4X4 System?
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From: Needville Texas
This is how an electronic shift on the fly transfer case works, I hope this clears up some confusion.
The transfer case is equipped with an electromagnetic clutch which is located inside the case. This clutch is used to spin up the front driveline when shifting from 2WD to 4H mode at speed. When the control switch on the instrument panel is turned, the generic electronic module (GEM) recognizes that a shift has been requested and activates the electromagnetic clutch and the relays which power the transfer case shift motor. When the shift motor reaches the desired position, as determined by the contact plate position inputs to the GEM, power to the shift relays and motors will be removed. When the transfer case front and rear output shafts are synchronized, the spring loaded lockup collar mechanically engages the mainshaft hub to the drive sprocket. Finally, the front axle collar is engaged and the electromagnetic clutch is deactivated.
The electromagnetic clutch works the same way has your a/c compressor clutch does.
The transfer case is equipped with an electromagnetic clutch which is located inside the case. This clutch is used to spin up the front driveline when shifting from 2WD to 4H mode at speed. When the control switch on the instrument panel is turned, the generic electronic module (GEM) recognizes that a shift has been requested and activates the electromagnetic clutch and the relays which power the transfer case shift motor. When the shift motor reaches the desired position, as determined by the contact plate position inputs to the GEM, power to the shift relays and motors will be removed. When the transfer case front and rear output shafts are synchronized, the spring loaded lockup collar mechanically engages the mainshaft hub to the drive sprocket. Finally, the front axle collar is engaged and the electromagnetic clutch is deactivated.
The electromagnetic clutch works the same way has your a/c compressor clutch does.
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From: northeast tenn
well now that i am totaly confused......."just a lil bit" umm i was thinkin while reading the replies.....i have come to one conclusion.........."who/ me cares what takes place with the ****/stick" as long as the transfer case engages......and gives us/me 4 wheel drive...........thinkin back my Nissan hardbody had like a 1 inch throw to engage the 4 hi set-up.......i never gave the less than 1/2 inch engagement on my "F" any though......ahh well.thanx for the insight from all.......
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From: Windsor,Ontario,Canada
Ok Simple test if you have a Manual SOTF.
With 4Hi engaged the front drive shaft will not turn if you are in Gear (manual tranny) or park (automatic). Try it. In 2Hi the front shaft will turn.
If the shift lever simply completed an electrical connection when you shift into 4Hi and the Electromagnetical clutch completed the shift, then with the Shift Lever is pulled into 4Hi the drive shaft should not turn as per the above test. Disconnect the battery and Shift into 4Hi. If the Electromagnetic clutch has no power then it will not complete the shift and the front drive shaft should turn. I tried this and the drive shaft did not turn proving that the lever shifts the fork and not the electromagnetical clutch. BTW the electric shift works in a similar way but with an electric shift motor moving the shift forks.
Regards
Jean Marc Chartier
With 4Hi engaged the front drive shaft will not turn if you are in Gear (manual tranny) or park (automatic). Try it. In 2Hi the front shaft will turn.
If the shift lever simply completed an electrical connection when you shift into 4Hi and the Electromagnetical clutch completed the shift, then with the Shift Lever is pulled into 4Hi the drive shaft should not turn as per the above test. Disconnect the battery and Shift into 4Hi. If the Electromagnetic clutch has no power then it will not complete the shift and the front drive shaft should turn. I tried this and the drive shaft did not turn proving that the lever shifts the fork and not the electromagnetical clutch. BTW the electric shift works in a similar way but with an electric shift motor moving the shift forks.
Regards
Jean Marc Chartier
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From: Needville Texas
Jean, you are correct in saying the electromagnetic clutch doesn't make the shift, it gets the front shaft started spinning so that the shift fork can smoothly engage the front shaft. The electromagnetic clutch has no effect on the shift when sitting still, with out the electromagnetic clutch your transfer case would grind if you shifted on the fly without the hubs already locked. In real terms the electromagnetic clutch syncronyzes the front and rear driveshaft
The differance between ESOTF nad MSOTF is ESOTF has a **** on the dash and MSOTF has a lever on the floor. They both work exactly the same the only differance is the operator input.
