Slowing down with Cruise Control on..?

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Mon 4 Nov 2002 14:50
Slowing down with Cruise Control on..? - Chad.R
How does a cruise control system cope with a steady and relatively long slope?

What prompted this train of thought was travelling down the A41 on Sunday from Aylesbury towards Watford, there's a 2K section which has a fairly steep and steady slope. I was in the Omega(auto) doing around 50mph at the "top" and it started to gather speed fairly quickly, even in a manual car you'd have to use the brakes or shift down, not to exceed 80+'ish at the bottom. (Though the roundabout there helps prevents this too!)

How would a modern cruise control system cope with conditions like this (assuming you don't disengage it) - AFAIK it's not connected to the braking system so would it just let the car gather excess speed?

Chad.R

P.S I know the Driver would have to be asleep not to notice - the questions purely hypothetical.



Chad.R
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Mon 4 Nov 2002 15:56
Slowing down with Cruise Control on..? - Mike H
As you say, cruise control only affects throttle settings. Once it has attempted to slow the car down by backing the throttle right off, it won't do anything else therefore, as you say, the car continues to gather speed until you brake, or change gear. Both actions will cause the cruise control to disengage (assuming it's a manual gearbox, not sure about an auto as I've never had cruise on an auto).

Theoretically, it could presumably be linked to the brakes but the only car I'm aware of where it might do this (someone else might have more info, and correct me if I'm wrong) is the new E-class.
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Mon 4 Nov 2002 16:58
Slowing down with Cruise Control on..? - terryb
My old XM auto used to use the engine braking, changing down if necessary. Pretty sure the Gr Cherokee does too.

with a manual box of course it wouldn't be able to do that....
Terry
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Mon 4 Nov 2002 17:23
Slowing down with Cruise Control on..? - Phil G
The cruise on my Carlton will kickdown uphills, albeit grudingly.
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Mon 4 Nov 2002 19:49
Slowing down with Cruise Control on..? - RogerL
Cruise control with auto has the advantage of NOT disengaging when changing gear, unlike a manual with CC. This applies whether the box changes automatically or in override.

Downhill the CC will shut the throttle as far as necessary. If it's fully closed and you're still going too fast, just override into 3rd, or even 2/1 if necessary.
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