Team-BHP - Driving all four wheels: how is it done?

Quote:

Originally Posted by Sutripta (Post 3591160)

Just to establish context, we are talking of

aren't we? (Essentially Scorpio 4X4 manual vs auto)
I didn't know this, and would never have guessed!

Regards
Sutripta

PS.- I still don't get it. stupid: If someone could please explain ...

I think your PS sums it up nicely and I think further explanations, or corrections of my mis-statements on my part are futile in this case.

The torque converter of an automatic transmission allows much more slippage than the counterpart clutch of a manual transmission. You can, for example, be in DRIVE in an automatic, be on a steep hill facing up, and find yourself rolling backward down the slope at an alarming rate even though you are in DRIVE first gear. This slippage tends to lessen some of the effect of wind up since the post-tranny drivetrain stuff is not anchored by a manual clutch to the resistence of the fly wheel/engine to the same degree. You can still get windup damage however, if you try hard enough.

Okay, hang me.

What I am a little confused about reading the last few posts, that to absorb the difference in rotation between the front and rear drive shafts (to prevent the so called "wind up") this device known as Automatic transmission (and its associated Torque Converter) has to sit between these two shafts and not at a point preceding this junction, what am I missing here.

In otherwords, it would be wrong to assume that even if we deviced flexible shafts on a manual gearbox, upstream of the transfercase, that would prevent drivetrain binding (or "Wind up")

Quote:

Originally Posted by 4x4addict (Post 3591497)

DD Forget it man. If people take the time to read up on how a torque converter gear box works and how a part time 4x4 transfer case works, it will be clear.

Do I take that comment to mean that a part-time 4x4 vehicle equipped with torque converter-type automatic transmission, will not face driveline windup when driven in 4H or 4L mode on a road with curves and hairpins? Would you suggest any textbooks/articles/web links where this is explained explicitly?

Rahul, good to know. However, when we use engine braking in 1Low this wont help as lock up invariably cannot be used in 1st gear. the lock up in first gear has to get releases at some point otherwise it ceases to become an automatic.

SS-Traveller DD never said not but reduced. Looks like this argument is going regional now :-)

Let me take one last attempt at explaining. Scorpio 4x4 with auto transmission gets driven on winding tarred raids. Front diff is open, I.e. without lockers or LSD so both front axels can rotate at different speeds but no centre diff so front and rear axles cannot rotate at different rpms so the twist gets transferred to the gear box. From here you can do the research on how a old school torque converter auto tranny works.

Quote:

Originally Posted by 4x4addict (Post 3591561)

SS-Traveller DD never said not but reduced.

To what extent? Would be interested to know what can or can't be damaged with a torque converter auto 'box vis-a-vis a manual 'box, with the same (part-time 4wd) configuration. What happens to the transfer case? The driveshafts? The differential gears?

Quote:

Looks like this argument is going regional now :-)

Please explain. :confused: What region of where?

Quote:

Originally Posted by DirtyDan (Post 3591225)

Okay, hang me.

Walking out in the middle of a game! Not done, old boy!

Quote:

Originally Posted by 4x4addict (Post 3591561)

Let me take one last attempt at explaining. Scorpio 4x4 with auto transmission gets driven on winding tarred raids. Front diff is open, I.e. without lockers or LSD so both front axels can rotate at different speeds but no centre diff so front and rear axles cannot rotate at different rpms so the twist gets transferred to the gear box. .

Transfer case yes, gear box no.
And in the transfer case, only that part which would carry the torque from one axle to the other, not the part which transmits the torque from the main gearbox to the prop shafts.
In a normal Mahindra does releasing the clutch unwind/ lessen the windup?

Quote:

Originally Posted by SS-Traveller (Post 3591562)

Please explain. :confused: What region of where?

Thats simple. In the blue corner are ... and in the red corner are...
Oops. red has now become blue, and ...

Regards
Sutripta

Quote:

Originally Posted by Sutripta (Post 3591727)

Walking out in the middle of a game! Not done, old boy!

Do you frequently talk to people you think are not there, old boy?

Quote:

Originally Posted by Sutripta (Post 3591727)

In a normal Mahindra does releasing the clutch unwind/ lessen the windup?

In a normal Mahindra does DEPRESSING the clutch lessen the windup?

Quote:

Originally Posted by DirtyDan (Post 3591768)

Do you frequently talk to people you think are not there, old boy?

Shouting before it became a wilderness!

Quote:

In a normal Mahindra does DEPRESSING the clutch lessen the windup?

In a wannabe mechanics language, one engages and disengages/ releases a clutch.

And you are the person driving in the hills. You tell me!

Regards
Sutripta

Clutch pedal up (normal position) ---> Clutch engaged, connected to the fly wheel.
Clutch pedal down, depressed ---> clutch disengaged from the the fly wheel.

"Releasing" a clutch means foot allowing pedal to rise, engaging the clutch....'ay?

Sorry, I dont have much experience driving automatics, but, isnt the drivetrain wind up caused because the "transfer case" is locked, and not the gearbox?

The transfer case doesnt allow different speeds of front and rear prop shafts. and, when they try to do the same the drive train winds up?

Well, depressing the main gearbox clutch doesnt lessen the wind up. Releasing the front prop shaft drive does.