The differance between ESOTF nad MSOTF is ESOTF has a **** on the dash and MSOTF has a lever on the floor. They both work exactly the same the only differance is the operator input.
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Joined: Dec 1997
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From: Windsor,Ontario,Canada
Can anyone answer this? Why is there a Neutral position in the Manual T-case? I like having it, but have never really needed it. Is it for flat towing? My truck is over 5200 lbs, I would need a tank to tow it.
Regards
Jean Marc Chartier
Regards
Jean Marc Chartier
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From: DeLand, FL
JMC
I'm not trying to be deliberately obtuse (ever see the Shawshank Redemption?), but a question just occured to me.
Remember that I posited that the 4-hi gear was always engaged even in 2x4. My reasoning behind this was that 4-hi is in essence a direct drive, and therefore the truck would easily operate with this engaged in 2x4, and the final step would simply to spin up the front shaft, connect the right axle, and lock the chain sprocket. But then I was convinced otherwise from the info here.
Now my question is this (re/your neutral comment), if 4-Hi gear is not ALWAYS engaged, then how does 4x4 neutral DISENGAGE and override everything, even 2x4 tranny? Do you understand my question? Going to 4x4 neutral must take it out of whatever is 4x4 hi, as well as what is 2x4....That makes me think that, indeed, the 4x4 hi gear is a direct drive gear that is always engaged. Where am I going wrong? There seems to be no other scenario that makes this work.
I'm not trying to be deliberately obtuse (ever see the Shawshank Redemption?), but a question just occured to me.
Remember that I posited that the 4-hi gear was always engaged even in 2x4. My reasoning behind this was that 4-hi is in essence a direct drive, and therefore the truck would easily operate with this engaged in 2x4, and the final step would simply to spin up the front shaft, connect the right axle, and lock the chain sprocket. But then I was convinced otherwise from the info here.
Now my question is this (re/your neutral comment), if 4-Hi gear is not ALWAYS engaged, then how does 4x4 neutral DISENGAGE and override everything, even 2x4 tranny? Do you understand my question? Going to 4x4 neutral must take it out of whatever is 4x4 hi, as well as what is 2x4....That makes me think that, indeed, the 4x4 hi gear is a direct drive gear that is always engaged. Where am I going wrong? There seems to be no other scenario that makes this work.
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JMC, I think the Neutral position in the transfer case is a throwback to the days when trucks had Power Take Offs (PTOs). The only advantage to having it these days is the ability to tow the truck on all 4 wheels while in Neutral. Other than that, I don't know why else it's there.
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From: Along Lake Erie
From the 2001 Ford Service manual (minus the pictures.... the graphics wouldn't copy... sorry)
Transfer Case — Power Flow
In the neutral position, no power is transmitted to the front or rear drivetrain.
Power Flow in 2H
When the driver selects 2H, the (A) reduction hub is in the forward position and puts the transfer case into direct drive. The (B) input shaft and (C) rear output shaft are locked together. The (D) 4-wheel drive lockup hub is in the forward position disengaging the front driveline.
Power Flow in 4H
In 4-wheel drive — high range (4H), the (A) 4-wheel drive lockup hub moves rearward and locks the (B) chain sprocket and (C) chain to the (D) rear output shaft. Both the (D) rear output shaft and (E) front output shaft are being driven in high range. The (F) reduction hub is in the forward position.
Power Flow in 4L
In 4-wheel drive — low range (4L), the (A) reduction hub moves rearward and the (B) low range gearset is engaged to the (C) rear output shaft. The ring gear is locked and results in the (B) front planet gear turning slower than the (D) input shaft. This in turn makes the (C) rear output shaft and (E) front output shaft turn at a slower speed than the (D) input shaft. This action increases the pulling power available to the wheels.
Don't know if that clears up anything.... I'll try and remember to bring the printouts to the dunes... maybe someone can scan them and post a link... my scanner's down at the moment...
-Joe-
Transfer Case — Power Flow
In the neutral position, no power is transmitted to the front or rear drivetrain.
Power Flow in 2H
When the driver selects 2H, the (A) reduction hub is in the forward position and puts the transfer case into direct drive. The (B) input shaft and (C) rear output shaft are locked together. The (D) 4-wheel drive lockup hub is in the forward position disengaging the front driveline.
