Launch speed

They don't need all of those sensors with 6 trains since 2003 when dry mode was taken out of the program. They can run 6 without the sensors, but the ride is less efficient than with 5. I don't know exactly why they put the 6th on everyday outside of test riding it so they can swap trains quickly if needed for a bad wheel or other train issues.

Okay Adam, how many days until May 12. :)

Jump to conclusions,

When I first saw the set-up on TTD I had a feeling that they way over did it on the proxys. Now the question that I have is that you said that it is only looking for one sensor, how does the PLC determine a bad proxy fault? You would need a double proxy set up (redundancy back-up) to determine a proxy fault would you not?

I have been doing controls for a while now and have never liked proxys, they are to prone to voltage spikes causing them to freeze make or break. The ones they are using appear to be IFM Efectors which is a good name but they generally have a broad sensor range which can cause bad signals if not alligned properly. Is this the common issue on TTD?

Give me an old mechanical limit switch from Honeywell any day of the week over a Proxy. In this situation there is no need for the added exspense of a proxy.

^^Hey Im learning some neat (though useless to most people) info here.:) Like that the computer adjusts the pressure and not the ops like I originally thought (but now that I think of it, I dont know why I always thought that).

And I remember experiencing unusually long amounts of downtime in 04 due to those little green proxies.

Oh and there's 127 more days to go.:)

*** Edited 1/5/2007 4:02:43 AM UTC by TTD 120mph***

Jump to Conclusions said:

A car engine has peak HP. You can run it momentarily at such power. Run it at peak power for more than a little bit continuously and the engine will explode. Aggressive use of a car engine will lead to premature engine failure. High RPMs put extreme forces on the reciprocating parts. Most stock engines are not designed to handle high RPM's for more than a few short periods of time.

Sort of. A car engine does have peak horsepower, but never tuned to actually put down that hp in a stock product. For example GM's eco-tec 2.0 4 cyl is capable of putting down 1,000 hp at the flywheel yet delivered to the showroom with no more than 260 hp currently.

Most vehicles are however designed to run at peak (or stock) hp for extended periods of time. Using that very same engine, it will reach peak hp @ 4600 RPMs and hold it for several thousand miles. (with proper maintenance) A CVT (continuously variable transmission) will keep an engine at peak performance for extended periods of time as well.

Look at Top Fuel Dragsters, F1, Kart and even NASCAR vehicles. They run at peak hp 90% of the time.

Honda's little 4 banger in the Civic does not have a stock redline. just a limiter keeping you from going over 8K RPMs.

However constantly redlining will cause premature engine failure, but usually only by a few thousand miles. Redlining does not deliver peak hp.

David Sagert said:
Now the question that I have is that you said that it is only looking for one sensor, how does the PLC determine a bad proxy fault? You would need a double proxy set up (redundancy back-up) to determine a proxy fault would you not?

Most of the proxs used on TTD are in pairs. A Master and a Safety. I believe the Master is NO and the Safety is NC. There are a few that are by themselves for example the approach proxs. They fail both ways so in the program it have logic to find both faults. Every time a block cycles from clear to occupied back to clear, the control system checks each prox. There is a set of lines in the program that latch when a prox is triggered. When the block is cleared by the block reset proxs, the lines of code look to see if all of the proxes latched or not, if not it will set a fault code indicating which prox did not trigger during the cycle. All proxs must cycle or it is known that there is a problem with the prox.

David Sagert said:I have been doing controls for a while now and have never liked proxys, they are to prone to voltage spikes causing them to freeze make or break. The ones they are using appear to be IFM Efectors which is a good name but they generally have a broad sensor range which can cause bad signals if not alligned properly. Is this the common issue on TTD?

They fail from time to time in both states. Alignment is not as big of an issue on Dragster as other applications but they do have to be within a certain tolerance to aviod knocking them off or not triggering properly.

David Sagert said:Give me an old mechanical limit switch from Honeywell any day of the week over a Proxy. In this situation there is no need for the added exspense of a proxy.

I perfer solid state. :)

^Thanks, wasnt trying to get you on anything I was just wondering since you said the PLC was only looking for one proxy. I figured that they were in a double redundency format when I first laid eyes on the number of proxys present.

Funny story though, first time I rode TTD I was with the Maint. guy from where I work and when we both noticed the proxys we both said "man I hate those things they always break". Not 20 min. later Maint. was out replacing a bank at the end of the brake run / brake hold area.

No offense taken.

I'm kind of confused where I said that the PLC is only looking for one proxy though. There are some on the layout that are by themselves but they don't really need to pair the few in that case. I did mention sensor rows, implying more the position (there are 4) of the proxs as opposed to a single prox.

I missed Coastern3rd's post

Most stock engines will have an engine failure in a fraction of the time if they are frequently ran to their rev limiter. I've personally seen the damage that is done to such engines. Of course some car engines are built for racing applications and can deal with the high RPM and heat issues. Stock engines try to run at the stoichiometric 14.7:1 air/fuel ratio for gasoline. It runs very hot and requires bypass gas from the exhaust to limit the fuel mixture in the engine. Racing applications run richer for the higher power, and cooling effect.

^ not to mention that race engines run higher octane fuel which burns better and not as hot

Jump to conclusions,

You are correct that running at maximum rev will cause catastrophic failure, however, maximum RPM or Red line is not where you will find maximum horse power. The Red line on the eco-tec 2.0 is 7.6 (ECM fuel shutoff at 6.5) however Maximum Horse Power (and torque) is reached at 4,600 RPM.

A properly configured CVT will always keep an engine at maximum Hp on demand.

Key statement is "properly configured", and with my personal experience with transmissions from the Big 3 they are absolute crap. Granted I drive a Dodge Ram but I get the discount (gotta use it, be stupid not to) and I have not heard anything bad about the Hemi transmissions.

I know DCX has a CVT in the Caliber, but who else out there has a CVT in a production car?

Oh and Jump to conclusions, I reread your post and you never did say "only looking for one proxy", aparently my brain was not computing the word pair the first time I read it.
*** Edited 1/7/2007 3:30:08 AM UTC by David Sagert***

GM's transmissions are bought by Ford, BMW, DCX and Toyota. Most recent applications can be found in the Ford Edge, BMW 3-series, Upcoming DCX Hybrids and the Toyota Matrix.

Your experience probably is not with the transmissions as much as it is the programming controlling them.

Nissan put a CVT in their Altima and it's very nice. But CVT (any CVT) has a higher failure rate due to more moving parts (TTD Anyone?). The next big thing is DSG or Direct Shift Gear boxes. Audi should have the first application very soon.

There is no 'hemi' transmission. ;-P

The transmission that is mated to the hemi.

I don't like CVT's at all. I think of them as a crappy variable transmissions. Unfortunetly, manufactures are too caught up in research in CVT's to consider DSG's.

DSG's get my vote for two reasons: User controlled shifting, and extremely short shift dwell time. (I've heard numbers under 1/100th of a second)

My prefered transmission is of course a manual.