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Old 01-14-2016, 10:24 AM   #1
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An interesting POV on technology

Ever wonder why those of us with computerized buses need authorization from manufacturers before we can tinker with the computer's programming (particularly locked double overdrive on MD3060 trannies from Allison)? Because of copyright laws, something that needs to be fixed, as explained in this blog on Slate

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Old 01-14-2016, 03:39 PM   #2
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Yep! As they say in the Maker Movement, "If you can't open it, you don't own it."
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Old 01-14-2016, 04:33 PM   #3
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Quote:
Originally Posted by dan-fox View Post
Yep! As they say in the Maker Movement, "If you can't open it, you don't own it."
If is not under warranty, you ca do whatever you want.

all those companies that sell those chips for "performance improvements" will be out of business if that was the case.
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Old 01-14-2016, 11:05 PM   #4
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That's not quite accurate. Why do the performance chips people not get shut down? I don't know exactly, but I imagine it has something to do with their symbiotic relationship with automakers. You don't see performance chips for minivans. You see them for pickup trucks and sports cars -- the vehicles that traditionally provide the largest profit margins for automakers. It isn't hard to imagine that automakers recognize that the ability to performance-tune those vehicles helps drive sales of new vehicles to the die-hard fans, and that said fans are likely to order all the profit margins, er I mean optional equipment, on their cars. It also isn't hard to imagine there's a tolerance, likely written agreements, and possibly even mutual support between the automakers and performance vendors. Where there's permission given there's no violation of DMCA.

The chilling effect of DMCA is very real. Myself, I've been tempted to build hardware to download the calibration out of Allison transmissions to see whether I could work out how to binary-edit mine and unlock my second overdrive. One of the reasons I don't is that if I override some security feature in the process, even unknowingly, and even though I "own" the equipment outright and there's no warranty or other claim to be made to Allison, it could still be illegal under DMCA.

It shouldn't be that way.
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Old 01-15-2016, 07:18 PM   #5
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what does the second overdrive do? why would you want to tinker with it? can we make our buses get super mileage and fly uphills? no really, i completely dumb to the programming end of things inside my buses brain so i do mean it what would you do if it was legal and why?
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Old 01-15-2016, 07:56 PM   #6
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Long ago (I presume -- it's before my time!), the top gear in transmissions had a gear ratio of 1.0. Transmission gear ratio is the input speed in RPM (which is also the engine speed) divided by the output speed in RPM. So in the top gear, the engine is spinning 1.0 times the speed of the prop shaft going out to the differential. Engines grew stronger and vehicles traveled faster and eventually somebody asked "could we make the prop shaft spin FASTER than the engine?"

And so "overdrive" was born. In the medium-duty Allisons I'm aware of (MD3060 and B400) the first overdrive ratio is 0.75. In that gear the engine is spinning 0.75 times the prop shaft speed: if the prop shaft is doing 2000 RPM then the engine is doing 1500 RPM. The engine consumes less fuel and makes less noise as compared to running in the direct 1.0 ratio/gear.

Those medium-duty Allison transmissions are 6-speed boxes. The 4th gear is the 1.0 ratio, the 5th gear is the 0.75 ratio (first overdrive) and the 6th gear is 0.65 ratio (second overdrive). It's the same principle as the first overdrive: the engine can turn even slower for a given road speed. For the same 2000 RPM prop shaft speed the engine would do 1300 RPM in 6th/second overdrive.

I'm comfortable cruising my bus at 70 MPH. With the transmission in 5th gear the engine has to turn nearly 2400 RPM, which is fast for an 8.3L diesel. The rev limiter is right there, so it's the "full throttle cruise control" method.. I'd really like to have 6th gear available so on flat land I could still do 70, but drop the engine speed to a more reasonable 2100-ish RPM and hopefully boost the fuel economy.

Probably one reason why the bus was built with 6th gear disabled is that if a person wound the engine out to 2400 RPM in 6th, it'd be a road speed around 80-ish MPH. I suppose Blue Bird wasn't comfortable with the idea of their buses running that fast and decided to prevent it rather than rely on the good sense of school bus drivers everywhere.
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Old 01-15-2016, 10:56 PM   #7
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Actually, Allison's statement regarding the limiting of sixth gear relates to the speed limit of school bus tires more than anything else. Go figger'.
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Old 01-16-2016, 06:45 AM   #8
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strong work explaining. thanks. guess i will need some racing slicks and a good hacker! lol
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Old 01-18-2016, 11:29 AM   #9
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The speed limit thing is a good point. But that doesn't answer the question of why no 6th. If they were worried about speed, they could simply select the speed limiting feature in the control module, then they you would input the tire size(revolutions/mile) and the engine wouldn't be allowed to turn over X amount of rpm in Y gear.

It just doesn't make sense to me why you would go about limiting the speed by eliminating a gear.
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Old 01-18-2016, 12:37 PM   #10
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I've wondered why they might limit speed via the transmission too. I've seen (and modified) the speed limit control in the Cummins ECM on my bus; that was very accessible/easy to do with Cummins tools anybody can get. The change to add 6th gear is a much higher bar. Perhaps that's why it was done? Maybe the policy dates back to the time when these transmissions came on the scene but engines were not yet computer controlled?