Power Flow in 4H
In 4-wheel drive — high range (4H), the (A) 4-wheel drive lockup hub moves rearward and locks the (B) chain sprocket and (C) chain to the (D) rear output shaft. Both the (D) rear output shaft and (E) front output shaft are being driven in high range. The (F) reduction hub is in the forward position.
Power Flow in 4L
In 4-wheel drive — low range (4L), the (A) reduction hub moves rearward and the (B) low range gearset is engaged to the (C) rear output shaft. The ring gear is locked and results in the (B) front planet gear turning slower than the (D) input shaft. This in turn makes the (C) rear output shaft and (E) front output shaft turn at a slower speed than the (D) input shaft. This action increases the pulling power available to the wheels.
Don't know if that clears up anything.... I'll try and remember to bring the printouts to the dunes... maybe someone can scan them and post a link... my scanner's down at the moment...
-Joe-
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Joined: Jan 2000
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From: Along Lake Erie
two more bits of info.... I think these might be more useful...
Transfer Case — Mechanical Shift On The Fly (MSOF) Operation
The mechanical shift on the fly (MSOF) system is a manual shift 4WD system that allows the operator to chose between two different 4x4 modes as well as 2-wheel drive. The operator can switch between 2WD and 4H mode at speeds up to 88 km/h (55 mph). To engage or disengage 4L range, the vehicle speed must be less than 5 km/h (3 mph), the brake pedal depressed, and the transmission must be in NEUTRAL.
Shifts between 2H and 4H can be made at a stop or any forward speed up to 88 km/h (55 mph). At temperatures below 0ºC (32ºF) shifts should not be performed above 72 km/h (45 mph).
The transfer case is equipped with an electromagnetic cluch which is located inside the case. This clutch is used to spin up the front driveline when shifting from 2WD to 4x4 mode at speed. When the manual shift lever is moved, this activates the 4WD indicator switch, 4WD electric clutch relay, and the electromagnetic clutch. When the transfer case front and rear output shafts are synchronized, the spring loaded lockup collar mechanically engages the mainshaft hub to the drive sprocket. Finally, the front axle collar is engaged and the electromagnetic clutch is deactivated.
Transfer Case — Electronic Shift on the Fly (ESOF) Operation
The electronic shift on the fly (ESOF) system is an electronic shift 4x4 system that allows the operator to choose between two different 4x4 modes as well as 2-wheel drive. The operator can switch between 2WD and 4H mode at speeds up to 88 km/h (55 mph). To engage or disengage 4L range, the vehicle speed must be less than 5 km/h (3 mph), the brake pedal depressed, and the transmission must be in NEUTRAL.
The transfer case is equipped with an electromagnetic clutch which is located inside the case. This clutch is used to spin up the front driveline when shifting from 2WD to 4H mode at speed. When the control switch on the instrument panel is turned, the generic electronic module (GEM) recognizes that a shift has been requested and activates the electromagnetic clutch and the relays which power the transfer case shift motor. When the shift motor reaches the desired position, as determined by the contact plate position inputs to the GEM, power to the shift relays and motors will be removed. When the transfer case front and rear output shafts are synchronized, the spring loaded lockup collar mechanically engages the mainshaft hub to the drive sprocket. Finally, the front axle collar is engaged and the electromagnetic clutch is deactivated.
Shifts between 2WD and 4H can be made at any speed up to 88 km/h (55 mph). Listed below are the inputs and outputs needed by the GEM to execute a change between any of these modes.
Feature Inputs:
l 4WD mode switch (various resistances; go to Table 1).
l Contact plate position inputs A, B, C, D (grounded when closed, open circuit when open; go to Table 4).
Feature Outputs:
l 4x4 shift motor relay outputs (go to Table 2).
l Transfer case clutch relay (grounded when relay is activated, open circuit when relay is deactivated).
l 4x2/4x4 vacuum solenoid (grounded when activated, open circuit when deactivated).
l Cluster indicators (ground when activated, open circuit when deactivated).
When shifting into or out of 4L, the GEM requires that the vehicle speed be less than 5 km/h (3 mph), the brake is applied, and the transmission is in NEUTRAL.
