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  29.März 2024 01:49:26

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 Thema: Emergency Braking C303/304/306  (Gelesen 4936 mal)
Anthony

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Emergency Braking C303/304/306
« am: 10.November 2007 12:7:46 »
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I have some concerns with how the braking system operates with the C303/304/306.  I have also asked this question else where.

With the C303/304/306 etc the brake system is complicated with the engagement of the front axle during heavy braking. I am not sure at what stage or how heavily one has to brake in order to bring this about. I understand that this is a safety function designed to prevent the rear wheels locking up before the fronts during heavy or emergency braking.

Other vehicles use a combination of supplying less braking force to the rear together with a Brake Proportioning Valve BPV which fine tunes the braking effort dependent on load. The Pinzgauer uses this system as does my LR 101 FC.

I am only interested in how this Volvo safety system functions on normal hard surfaced or public roads and highways not so much off the highway but on.

My concerns are that normal engagement of four wheel drive is not usualy an instantaneous affair. Also disengagement of four wheel drive is not normally instantaneous either especially on surfaced roads. That this might bring about unsatisfactory braking in an emergency where the rear brakes might lock up because the Volvo system does not engage quikly enough. The contrary is also a concern in which the Volvo safety system has engaged the front axle but might not release fast enough.

I can imagine a scenario where by my Volvo TGB 13 is being driven on wet narrow poorly cambered roads. I brake to avoid something and the rear wheels lock which might result in a skid. 

I am traveling on the same road having effected rapid retardation but the TGB still remains in 6x6 all wheel drive mode after I have released my brakes and does not does not revert to normal drive. I am rapidly approaching a series of tight bends. Will the TGB respond to the steering wheel? 

Normally if all wheels drive is operating steering can become difficult especially when negotiating tight bends as found on country roads here in Wales. The TGB with all axles engaged especially a 6x6 might be reluctant to turn into the corner resulting in a possible collision.

Are my fears unfounded? 

Do other members find the system operates safely at all times? 

Do others find that this system is faulted and might have brought about worrying moments? 

I would greatly appreciate some feedback and discussion about this.
I am wondering if at some stage that I might need to adapt a LPV to fit the TGB in order to have safe braking especially if I should fit disc brakes.

It is intended to use this vehicle frequently on and off road.

Grüße


Anthony
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Re:Emergency Braking C303/304/306
« am: 10.November 2007 12:25:57 »
Antwort mit Zitat nach oben
I have never tested it, but I can hear the vacuum-switch when braking hard.

I did not read everything while packing my suitcase for our travel to india - no more time. But the description of what is happening is misleading for my opinion:

"Enganging 4WD when braking hard"

does NOT mean: The car is driving forward now with all wheels!

Imagine: you brake and your right foot is on the LEFT pedal. Only idle power is comming from the engine.

In this case every engine can easyly be stalled from the brake. With full brakes you can not pull away, because every brake has to delete many times the power the engine has.

Result: The front and rear axles are connected, but the diffs are not locked.

Nothing surprising or dangerous should happen.

regards
michael
"oh, for sure, you can do it with a normal streetcar...."
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Re:Emergency Braking C303/304/306
« am: 10.November 2007 12:40:39 »
Antwort mit Zitat nach oben
Enjoy India! grin

Zitat:
"Engaging 4WD when braking hard"
does NOT mean: The car is driving forward now with all wheels!


I mean that the car would be in 4WD after hard braking that is front and rear wheel drive together , before it would have been in rear wheel drive only.

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Anthony
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Re:Emergency Braking C303/304/306
« am: 10.Dezember 2007 19:18:44 »
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all wheel driving is not connected to having problems driving corners. imagine what happens in a corner when...:

2WD(4WD in our case-c304) engaged:

- idleing engine (as michael describes) and slowing down (engine brake):

in extreme cases (ice or very slippery) the rear wheels may be sliding away as the front wheels are not (engine-)braked, when front wheels are spinning much faster as engine allows the rear axles. i don't think this can ever happen.
under normal conditions, when going off throttle, the car - which tend to understeer as the rear wheels want straight forward- will now be more steering then