It could be that the concern is something other than road speed (whether for chassis dynamics, tire rating, or other reason). Drive shaft speed maybe but it's intimately tied to road speed and easily controlled by the same means. I haven't been able to concoct any valid reason why 6th should be disabled, and thus my desire to ignore "those who know better," enable it, and enroll in the school of hard knocks to learn for myself!
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Old 01-18-2016, 02:33 PM   #11
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Fifth gear on a newer Allison is .71 overdrive. Sixth gear is .61 OD. Engine speed limiting is typically done by governing the RPM's. At 1800 RPM, the difference between .71 (59 mph in 5th gear) & .61 (68 mph in 6th gear) makes for about 9mph difference on my rig but different tire sizes and rear axle ratios will produce different results. But in any case, the OD difference will produce more speed at any given RPM number.

Does any of that make any sense?
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Old 01-18-2016, 03:13 PM   #12
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Wow, they've made the second OD even higher?! That would be pretty awesome if the engine doesn't mind making the torque to keep things moving through a 0.61 ratio.

Regarding the speed limiting: among engine ECMs that support road speed limiting, some support two levels of limit. They can have one speed limit for normal operation and a second limit for cruise control operation. Apparently the idea is to incentivize fleet drivers to choose cruise control because of its fuel economy $$ savings for the fleet operator. The truck is programmed with a higher max speed which can be reached by enabling cruise control and then pushing the "accelerate" button, but cannot be reached by mashing the accelerator pedal with cruise off. I think my Cummins ECM has this feature.. I vaguely recall setting two different limits to the same number.

Engine RPM limit is of course still present as well. I left that one alone on mine.
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Old 01-18-2016, 03:59 PM   #13
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At the end of the day, there is probably a monetary reason. On Allison's side it was probably cheaper to make on tranny vs a 5 & a 6 speed. I'd be willing to bet since there is only one tranny, Allison charges the builders a premium for sixth, which isn't needed for most municipalities. On the coach builder's end, I'd bet there was a liability insurance reason for having a hard lockout. These are designed to carry up to 80 children at a time. Nobody would want a school bus doing 75 fully loaded. All of this is pure speculation.
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Old 01-18-2016, 08:20 PM   #14
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As previously noted...it was the speed rating of typical school bus tires that Allison used as the limiting factor.
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Old 01-19-2016, 01:08 AM   #15
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It seems peculiar that Allison's concern is the tires. Allison requires the OK from the coach builder, who has no idea what tires are on an old bus. I'm not saying you're wrong, it just seems like a flawed process. I would think anyone could get sixth gear unlocked if they had a shop verify that the tires were upgraded.
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Old 01-19-2016, 09:27 AM   #16
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It was not an engineering issue..it was the liability as regards school districts and the V rating on the tires they typically use. Once they are out of service in a school district and the tires are upgraded the tranny should be able to be unlocked (re-programmed) but it is a hassle for Allison to verify so they don't do it often. Is it done? Yes, but usually by a hacker/builder...not Allison. I posted a chap's name & link here maybe a year ago who does them routinely. Can't recall it anymore but it should be buried here somewhere. He was the one who told me what Allison's position was.
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Old 01-19-2016, 01:58 PM   #17
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In many of the combinations, the engine has no ECU and is entirely mechanical. There's no easy way to prevent the engine from turning higher rpm in specific gears, thus lockout of the topmost gear.

Quote:
Originally Posted by Booyah45828 View Post
The speed limit thing is a good point. But that doesn't answer the question of why no 6th. If they were worried about speed, they could simply select the speed limiting feature in the control module, then they you would input the tire size(revolutions/mile) and the engine wouldn't be allowed to turn over X amount of rpm in Y gear.

It just doesn't make sense to me why you would go about limiting the speed by eliminating a gear.
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Old 01-20-2016, 07:09 AM   #18
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Quote:
Originally Posted by Scooternj View Post
Ever wonder why those of us with computerized buses need authorization from manufacturers before we can tinker with the computer's programming (particularly locked double overdrive on MD3060 trannies from Allison)? Because of copyright laws, something that needs to be fixed, as explained in this blog on Slate

Is it bad that I have been since I can remember...

When I was in first grade, I took apart an RC car and receiver which was and still is governed by strict fcc codes, attempted to make the car faster by pumping more batteries into it. I also, broke the law when I put way more power through the transmitter than was required because I wanted to race my car all the way to the end of the street. So my first grade self should have been fined and jailed.

It's commonplace for kids under 18 to have loads of copyright 'infringed' material. This kind of stupid crap just goes to point out how ignorant and how detached Americans are from our politics, because our politics are just a giant joke with so many things that are morally fucked that it's not even funny.. Why? Greed and money... here's one solution i have found, but I haven't looked into how effective it can be or how legitimate it is... Looking into it. Action is the only way you can change this crap... Or join the trolls, file a patent that's so similar to the company owned design, then sue them for infringement.

I have read article after article of people being sued, and even their entire lives ruined because they left their wifi open (copyrighted porn)... sued isn't the worst part. The government is trying to put innocent people in prinson (child pornography, takes a linux laptop and 5 minutes to break any wifi pass). I'd go thorugh and find you some links... but a) i have read these articles years ago, and b) I don't have the time. C) i'm not going to go to the length it takes to CYA on linking you to the programs to crack the wifi.

What I WILL do though is let you know that your sources need polished and you also need to go hunt down the sources of the information in these articles... Often times the source chain is circular Look at the click bait on that web page. That's not a realiable news outlet. I'm sorry, it's just ...

pubmed is a great source for research articles (the source) and you can find out who FUNDED THE PROJECT

arstechnica.com is a good all around reasonable outlet for news.
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