Feature Inputs:
l 4WD Mode Switch (various resistances; go to Table 1).
l Contact Plate Position Inputs A, B, C, D (grounded when closed, open circuit when open; go to Table 4).
l Output Speed Shaft (OSS) Sensor (Sinusoid Signal: 0.7V-20V, 2.2 Hz/mph).
l Brake Input (battery voltage when brake is depressed, open circuit when not activated).
l Transmission Range Sensor (grounded when transmission is in NEUTRAL, open circuit otherwise).
l Start/Clutch Depressed Input (go to Table 3).
Feature Outputs:
l 4x4 Shift Motor Relay Outputs (go to Table 2).
l 4x2/4x4 Vacuum Solenoid (grounded when activated, open circuit when deactivated).
l Cluster Indicators (grounded when activated, open circuit when deactivated).
Transfer Case — Mechanical Shift On The Fly (MSOF) Operation
The mechanical shift on the fly (MSOF) system is a manual shift 4WD system that allows the operator to chose between two different 4x4 modes as well as 2-wheel drive. The operator can switch between 2WD and 4H mode at speeds up to 88 km/h (55 mph). To engage or disengage 4L range, the vehicle speed must be less than 5 km/h (3 mph), the brake pedal depressed, and the transmission must be in NEUTRAL.
Shifts between 2H and 4H can be made at a stop or any forward speed up to 88 km/h (55 mph). At temperatures below 0ºC (32ºF) shifts should not be performed above 72 km/h (45 mph).
The transfer case is equipped with an electromagnetic cluch which is located inside the case. This clutch is used to spin up the front driveline when shifting from 2WD to 4x4 mode at speed. When the manual shift lever is moved, this activates the 4WD indicator switch, 4WD electric clutch relay, and the electromagnetic clutch. When the transfer case front and rear output shafts are synchronized, the spring loaded lockup collar mechanically engages the mainshaft hub to the drive sprocket. Finally, the front axle collar is engaged and the electromagnetic clutch is deactivated.
Transfer Case — Electronic Shift on the Fly (ESOF) Operation
The electronic shift on the fly (ESOF) system is an electronic shift 4x4 system that allows the operator to choose between two different 4x4 modes as well as 2-wheel drive. The operator can switch between 2WD and 4H mode at speeds up to 88 km/h (55 mph). To engage or disengage 4L range, the vehicle speed must be less than 5 km/h (3 mph), the brake pedal depressed, and the transmission must be in NEUTRAL.
The transfer case is equipped with an electromagnetic clutch which is located inside the case. This clutch is used to spin up the front driveline when shifting from 2WD to 4H mode at speed. When the control switch on the instrument panel is turned, the generic electronic module (GEM) recognizes that a shift has been requested and activates the electromagnetic clutch and the relays which power the transfer case shift motor. When the shift motor reaches the desired position, as determined by the contact plate position inputs to the GEM, power to the shift relays and motors will be removed. When the transfer case front and rear output shafts are synchronized, the spring loaded lockup collar mechanically engages the mainshaft hub to the drive sprocket. Finally, the front axle collar is engaged and the electromagnetic clutch is deactivated.
Shifts between 2WD and 4H can be made at any speed up to 88 km/h (55 mph). Listed below are the inputs and outputs needed by the GEM to execute a change between any of these modes.
Feature Inputs:
l 4WD mode switch (various resistances; go to Table 1).
l Contact plate position inputs A, B, C, D (grounded when closed, open circuit when open; go to Table 4).
Feature Outputs:
l 4x4 shift motor relay outputs (go to Table 2).
l Transfer case clutch relay (grounded when relay is activated, open circuit when relay is deactivated).
l 4x2/4x4 vacuum solenoid (grounded when activated, open circuit when deactivated).
l Cluster indicators (ground when activated, open circuit when deactivated).
When shifting into or out of 4L, the GEM requires that the vehicle speed be less than 5 km/h (3 mph), the brake is applied, and the transmission is in NEUTRAL.
Feature Inputs:
l 4WD Mode Switch (various resistances; go to Table 1).
l Contact Plate Position Inputs A, B, C, D (grounded when closed, open circuit when open; go to Table 4).
l Output Speed Shaft (OSS) Sensor (Sinusoid Signal: 0.7V-20V, 2.2 Hz/mph).
l Brake Input (battery voltage when brake is depressed, open circuit when not activated).
l Transmission Range Sensor (grounded when transmission is in NEUTRAL, open circuit otherwise).
l Start/Clutch Depressed Input (go to Table 3).