- fully throttle engine and speeding up in a corner
under a slippy surface, car may brake out in the back (like a rear wheel driven BMW for example). on a dry surface one may experience tendence to understeering, you may have to steer more into the corner. especially with much weight and tight corners.
the back wheels want to go straight smiley

4WD(6WD for c304) engaged:

- ideling engine and slowing down (engine brake)

all wheels are equally slowed down, the behaviour is more balanced and there should be no braking out of front or rear.
surface does not matter but does the weigth balance (weigth shifting)

- fully throttle engine and speeding up

all wheels grip with the same force into the direction the front wheels give. the steering will continue very equally and neutral.
as the front wheels are driven, too, they will have more influence in the direction you steer than in 2wd(4wd) mode. the truck will do more what you want than in 2wd mode. (its a bit the front driven cars effect like 2wd audis- you throttle up the car and it goes more into corners)

i tested this with a new audi a6 3.0tdi quattro last week on wet surface in a corner to a autoroutes acceleration lane. absolutely no weight shifting due to appruptly braking or speeding up. only drift is neutral sideward. in this case you have to keep in mind the partly locking diffs and the visco diff of this street car, which the volvo doesn't have i think.
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Re:Emergency Braking C303/304/306
« am: 10.Dezember 2007 22:46:42 »
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Hi Chris,

Chris said, “all wheel driving is not connected to having problems driving corners. imagine what happens in a corner when...:

There is not a problem with having “all wheel drive on in corners.  There is a big problem in having permanent 4x4 or 6x6 when driving on the highway when it applies to a part time 4x4 or 6x6 transmission.  There is a difference, “all wheel drive relates to modern vehicles such as Landrover defender, Rangerover, Discovery, Post 94 G-Wagon, 80 series and later Landcruiser and others with an open central differential or a viscous differential.  Permanent 4x4 or 6x6 is the equivalent of driving those vehicles with the central dif locked or driving a series Landrover with part time 4x4 with the front axle engaged i.e. in 4x4

Only a few days ago I was leaving the off road track to my property when the centre differential of my 80 series Landcruiser refused to disengage before I entered the highway.  The effect of having the centre diff locked was to cause the car to crab uncontrollably and swerve side to side; it did not want to respond to the steering without using excessive force. After a short distance on the highway I had to repeatedly drive in reverse and swerve in order to disengage it.  This is a common scenario for people who might forget to disengage either 4x4 or the centre diff lock.  I might add that I use all my locks very frequently in order to make them operate smoothly and properly but occasionally this sort of thing still happens.  This is what I fear with the TGB but instead of it being known about it may come about just by applying the brakes to a certain pressure, who knows what, when I may least may want it and then fail to disengage quickly, reproducing the effects I reported above.



Chris said” 2WD(4WD in our case-c304) engaged:

- idleing engine (as michael describes) and slowing down (engine brake):

in extreme cases (ice or very slippery) the rear wheels may be sliding away as the front wheels are not (engine-)braked, when front wheels are spinning much faster as engine allows the rear axles. i don't think this can ever happen.
under normal conditions, when going off throttle, the car - which tend to understeer as the rear wheels want straight forward- will now be more steering then”

Yes, I can select 4x4 or 6x6 when I choose, when I decide that the conditions require it, not some antiquated 30 year old mechanical, unsympathetic system that may not be consistent or appropriate or what may applied when I least want it to be.  Not only that but I fear it will not release that quickly either.




Chris said- “fully throttle engine and speeding up in a corner
under a slippy surface, car may brake out in the back (like a rear wheel driven BMW for example). on a dry surface one may experience tendence to understeering, you may have to steer more into the corner. especially with much weight and tight corners.
the back wheels want to go straight  ”

Again I wil apply 6x6 when I want it, when I feel it appropriate, I do not want it just because I may have used the brakes recently.


Chris said “4WD(6WD for c304) engaged:

- ideling engine and slowing down (engine brake)

all wheels are equally slowed down, the behaviour is more balanced and there should be no braking out of front or rear.
surface does not matter but does the weigth balance (weigth shifting)

- fully throttle engine and speeding up

all wheels grip with the same force into the direction the front wheels give. the steering will continue very equally and neutral.
as the front wheels are driven, too, they will have more influence in the direction you steer than in 2wd(4wd) mode. the truck will do more what you want than in 2wd mode. (its a bit the front driven cars effect like 2wd audis- you throttle up the car and it goes more into corners)

As above I prefer to make the decisions and not relie an old mechanical system.

