Does anyone know how "cruise controls" work ??

[Die Judicii]

Have been wondering for a while about this.

Do they operate by utilizing speed as in,, klms per hour,,,,,,, or, do they use rpm as the basis ????

[Blr243]

When I had one fitted years ago they tied magnets to my tail shaft And there was a sensor next to the magnet registering the revolutions .....and from there on it was wires and electrics and u know But that was 15 20 years ago

[bladeracer]

Have been wondering for a while about this.

Do they operate by utilizing speed as in,, klms per hour,,,,,,, or, do they use rpm as the basis ????

They operate off whatever speed sensor the vehicle uses.

[duddley75]

I would imagine it is speed based. As you can set cruise control in different gears (manuals transmissions etc). The same speed in different gears would have different RPM'S.

Also in an auto if you transition from uphill to flat the RPM's are going to drop off as you level off.

[scoot]

Besides the old bangers that have a Speedo "cable", most all use a variation of magnetic pulse to detect speed (both dash and abs, stability control). The pulse is used by control computers in your car to then display speed in km/h, stop wheelspin or lockup for abs sensors, rpm of engine with crank sensor or to maintain the constant speed of the vehicle for cruise control.

[scoot]

Most cruise will use the input from abs sensors on each wheel, gearbox/transmission output speed (ie tailshaft speed and hence diff speed and wheel speed) or a combination of both.
Problems arise when big wheels or changing diffs, etc. The "system" is then not calibrated.

[SomeoneElse]

Complete conjecture, but as I understand it:
- Cars with single speed sensors (e.g. one non-driving wheel) will typically rev the engine through the roof when you aquaplane. When the vehicle speed slows down it tries to compensate but the lack of traction means it over-compensates and revs the engine hard. When traction is eventually gained you're putting a fair bit of power in a now-random direction. These cars typically have a warning to not use CC in the rain.
- Cars with traction control have multiple sensors (e.g. one on each wheel, which may serve dual purpose for ABS, etc), can discard "outlier readings", and probably compare if drive and non-drive wheels are within expected range of each other. I think this is how my current works, and there is no warning whatsoever re using CC in the rain.

Someone Else.

[Blr243]

My hilux is an auto I only use cruise control on hunt trips ....when in top gear ( possibly also called over drive ) I will be set on 102 klm per hour and if I encounter any sort of slope and a gear automatically kicks back the cruise control utomaticly adjusts very quickly to maintain constant speed ....mine is 2010 model .....I tend not to use cruise control if the Roos are bad it takes me too long to react

[Die Judicii]

.....I tend not to use cruise control if the Roos are bad it takes me too long to react

How so ???

If your using cruise control your right foot is free to hit the anchor even faster.

[bigrich]

i think older stuff like hz and wb statesmans and fairlanes used to use engine vacum once the vehicle was in top gear . i think other systems used a sensor on the fly wheel/flexplate . all the modern systems are off the abs sensors in the brakes or really advanced systems use computer gps management . lot of different ways to do it . i don't use it myself, i think it can make drivers complacent

mind you , i remember a mate of mine saying how many years ago in the late 80's , him and some mates set up cruise control on a slant six valiant safari wagon on a road trip through central australia

they simply drilled a hole in the accellerator pedal and cut a tent pole to the right size to fit between the pedal and the bottom of the dashboard

[Blr243]

I think I don’t like cruise around Roos because around Roos I need to b really paying attention and be totally switched on.....I only turn on the cruise when I have a long brain dead boring stretch of road

[TassieTiger]

My effing bike has cruise - I ve over taken cars, waving with my right hand at the kids - you can tell the bike riders...mums wave back but bike riders look and go WTF?!