Feature Outputs:
l 4x4 Shift Motor Relay Outputs (go to Table 2).
l 4x2/4x4 Vacuum Solenoid (grounded when activated, open circuit when deactivated).
l Cluster Indicators (grounded when activated, open circuit when deactivated).
Last edited by GIJoeCam; Aug 12, 2002 at 07:40 PM.
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From: DeLand, FL
GIJoeCam
No, that's okay I don't need a scan, thanks for the info. It sounds like what I was saying is correct, in essence 4x4 Hi is engaged all the time (except that the chain sprocket isn't locked and the front driveshaft and right side axle isn't turning). But when you hit that 4-Hi lever from 4x2 or 2x4 or whatever, the synch or clutch hub or whatever in the transfer case doesn't "go" into the 4-Hi gear, because it's already in that gear because it is a direct drive gear. When you go to 4-Low, you take it out of the direct drive gear (which is engaged in either 4x2 or 4x4 Hi) and into the 4-lo gear ration.
It is just like a manual tranny, which is always in 4th gear so to speak.
No, that's okay I don't need a scan, thanks for the info. It sounds like what I was saying is correct, in essence 4x4 Hi is engaged all the time (except that the chain sprocket isn't locked and the front driveshaft and right side axle isn't turning). But when you hit that 4-Hi lever from 4x2 or 2x4 or whatever, the synch or clutch hub or whatever in the transfer case doesn't "go" into the 4-Hi gear, because it's already in that gear because it is a direct drive gear. When you go to 4-Low, you take it out of the direct drive gear (which is engaged in either 4x2 or 4x4 Hi) and into the 4-lo gear ration.
It is just like a manual tranny, which is always in 4th gear so to speak.
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Joined: Jan 2000
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From: Along Lake Erie
Originally posted by cpadpl
GIJoeCam
It sounds like what I was saying is correct, in essence 4x4 Hi is engaged all the time (except that the chain sprocket isn't locked and the front driveshaft and right side axle isn't turning).
GIJoeCam
It sounds like what I was saying is correct, in essence 4x4 Hi is engaged all the time (except that the chain sprocket isn't locked and the front driveshaft and right side axle isn't turning).
I think I understand what you are saying... basically, when you engage 4hi from 2wd, the transfer case piggy-backs the front half of the drivetrain onto the rear half. Is that what you're saying in a nut-shell?
Does anyone remember the original question?
JMC,
as for why the manual t-case has neutral, you are correct... it's ideally for towing. You can flat tow a manual transmission vehicle for any distance you want without hurting the transmission because the gears and bearings are splash-lubricated (even in neutral). Unfortunately, since the auto trans relies on positive pump pressure to thoroughly lubricate the bearings, towing speeds and distance are severely limited. (Note: The following does not necessarily apply in your case because you have both a manual trans and a manual t-case). If you wanted to tow an auto trans 4x4 vehicle, the easiest way to do so would be to de-couple the rear driveshaft from the trans output. A manual t-case makes that a snap.
Incidentally, On the explorers, there is a dealer-installed option available to equip the electronic sotf 4wd with a neutral position... basically a couple of relays, a new switch, and some possible re-programming of the GEM.... all it does is stop the t-case in the neutral position between 4 hi and 4 low.
No, as for why you'd need it? Obviously, towing, for one. possibly (and this is a stretch) in a winching situation where your truck was buried, not running (or the fan was underwater and you wouldn't want it running) and you needed neutral to allow the truck to roll out of its hole, or what about when being loaded onto a flat-bed if it left you stranded? (I know, with a manual trans it's not a problem, but what about an auto?) Just pop it in neutral instead of dealing with the stupid shifter... ummm, can't think of anything too practical, but I'm still thinking I remember reading something a long time ago about its usefulness when winching... can't remember off-hand...