Chris said “i tested this with a new audi a6 3.0tdi quattro last week on wet surface in a corner to a autoroutes acceleration lane. absolutely no weight shifting due to appruptly braking or speeding up. only drift is neutral sideward. in this case you have to keep in mind the partly locking diffs and the visco diff of this street car, which the volvo doesn't have i think.”

Chris the Audi Quattro is a modern fly by wire machine; one can not use it to extol the virtues of “all wheel drive” in relation to a 30 year old part time 4x4 or 6x6.  The Audi Quattro has an electronically controlled viscous centre differential; it has all sorts of other computer controlled devices that control yaw, tilt swerve, skidding etc.  The Quattro is from another universe completely.  I only whish that these devices where employed in my TGB.

I am all for applying 4x4 or 6x6 when situations call for it and I choose.  I would eventually like my TGB to be all wheel drive using a modern gear box and transfer box that has a lockable central differential, preferably viscous as well like in the 80 Series Landcruiser or Rangerover for example.  All 6 wheels can then be driven permanently, safely, at all times.  This is completely different to driving a part time 4x4 or 6x6 in permanent 4x4 or 6x6 that is with all axles being driven without any differential between them. smiley

I apologise for not using the quotation system as provided by the web site but I have forgotten how to use it.
Grüße


Anthony
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Re:Emergency Braking C303/304/306
« am: 10.Dezember 2007 23:0:57 »
Antwort mit Zitat nach oben
hi anthony, of course noone wants to compare quattro techique with volvos 6wd.
but i cannot really see any problems in engaging or permanently driving 6x6 except for more friction and therefore more fuel consume...
dont mix up diff lock and 6x6, with diff lock on you are fucked up driving corners or even steer (as you said) but with 6wd its just front driven too. the force the wheels pull are exactly where you want them to (as you are in control of the steering) and the car will move whatever direction the front wheels point to. - at least if you throttle up.
proof me wrong if i am ?!


a small add: perhaps its possible to switch off the emergency all-wheel-drive if you want.
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« Letzte Änderung: 10.Dezember 2007 23:4:31 von Chris » Moderator benachrichtigen   Gespeichert
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Re:Emergency Braking C303/304/306
« am: 10.Dezember 2007 23:5:34 »
Antwort mit Zitat nach oben
Zitat von: Anthony am 10.Dezember 2007 22:46:42
I am all for applying 4x4 or 6x6 when situations call for it and I choose.  I would eventually like my TGB to be all wheel drive using a modern gear box and transfer box that has a lockable central differential, preferably viscous as well like in the 80 Series Landcruiser or Rangerover for example.  All 6 wheels can then be driven permanently, safely, at all times.  This is completely different to driving a part time 4x4 or 6x6 in permanent 4x4 or 6x6 that is with all axles being driven without any differential between them. smiley



I wouldn't jump at a 50/50 fulltime 4wd transfer box too quickly, at least not on a 6x6....you would need a 33/66 torque-ratio to become happy, and distribute torque evenly on all wheels, especially when going uphill, even more so if you put in a larger/stronger engine as well....add skidd-prone Goodyear/Trelleborg, and you might be looking at a rather unpredictable road behaviour in corners, acellerating or decellerating/engine-braking.
You don't want it to behave like a front-wheel-drive vehicle, do you?....;))
(only on very steep downhills it would level out, torque-ratio vs weight-distribution)

Note that a visco-LSD on top of a 50/50 center diff doesn't really change that behaviour, it only limits wheel spin when, after and as long as slip occurs....the initial breaking of traction it can not prevent, and that is what counts in corners.


