Engine protection device??? electrical "box", lockout to prevent wrong gear choice?? Options

[Mueller]

We don't read about people shifting into the wrong gear too often which ends in costly repairs, but when we do hear about it, it gives everyone a sick feeling knowing that big money is about to be spent.

Now it seems it wouldn't be too difficult to have a "box" that monitors engine RPM as well as what gear the driver is in and MPH. Of course the "box" is going to have to have some logic control with user inputs for different variables.

Basicly what we want to do is have the "box" tied to an electrical/mechanical device that will not allow you to put the car into a gear which the "box" has deemed unsafe.

So if you are in 4th @ 6500 and want to go to 3rd which will raise the rpms to 7000 (borderline redline)
the "box" will "okay" the gear choice and not interfer....well, due to some odd reason, the driver picks 2nd gear instead, the "box" knows that 7500 rpm is way too high and it gives a signal to the electrical/mechanical device and "blocks" the gear selection.

Now the only way the driver can put the car into a gear is: Stay in 4th or, shift into 5th or slow the car down enough so that the road speed will match the RPM/gear/MPH safety combination which is the "box" will be programmed for.

This is nothing new, Porsche used this logic on thier PDK transmission and RUF had this for his clutchpedal-less manual shifting cars.AFAIK, no one has this as an "add-on" device or to be used with a clutch pedal

[lapuwali]

I can't think of a single instance where downshifting will save you from a collision. This is tantamount to a biker insisting they had to "lay her down" (which is a completely silly concept I'm not even going to bother to argue). If you're using the gearbox and clutch as a brake because of brake failure, use the handbrake instead. If both your hydraulic system and the handbrake have failed, I suppose that's it's slightly possible a downshift might help, but that's got to be a pretty rare case.

To Mike's point, I'd think this would be fiendishly difficult to implement. How do you prevent the clutch from engaging? How do you detect which gear the car is in? Neither of these are trivial problems to solve reliably. It's much easier to do gear detection with something like a sequential box, where a simple up/down microswitch can detect shift drum movement. Not so easy on most H-pattern 'boxes. On the clutch, some solenoid/pin arrangement is the only thing that leaps to mind, preventing the clutch arm from moving far enough to release the pressure plate. On the gear detection, supplying a Ferrari-like gate at the shift lever and using switches to detect position in the only thing I can think of that could be done at a reasonable cost.

I'll have to dig it up, but in a back number of Racecar Engineering, they described what I have to say is the most brilliant gearbox idea in quite some time. Imagine, instead of the synchro/slider/dog gear system, you had a set of small hydraulically actuated multiplate clutches (hydraulic fluid acting directly on a pressure plate inside a housing splined to the shaft, just as the slider is). Think of several little brake pistons pressing against the gears to tie them to the shaft. These little clutches can be operated by (relatively) inexpensive solenoid valves, which can be computer controlled. To engage a gear, just open one of the valves. To engage neutral, close all of them. Not a complicated control program.

Now, there's no more dog ring/gear/synchro wear, as those parts are gone. By varying the speed at which the valves open, you can have the shift action be slow and smooth, or quick and hard. If the hydraulics fail, the system either remains in gear (as long as the pipe between the engaged clutch and the valve isn't the leak), or goes into neutral. If the electrics fail, all of the valves open, and the 'box goes into neutral. Since there's a computer controlling the valves, it's easy to program in rev limits. You could arrange it as a "pre-selector", so you push a lever, say, 2 times when in fourth, and the computer shifts down to second only when the revs are matched to your speed, rather than exactly when you push the lever. The main clutch would only be used for starting from a stop, and wouldn't have to be touched otherwise. The best thing is it can be retrofitted into nearly any existing gearbox.

Some Australian engineering student dreamed it up, and made a prototype or two, used in some racecars (rally cars, I think). Last I heard, he was looking for a manufacturing partner to make them in quantity. I think it's revolutionary, but unfortunately, it doesn't look to be attracting anything like the attention it deserves.