-Joe-
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Joined: Dec 1997
Posts: 9,417
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From: Windsor,Ontario,Canada
Ok Here goes. Th T-case has in input shaft and an out put shaft. These shafts are comprised of the output shaft and the Front Planrt Gear Set. The splines on the Front Planet mesh with the Tranny Output Shaft . So the Front Planet always turns when the Tranny Output Shaft turns. On the ESOTF cases there are 2 speed positions Hi and Lo. Both these positions lock the Front Planet to the Output Shaft so the putput shaft on this model is always turning with the output shaft of the tranny. It is either turinig at the same speed ot slower, but always turning. That is why you can not flat tow an ESOTF T-Case truck. The rear wheels turn the drive shaft, the drive shaft turns the T-case Output Shaft the... all the wat to the tranny output shaft. It this shaft turns and the tranny pump is not operational there is no lube to the bearings in the rear of the tranny. On the MSOTF T-case there is a third speed, NEUTRAL. This disengages the T-case Front Planet from the T-case Output Shaft.
So cpadpl for the ESOTF you are correct in essenct the Input Shaft and Output Shaft turn as one. But not so on the MSOTF. You are awarded ½ star for being partially correct and ½ star for sticking to it.
Sorry could not resist. My EVIL TWIN put me up to it.
Regards
Jean Marc Chartier
So cpadpl for the ESOTF you are correct in essenct the Input Shaft and Output Shaft turn as one. But not so on the MSOTF. You are awarded ½ star for being partially correct and ½ star for sticking to it.
Sorry could not resist. My EVIL TWIN put me up to it.Regards
Jean Marc Chartier
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Posts: 450
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From: DeLand, FL
GIJoeCam
Yes, that's exactly what I'm saying. There's no special 4x4 Hi gear that a synch goes into when 4x4 is engaged (meaning it's already engaged). There is such a gear for 4xLo. For one, I couldn't figure out why engaging 4x4 Hi was in essence just a 1/2 inch tap to the shifter, but going into 4x4 Lo it's a a$$-haul around the block. Then when JMC mentioned T-case neutral, I couldn't figure out how that put the whole truck in neutral. With the floor shifter, pulling that shifter from 4x4 Hi to Neutral means you are disconnect something that renders both 4x4 and 4x2 neutral, which tells me that 4x4 Hi and 4x2 are using the same driving gear in the T-case (i.e. direct drive...)
Does that makes sense?
Yes, that's exactly what I'm saying. There's no special 4x4 Hi gear that a synch goes into when 4x4 is engaged (meaning it's already engaged). There is such a gear for 4xLo. For one, I couldn't figure out why engaging 4x4 Hi was in essence just a 1/2 inch tap to the shifter, but going into 4x4 Lo it's a a$$-haul around the block. Then when JMC mentioned T-case neutral, I couldn't figure out how that put the whole truck in neutral. With the floor shifter, pulling that shifter from 4x4 Hi to Neutral means you are disconnect something that renders both 4x4 and 4x2 neutral, which tells me that 4x4 Hi and 4x2 are using the same driving gear in the T-case (i.e. direct drive...)
Does that makes sense?
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Joined: Jun 2001
Posts: 450
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From: DeLand, FL
JMC
Now I'm thoroughly confused....My eyes glazed over with all the acronyms you are using....
I think I'm pulling out of the contest due to being severely outmatched. I was under the impression our T-case was the typical driveshaft-layshaft deal. The T-case's I've seen have a high range input gear which is the driving gear, always engaged by the sliding clutch unless you yank it out (neutral). The HRI gear turns the counter gear, which turns the LRI driving gear, which turns the LRI driven gear. The HRI driving gear and LRI driven gear are right next to each other, like this first line is input shaft and second is layshaft, bottom is front driveshaft (ing means driving, en means driven):
--- HRI-ing[clutch]....LRI-en -- drive sprocket
--- HRI-en................LRI-ing |
front driveshaft------- driven sprocket
Just like 4th gear on manual trannies, the HRI Driving is splined to the input shaft. It always turns and always turns HRI Driven and thus LRI Driving always spins. The LRI Driven is not splined to the output shaft (and just spins). The clutch is splined to the output shaft. In this system, in order to be able to drive in 4x2, the HRI driving must be engaged by the clutch in order to lock input shaft to output shaft. Therefore, the system is ready for 4x4 Hi use, only thing that needs to be done is chain sprocket needs to be locked and front driveshaft/right axle gear engaged.