Zitat:
I apologise for not using the quotation system as provided by the web site but I have forgotten how to use it.[/i]


It only works by inserting a sequence of {/quote} and {quote} after the alinea/sentence you want to quote{*}, and putting your answer inbetween (assuming there is more text to be quoted further below, hence the {quote} on the end (if you don't put it there right away, you will forget, and figuring it out later is much harder)

{*} use square brackets instead of accolades, of course (can't use them in text here, otherwise it becomes a format-command)



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Re:Emergency Braking C303/304/306
« am: 10.Dezember 2007 23:12:55 »
Antwort mit Zitat nach oben
My dear Chris,

The TGB 13 is part time 6x6 and putting it into full time 6x6 would be just the same as locking the central differential of a modern 4x4 such as in a Landrover.  In essence there is then no differential movement allowed it is exactly just the same, the axles would be locked together. As you so aptly put it one would be f--d going into corners.

I did on my way home to GB try the brakes hard and yes I could hear the vacuum activator hissing but I doubted very much that the front axle was ever engaged.  I suspect that it is slow to come in and therefore possibly sow to go off.

Zitat von: Chris am 10.Dezember 2007 23:0:57
hi anthony, of course noone wants to compare quattro techique with volvos 6wd.
but i cannot really see any problems in engaging or permanently driving 6x6 except for more friction and therefore more fuel consume...
dont mix up diff lock and 6x6, with diff lock on you are fucked up driving corners or even steer (as you said) but with 6wd its just front driven too. the force the wheels pull are exactly where you want them to (as you are in control of the steering) and the car will move whatever direction the front wheels point to. - at least if you throttle up.
proof me wrong if i am ?!
Grüße


Anthony
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Re:Emergency Braking C303/304/306
« am: 10.Dezember 2007 23:36:51 »
Antwort mit Zitat nach oben
Possibly you may be right I shall one day have to see.

Zitat:
I wouldn't jump at a 50/50 fulltime 4wd transfer box too quickly, at least not on a 6x6....you would need a 33/66 torque-ratio to become happy, and distribute torque evenly on all wheels,



Yes that is OK I am used to driving with both open and viscous differentials and I am aware what it is like and of its capabilities, I just prefer viscous as I feel that it is more sure footed on the road when being driven quikly and off road it is usualy sufficient for many situations, one only needs then to apply the diff lock as things become more serious and exciting. grin

Zitat:
Note that a visco-LSD on top of a 50/50 center diff doesn't really change that behaviour, it only limits wheel spin when, after and as long as slip occurs....the initial breaking of traction it can not prevent, and that is what counts in corners.



Thank you for reminding me about the quotations, Chris had given me a coaching session with it a few weeks ago but I am not using it often and so I am not very fluent with it, so I forget, its my age, well that is my excuse and I am sticking with it grin grin.

It works grin grin
Grüße


Anthony
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Re:Emergency Braking C303/304/306
« am: 10.Dezember 2007 23:49:12 »
Antwort mit Zitat nach oben
Zitat von: Anthony am 10.Dezember 2007 23:36:51
Possibly you may be right I shall one day have to see.

Zitat:
I wouldn't jump at a 50/50 fulltime 4wd transfer box too quickly, at least not on a 6x6....you would need a 33/66 torque-ratio to become happy, and distribute torque evenly on all wheels,



Yes that is OK I am used to driving with both open and viscous differentials and I am aware what it is like and of its capabilities, I just prefer viscous as I feel that it is more sure footed on the road when being driven quikly and off road it is usualy sufficient for many situations, one only needs then to apply the diff lock as things become more serious and exciting. grin



The Torsen unit in J12 and J14 is a much more sophisticated concept.
Also, the visco unit in the J8 (not sure about J10) is rated as '20%'....which means it can redistribute 20% of max torque in 1st gear high range (since in low range the center diff is mechanically locked, at least in factory configuration (easy to modify, to have an open center diff also in low range)

Not sure which brands/models have a 33/66 transfer case, with sufficient torque-rating, perhaps the Mitsu Pajero in one of the later configurations?
(it does have a nice range of 2wd/4wd-open/4wd-locked, not found on any other vehicle I believe)


Zitat:
Zitat:
Note that a visco-LSD on top of a 50/50 center diff doesn't really change that behaviour, it only limits wheel spin when, after and as long as slip occurs....the initial breaking of traction it can not prevent, and that is what counts in corners.



