no it doesn't. at all.

no idea what you're referring to with 'sometimes', 'other factors', etc. CVTs are ALWAYS more efficient than both manual and automatic gearboxes.

ditto except i respectfully disagree with all of yours.

and the article backs up precisely what sulu and i have both said. and the article is also about the PERCEPTION of droning (or maybe lag) from the SOUND of the engine running at constant rpms while the gearing changes, which has NOTHING to do with lag in acceleration.

 

Just because we can measure an incoming data stream in binary language, doesn't mean we have to display it as a series of moving numbers. Digital instruments were "fashionable" back in the late '80's when everyone decided it was the "high-tech" look of the future, but I worked with the developers of an instrumentation system back then and we found it had a very serious problem - it doesn't relate well to human beings when trying to interpret a rapidly-changing situation.

Imagine an instrument in front of you, say a tachometer that displays digits only. As the engine revs quickly, it takes you a moment to grasp what is going on under the hood. Your eyes catch the number "3", and a split-second later, the number "5". OK, fine - but your brain has to quickly interpret the fact that "5" is a larger number than "3", therefore the quantity being measured is rising. Then it has to decide whether that is good or bad. On the tach, is "5" safe? We have to think back to the owner's manual to decide whether "5" means something expensive is about to happen, and the relative time required to progress from "3" to "5" may mean disaster is already in the rear-view mirror . . . as in that cloud of oil smoke following you.

Water temperature is "240°" . . . again, good or bad? Is it increasing or decreasing? The same thing can happen with oil pressure - obviously "0" is not good, but where's the lower acceptable limit, and have you reached it yet? Remember, instruments can only tell you history - not always what's happening in the engine room at this very instant. Engineers try to damp out small excursions in the readings - you don't want to see your engine temperature rise and fall as the thermostat opens and closes - or read every slosh in your fuel tank - that would really be confusing.

The primary purpose of any kind of instrument display is communication - not necessarily with other binary devices, but with that grey lump of flesh between our ears. Our brains have to recognize and interpret inputs, and that takes a bit of effort. Scanning the instrument panel should be simple - communicating instant information. Most designers of instrumentation systems subscribe to the convention that all the needles pointing up means you are in good shape - with some allowance for a bit right or left of vertical saying all is well. A needle on the peg - either maxed or dead - is VERY bad news. We determine this by its relative position on the scale - we can go back and read off the numbers if we need to - if we are under a steady-state condition where accuracy is required, but a quick scan of the instrument panel should instantly communicate what's happening out front, and which is important to us.

NASCAR's Sprint cup cars mandated a digital dash recently, and drivers adapted rather quickly - but now the instrument readings are being relayed to a team of engineers in the pits via real-time telemetry - who can take the time to study the digital information that includes a variety of temperature and pressure readings and assemble a strategy out of the flood of numbers coming in. Is it more helpful to the drivers? Probably not, but most drivers spend their time looking out the windshield and let the engineers watch the tire pressures and brake temperatures anyway. Flashing numbers or a change of a display color works well to grab the driver's attention, but it may be a while before we see that level of sophistication in regular production automobiles. The same thing happened in F1 where the driver is only aware of a series of warning lights, his instruments are being read by engineers in the pits.

Think of it this way, with just a glance, which means more to YOU:


or:


An oilfield instrumentation company I worked with had produced a large panel of extremely accurate LCD digits to help keep the driller informed of what was going on with the rig. It turned out that in an emergency, numbers speeding by on the screen were not helpful. OK, if you were measuring three digits, you could probably handle it eventually, but 7 digits was just showing off. Wait a minute, did my hook load indicator just go from 640,421# to 661,976#? To be sure, it was very accurate, but with those numbers in the right-hand window screaming by at a rate that made them and a couple of their neighbors turn to a blur, you really couldn't see the trend of the reading until it got into maybe two or three significant figures. It turns out in most cases that trend is more important than the actual numbers themselves.

The manufacturer eventually had to put a status bar alongside each digital display simply to inform the operator whether the numbers were increasing or decreasing rapidly because a spinning four-to eight digit display was meaningless. In a disaster scenario, it was a matter of life and death - not just whether you were going to void your warranty. They ended up with a panel that had at least two readouts for every function, one digital and one simulated analog, plus color-coding that would flash yellow or red to draw attention to the most critical changes taking place. All of this was to replace a simple set of needles and numbers. Digital readouts just didn't work well with humans.

There is a good reason that wristwatches that once went to digital displays came back to three hands. Sure, if you were asked the time you could say "It's 11:45:42." with great authority - but you had to think about it for an instant to determine it was just under 15 minutes 'til lunch. That's the problem with digital readouts - humans are relational in their thinking - we need to see numbers in a context that is meaningful. If the temperature gauge is in the green, that's good. If it says "240°" we have to think about pressure and bring in a couple of Gas Law equations to understand something's about to let go. Sometimes an analog display is "close enough". It's how we interpret things quickly.

Digital displays look futuristic and produce very accurate readings but they aren't always meaningful in an emergency because they don't work well with humans - even less well where mission-critical instruments that require instant communication and decisions are involved.

 

But the examples you are citing for RPM and temp is for data that most drivers don't normally pay attention to, and so don't know what's good or bad, except in the context of a needle moving up and down, and seeing a red zone. You can't use this argument for the speedometer--people know what's fast, and what's not, and what's over the speed limit and what's not.

 

Well, OK...except that I wasn't the one who first came up with the term "motor boating" for typical CVT action. It was the people in the auto press, and, to some extent, the engineers.

 

BTW, Bob (Lil4X)..........as usual, an excellent post. What you described is EXACTLY what my experience has been over the years.

 

there are an equal number of counter examples to what you write... for example, almost no kitchen stoves have rotary/needle displays for temperature, time, etc. any longer, and no one is confused by these. my clothes washer and dryer each digitally show how much time is left on the cycle. almost all bedside clock/radios use digital displays. most coffee makers use digital displays. i had one cuisinart that had an analog clock display and i hated it. i guess it's because i'm 'bit' kahuna, ha

as you've said, there's plenty of ways to raise the alarm with digital displays, with colors, flashing/animation, vibrations, and sounds. a needle getting into a 'zone' on its circular motion isn't really any 'better', except in old movies where the submarine's depth and pressure dials are all at 5 o'clock with needles shaking - but the sub's CREAKING is a better indication.