add keep further comments to yourself. Maybe your should draw up a FBD?
Im trying to have a intelligent conversation. I supported my claim with formulas and facts. I already disputed your acceleration claim. Unless you have something new and intelligent to add keep further comments to yourself. Maybe your should draw up a FBD?
http://en.wikipedia.org/wiki/Rotatio...d_a_fixed_axis
Senior Member
Joined: Oct 2011
Posts: 731
Likes: 0
From: St. Albert
Year: 1989
Model: Cherokee
Engine: 4.0L I6
I NEVER said that. The transcase is a chain drive 50-50 spilt on power front to rear. What Im sayin is torque is ALWAYS spil 50-50 left to right in a open differential. The discussion is, if a wheel front and rear is spinning, is the engine producing torque, From what Ive read it is not. My physics equation is there to prove this saying that with out traction the engine makes very little torque. The stuck wheel is then not spinning because there isnt enough torque to over come the friction of the wheel on the ground.
CF Veteran
Joined: Jun 2011
Posts: 2,720
Likes: 44
From: Gainesville GA
Year: 1999
Model: Cherokee (XJ)
Engine: 4.0
Here in lies your problem.
How There's smart & then there's book smart.
Stop reading & get out on a trail & you will figure out how & why stuff works.
This thread makes my head hurt.
Unsuscribed.
How There's smart & then there's book smart.
Stop reading & get out on a trail & you will figure out how & why stuff works.
This thread makes my head hurt.
Unsuscribed.
Last edited by Big David; Mar 14, 2013 at 03:51 PM.