I'm not sure if I use the right term by hill stop assistant but what I mean is:

How is it technicaly done that the car while running in D mode and in steep uphill stops (eg. red light in the middle of a hill) and does not move backwards without pressing any brakes at all??? I assume the tranny is engaged to the rear axle/ wheels somehow but the clutch disconnects it from the running engine somehow???? just curious it is definitely not done by any brake force. It is some kind of clutch/tranny combo working

Any serious real tech answer?

 

Hi peter 530,

I think, the hillhold function works like this: with the motor running, the electro-mechanical handbrake working on the rear wheels is activated by the hydraulic DSC pump. Activation and release are electronically managed.

 

the E60 has an electronic handbrake? Are you sure?
Isn't it the classic one with the string tied from the handle to the rear brakes??? Because all the cars with electronic handbrake have a button for it not a classical lever like the E60....

Also it still does not sound right to me that it woud be the actual brake (brake pads) holding the wheels at this mentioend situation

 

I thought the gearbox or so...has a sensor that detects the incline of the car, especially when facing uphill. It then uses just the amount of torque through the torque converter to hold the car in steady position. That's what i think and know about this...
Think about it when you are in D mode and on normal road you take away the foot of the brake (let's say at a red light) the car moves away slowly but in a just slight acceleration. Well that's because the usual amount of torque sent through the torque converter at idle rpm. When you are just slightly uphill, but just slightly, u'll see that the car will start to move away but this time harder since the same ammount of torque needs to fight the incline. When you are seriously uphill you'll notice that especially when you shift quite fast from P to D (considering that you parked your car in an inlcimbe situation) the car will lurk downwords but just for a few cms, and as soon as the torque gets to fully pass throught the torque converter (the same ammount at idle) the car will remain standstill without touching the brakes. If you shift way slower, like waiting a bit in R and then a bit in N (total of 2-3 seconds or so) and then shifting to D you'll see that the car will not lurk downwords anymore and it will remain standstill after you left your foot off the brake. That's because it had enought time for the ammount of torque to start flowing thorught the torque converter. That's my explanation anyway...

 

BetterMakeWay sounds like you are on the right track with this idea ....
it is somewhere around there like this

 

Continental Automotive Systems provides brake technology for BMW and here is how the hill assist works in detail: http://www.conti-online.com/generator/www/...ics/hsa_en.html

 

So, same system for manual or Step? Clever