Thank you for reminding me about the quotations, Chris had given me a coaching session with it a few weeks ago but I am not using it often and so I am not very fluent with it, so I forget, its my age, well that is my excuse and I am sticking with it grin grin.

It works grin grin


Hmm....but right now I have the feeling you are reverse-quoting, putting the reply above the quote....a common anomaly when people only reply once on a quote (lazily starting to type where the cursor is located), but rather weird with multiple quotes....8-))

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Re:Emergency Braking C303/304/306
« am: 10.Dezember 2007 23:54:28 »
Antwort mit Zitat nach oben
Zitat von: Anthony am 10.Dezember 2007 23:12:55
My dear Chris,

The TGB 13 is part time 6x6 and putting it into full time 6x6 would be just the same as locking the central differential of a modern 4x4 such as in a Landrover.  In essence there is then no differential movement allowed it is exactly just the same, the axles would be locked together. As you so aptly put it one would be f--d going into corners.

I did on my way home to GB try the brakes hard and yes I could hear the vacuum activator hissing but I doubted very much that the front axle was ever engaged.  I suspect that it is slow to come in and therefore possibly sow to go off.



Nope, it is lightning fast, and you won't hear anything else than the hissing, *unless* you also create drive-line binding.
Try it in a corner, then straighten out....you will hear a clunk.

Btw, I was pondering about a test with the front axle on a hoist, you could do that not just with the engine off, but also with running engine and the T-case in neutral (bit harder on military versions, since the dash indicator lacks the 'N' that civil models have))....just to rule out some vacuum-related problems, having a constant vacuum supply.

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Re:Emergency Braking C303/304/306
« am: 10.Dezember 2007 23:55:12 »
Antwort mit Zitat nach oben
Zitat von: Anthony am 10.Dezember 2007 23:12:55
My dear Chris,

The TGB 13 is part time 6x6 and putting it into full time 6x6 would be just the same as locking the central differential of a modern 4x4 such as in a Landrover.  In essence there is then no differential movement allowed it is exactly just the same, the axles would be locked together. As you so aptly put it one would be f--d going into corners.

I did on my way home to GB try the brakes hard and yes I could hear the vacuum activator hissing but I doubted very much that the front axle was ever engaged.  I suspect that it is slow to come in and therefore possibly sow to go off.



hi anthony.
its front-to-rear diff lock and not left-right lock so i still do not see where a front wheel would spin faster or slower than the rear axle wheels or am i just to blind to see the fact? can you enlight my rusted brain as i do not get it by now...
when front and rear is locked still left side and right side can spin differently and though can come around corners easily. (thats my assumption where i may be wrong?)

sorry for nerving you on this and yes i may be wrong... grin

greets,

chris (who may better go off to bed)
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Re:Emergency Braking C303/304/306
« am: 11.Dezember 2007 00:42:9 »
Antwort mit Zitat nach oben
Chris,

If you get into a Landrover Defender this is permanent all wheel drive as the centre diff allows a speed differential to exist and drive it without operating the central diff lock in the transfer box all is well when driving on the highway.  If you then operate the centre diff lock in the transfer box on the highway it will not then allow for any difference in speed between the axles.  In a very short distance one would notice the steering fighting and then the car would start to crab along the road and it would very soon start to weave about.  When then trying to negotiate a bend there would be a marked reluctance to turn smoothly.  The steering would become very heavy and one would have to fight it around.  In the snow or off road it would be all OK but on the hard surface of a highway the axles would start to become wound up and it would become very obvious from not only the effects that I have described but also from the audible complaints from the transmission that all is not well.  Eventually a brakhage may occur in the transmission system. 

If you were then to drive a series landrover it is normally on the highway in 2x4 or rear wheel drive.  If you were then to put the transfer box into 4x4 it would be in 4 wheel drive and would be exactly like the landrover Defender and would behave on the highway in just the same manner with all the ill effect described above.  The Volvo TGB would also behave in the same way as above if it was put into 4x4 or in the TGB 13 case 6x6 so normally on the highway it is only rear wheel drive 2x4 or for TGB 13 4x6.