Furthermore, under this system, the organization of the floor shifting sequence makes sense. Could you imagine if you could knock the whole truck into neutral just by pulling the 4x4 level too far down? My theory was that (See above) clutch was always engaged in HRI driving in 4x2. When you pulled down into 4x4 Hi, the only thing that happened was electronic solenoid BS and sprocket locking. When you slap the shifter over to the left you are now engaging the fork that will pull your clutch in a straight shot from HRI driving, to neutral, and then to LRI driven.
But like I said, that was just my theory...I had no idea about planetary gearsets in the T-case...just goes to show you I'm an idiot.....
Now I'm thoroughly confused....My eyes glazed over with all the acronyms you are using....
I think I'm pulling out of the contest due to being severely outmatched. I was under the impression our T-case was the typical driveshaft-layshaft deal. The T-case's I've seen have a high range input gear which is the driving gear, always engaged by the sliding clutch unless you yank it out (neutral). The HRI gear turns the counter gear, which turns the LRI driving gear, which turns the LRI driven gear. The HRI driving gear and LRI driven gear are right next to each other, like this first line is input shaft and second is layshaft, bottom is front driveshaft (ing means driving, en means driven):
--- HRI-ing[clutch]....LRI-en -- drive sprocket
--- HRI-en................LRI-ing |
front driveshaft------- driven sprocket
Just like 4th gear on manual trannies, the HRI Driving is splined to the input shaft. It always turns and always turns HRI Driven and thus LRI Driving always spins. The LRI Driven is not splined to the output shaft (and just spins). The clutch is splined to the output shaft. In this system, in order to be able to drive in 4x2, the HRI driving must be engaged by the clutch in order to lock input shaft to output shaft. Therefore, the system is ready for 4x4 Hi use, only thing that needs to be done is chain sprocket needs to be locked and front driveshaft/right axle gear engaged.
Furthermore, under this system, the organization of the floor shifting sequence makes sense. Could you imagine if you could knock the whole truck into neutral just by pulling the 4x4 level too far down? My theory was that (See above) clutch was always engaged in HRI driving in 4x2. When you pulled down into 4x4 Hi, the only thing that happened was electronic solenoid BS and sprocket locking. When you slap the shifter over to the left you are now engaging the fork that will pull your clutch in a straight shot from HRI driving, to neutral, and then to LRI driven.
But like I said, that was just my theory...I had no idea about planetary gearsets in the T-case...just goes to show you I'm an idiot.....
Last edited by cpadpl; Aug 13, 2002 at 09:42 PM.
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From: DeLand, FL
Originally posted by GIJoeCam
From the 2001 Ford Service manual (minus the pictures.... the graphics wouldn't copy... sorry)
Power Flow in 2H
When the driver selects 2H, the (A) reduction hub is in the forward position and puts the transfer case into direct drive. The (B) input shaft and (C) rear output shaft are locked together. The (D) 4-wheel drive lockup hub is in the forward position disengaging the front driveline.
Power Flow in 4H
In 4-wheel drive — high range (4H), the (A) 4-wheel drive lockup hub moves rearward and locks the (B) chain sprocket and (C) chain to the (D) rear output shaft. Both the (D) rear output shaft and (E) front output shaft are being driven in high range. The (F) reduction hub is in the forward position.
-Joe-
From the 2001 Ford Service manual (minus the pictures.... the graphics wouldn't copy... sorry)
Power Flow in 2H
When the driver selects 2H, the (A) reduction hub is in the forward position and puts the transfer case into direct drive. The (B) input shaft and (C) rear output shaft are locked together. The (D) 4-wheel drive lockup hub is in the forward position disengaging the front driveline.
Power Flow in 4H
In 4-wheel drive — high range (4H), the (A) 4-wheel drive lockup hub moves rearward and locks the (B) chain sprocket and (C) chain to the (D) rear output shaft. Both the (D) rear output shaft and (E) front output shaft are being driven in high range. The (F) reduction hub is in the forward position.
-Joe-
"In 4-wheel drive -- high range....the reduction hub is in the forward position..."
Isn't that what I'm saying? What they are calling the reduction hub locks the input and output shafts, and it doesn't change position when going from 4x2 to 4x4-Hi....They are in the forward position under both situations...