I agree if an axle lock were applied the results would be very much worse but believe me one does not want to be in permanent 4x4 or 6x6 for very long on a hard surface such as a highway.  There is always a small difference in speed between axles especially as tyres become used or on or more tyres have a different tyre pressure there is a small difference in diameter.  Every time one goes around a corner the front wheels turn a slightly different amount than the rears.  Also the inside turns slightly differently to the outside.  If the front axle is engaged to make it 4x4 or 6x6 or in the case of a modern all wheel drive vehicle having its centre diff locked then those differences cannot be cancelled out and we get the problems as described.

If you do not believe me, engage your front axle put it in 6x6 next time you go out on the highway and leave it on, see how far you get before you want to turn it off.  It will not be long especially if on a winding road but even on the strait it will not like it for very long.



Zitat von: Chris am 10.Dezember 2007 23:55:12
Zitat von: Anthony am 10.Dezember 2007 23:12:55
My dear Chris,

The TGB 13 is part time 6x6 and putting it into full time 6x6 would be just the same as locking the central differential of a modern 4x4 such as in a Landrover.  In essence there is then no differential movement allowed it is exactly just the same, the axles would be locked together. As you so aptly put it one would be f--d going into corners.

I did on my way home to GB try the brakes hard and yes I could hear the vacuum activator hissing but I doubted very much that the front axle was ever engaged.  I suspect that it is slow to come in and therefore possibly sow to go off.



hi anthony.
its front-to-rear diff lock and not left-right lock so i still do not see where a front wheel would spin faster or slower than the rear axle wheels or am i just to blind to see the fact? can you enlight my rusted brain as i do not get it by now...
when front and rear is locked still left side and right side can spin differently and though can come around corners easily. (thats my assumption where i may be wrong?)

sorry for nerving you on this and yes i may be wrong... grin

greets,

chris (who may better go off to bed)
Grüße


Anthony
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Re:Emergency Braking C303/304/306
« am: 11.Dezember 2007 00:51:53 »
Antwort mit Zitat nach oben
WJM, I have considered you comments on the ideal torque distribution for the TGB 13 if using all wheel drive on road.  It might well be that an asymmetric torque split might be ideal, but if this were simply a 4x4 then we might want 50/50%,  The rear of TGB 13 has two axles sharing the load, so perhaps one might then wonder if a 50/50% split at the transfer box is still ideal.  We would then have starting from the front axle 50/25/25% possibly.  If the rear two axles share the load then what is wrong with them sharing the torque, they do any way.  In the mode as we have it know on road we have all of the available torque going to the rear a 0/100% distribution for a 4x4 and for a TGB 13 a starting at the front axle 0/50/50%

This is all assuming that the rear two axles do in fact share the load at all times.  The rear two axles are locked together I believe.

A torque split as you suggest 33/66 would amount to giving an overall split for a TGB 13 of 33/33/33 to the axles, this looks OK but it is putting a 66% torque bias to the rear.  After all off road with every thing as it is today when one goes into 6x6 or we get a 50/50 split at the box and a distribution of from the front 50/25/25 and it does not feel like front wheel drive.

I shall have to retire from the field for the night as I have been told off twice already by the one whom should be obeyed, evidently my bashing of the keys is keeping her awake.  So good night to you all smiley sleep well.
Grüße


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Re:Emergency Braking C303/304/306
« am: 11.Dezember 2007 14:28:27 »
Antwort mit Zitat nach oben
Zitat von: Chris am 10.Dezember 2007 23:55:12
Zitat von: Anthony am 10.Dezember 2007 23:12:55
My dear Chris,

The TGB 13 is part time 6x6 and putting it into full time 6x6 would be just the same as locking the central differential of a modern 4x4 such as in a Landrover.  In essence there is then no differential movement allowed it is exactly just the same, the axles would be locked together. As you so aptly put it one would be f--d going into corners.

I did on my way home to GB try the brakes hard and yes I could hear the vacuum activator hissing but I doubted very much that the front axle was ever engaged.  I suspect that it is slow to come in and therefore possibly sow to go off.



hi anthony.
its front-to-rear diff lock and not left-right lock so i still do not see where a front wheel would spin faster or slower than the rear axle wheels or am i just to blind to see the fact? can you enlight my rusted brain as i do not get it by now...
when front and rear is locked still left side and right side can spin differently and though can come around corners easily. (thats my assumption where i may be wrong?)

sorry for nerving you on this and yes i may be wrong... grin

greets,

chris (who may better go off to bed)


I agree with Chris here....locking a center diff has rather minor effects on steering, unless you take the tightest corners possible.
Note that I have driven my LWB C306 with a faulty/locked T-case for about 1000km, without realizing something was terribly wrong....this was even *before* I had power steering added....just a bit *more* sluggish in tight corners, but not excessively....possily (as I wrote before) the result of a rear tandem set of wheels that are already scrubbing, allowing the overal drive-train binding to 'dissipate' as well).



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J.R.R. Tolkien
...and not all who launder are washed/WJ....;))


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Re:Emergency Braking C303/304/306
« am: 11.Dezember 2007 14:34:18 »
Antwort mit Zitat nach oben
We are starting to go off subject just a little For Rangerover gearboxes take your pick of these

http://www.quaife.co.uk/LAND-ROVER-ATB-DIFFERENTIAL

I like this
http://www.quaife.co.uk/Land-Rover-Range-Rover-Quaife-uprated-6-speed-sequential-gearbox

I guess I like a LSD that can be locked just like the Landcruiser 80 and some of the Rangerovers.  In fact I like the set up of the Landcruiser 80 4.2 TDi Engine + Gearbox + Transfer Box, but it is a bit heavy.  I have adapted my Landcruiser transfer box to remain open when in low box so I have to manually lock it.  One only has to snip a wire or two to achieve this and it is very worth while.  The Rangerover/BMW 6cyl Engine + Gearbox + transferbox might be better especially the 3 Liter version.  Any way that s for another topic not this one.

I have discovered reading through the manuals thoughtfully provided by Michael on this site that in fact the TGB 13 does in fact have some reduced braking at the rear axles just like many other vehicles.  This is because each rear drum only has one leading shoe as there is only one brake cylinder, so I am a little happier knowing this.  I still think that I would prefer a load proportioning valve like the Pinzgauer and most other vehicles of this type.  The 6x6 Pinzgauers only appear to have one LPV at the rear axle on one side.  Of course the Pinzgauer has independent swing axles so the geometry is different but I am sure something could be done with a LPV somehow.
Grüße


Anthony
GB
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Re:Emergency Braking C303/304/306
« am: 11.Dezember 2007 14:36:44 »
Antwort mit Zitat nach oben
Zitat von: Anthony am 11.Dezember 2007 00:51:53
WJM, I have considered you comments on the ideal torque distribution for the TGB 13 if using all wheel drive on road.  It might well be that an asymmetric torque split might be ideal, but if this were simply a 4x4 then we might want 50/50%,  The rear of TGB 13 has two axles sharing the load, so perhaps one might then wonder if a 50/50% split at the transfer box is still ideal.  We would then have starting from the front axle 50/25/25% possibly.  If the rear two axles share the load then what is wrong with them sharing the torque, they do any way.  In the mode as we have it know on road we have all of the available torque going to the rear a 0/100% distribution for a 4x4 and for a TGB 13 a starting at the front axle 0/50/50%

This is all assuming that the rear two axles do in fact share the load at all times.  The rear two axles are locked together I believe.

A torque split as you suggest 33/66 would amount to giving an overall split for a TGB 13 of 33/33/33 to the axles, this looks OK but it is putting a 66% torque bias to the rear.  After all off road with every thing as it is today when one goes into 6x6 or we get a 50/50 split at the box and a distribution of from the front 50/25/25 and it does not feel like front wheel drive.

I shall have to retire from the field for the night as I have been told off twice already by the one whom should be obeyed, evidently my bashing of the keys is keeping her awake.  So good night to you all smiley sleep well.




You are wrong on 2 points:
1) torque-distribution should equal axle/wheel-load distribution....which is 33/33/33 in case of a loaded 6x6
If you have a load-distribution of 33/33/33, but a torque-distribution of 50/25/25, then your front tires have a much higher chance of spinning, both acellerating and decellerating/engine-braking (unless steep downhill of course, in which case the load-distribution would be close to 50/25/25 too)

2) torque-distribution can only be given for open diff's; once you lock a diff, the ratio can change wildly from 0/100 to 100/0, all depending on which axle/wheel as grip or not


Addendum: you do not want to sent torque/power predominantly to the 'weakest' front axle, with the CV-joints....it would increase wear in the most expensive/labor-intensive spot....in that context, even a 20/80 distribution makes sense (even more so on steep hills).






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...and not all who launder are washed/WJ....;))


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Re:Emergency Braking C303/304/306
« am: 11.Dezember 2007 14:39:11 »
Antwort mit Zitat nach oben
I thought that we exhausted that particular point about the 1000km on an other forum when you eventualy admitted after a long debate that it was not on tarmac or hard surfaces.

Zitat:


I agree with Chris here....locking a center diff has rather minor effects on steering, unless you take the tightest corners possible.
Note that I have driven my LWB C306 with a faulty/locked T-case for about 1000km, without realizing something was terribly wrong....this was even *before* I had power steering added....just a bit *more* sluggish in tight corners, but not excessively....possily (as I wrote before) the result of a rear tandem set of wheels that are already scrubbing, allowing the overal drive-train binding to 'dissipate' as well).




Zitat:
Grüße


Anthony
GB
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Re:Emergency Braking C303/304/306
« am: 11.Dezember 2007 15:23:26 »
Antwort mit Zitat nach oben
I made an error on the distribution of load I can see that.

According to http://www.tgb-sidan.se/1c3data.html

Curb wt Front axle 1290kg Rear bogie 1530kg  =  1290/765/765  rear axle 27% = 46/27/27%

Max wt Front axle 1700kg Rear bogie 30000kg =  1700/1500/1500 rear axle 32% = 36/32/32

So therefore ideally the power split should represent that so the torque bias at the transfer box would ideally range between a

27/54% split and a 32/64% split
Grüße


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GB
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Re:Emergency Braking C303/304/306
« am: 11.Dezember 2007 15:53:0 »
Antwort mit Zitat nach oben
Zitat von: Anthony am 11.Dezember 2007 14:34:18
We are starting to go off subject just a little For Rangerover gearboxes take your pick of these

http://www.quaife.co.uk/LAND-ROVER-ATB-DIFFERENTIAL

I like this
http://www.quaife.co.uk/Land-Rover-Range-Rover-Quaife-uprated-6-speed-sequential-gearbox



Interesting, didn't know they had offroad/T-case versions of their sequential gearboxes.
However, aren't those the very harsh non-clutch type?

Zitat:
I guess I like a LSD that can be locked just like the Landcruiser 80 and some of the Rangerovers.  In fact I like the set up of the Landcruiser 80 4.2 TDi Engine + Gearbox + Transfer Box, but it is a bit heavy. 



No, it is perfect, because it was (also) made for the 5-7 ton Dyna/Coaster....:))
Nothing wrong with a truck box, even less with such a strong engine behind....;))

Zitat:
I have discovered reading through the manuals thoughtfully provided by Michael on this site that in fact the TGB 13 does in fact have some reduced braking at the rear axles just like many other vehicles.  This is because each rear drum only has one leading shoe as there is only one brake cylinder, so I am a little happier knowing this. 



Ah yes, of course....including the fact that the dual-booster circuit is split in a 2x triangle with front bias (and rear axle/axle split).
(which, by means of the intercoupled rear axles, means that any brake-effort on the rear is nicely spent on all 4 rear wheels)

Zitat:
I still think that I would prefer a load proportioning valve like the Pinzgauer and most other vehicles of this type.  The 6x6 Pinzgauers only appear to have one LPV at the rear axle on one side.  Of course the Pinzgauer has independent swing axles so the geometry is different but I am sure something could be done with a LPV somehow.



Unless you invent something to level out the bogie-movement of each axle in opposite up/down direction, you have a nightmare on your hands....8-))



*Verkaufe Battery-Equalizer/Charge-Balancer/Wandler 24->12v/100A*


Those who wander are not necessarily lost
J.R.R. Tolkien
...and not all who launder are washed/WJ....;))


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