How it's Made: Auto Transmission
- Thread starter ZZman
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Good site, I've always been amazed at how these things actually work. Same with Torsen Differentials, etc. Smart people invented this stuff. Now, I just wonder how long my new 6-speed auto will hold up in a 4wd Escape my employer has me driving...
That's a good overview. It makes you appreciate how these things last as long as they do...and where just a few pennies saved in manufacturing can create weak spots for years.
Let's don't get started on how they designed the internal hydraulics...
Let's don't get started on how they designed the internal hydraulics...
Kestas
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My dad worked at the Ford Transmission and Axle engineering office for his whole 33 year career and developed 15 patents during that time. He said that though most motor heads know an engine inside and out, very few people know how a transmission really works. Yes, we're familiar with the clutches and gears, but who really understands the pressures, fluid circuits, and what governs the shifting?
JTK
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Originally Posted By: Kestas
..who really understands the pressures, fluid circuits, and what governs the shifting?
+1 to that. Heck, they loose me with all the different assemblies that need machining, drilling, boring, tapping.. It's mind boggling! Based on that Chevy HHR shot at the end, I guess this is a 4T45E.
Joel
..who really understands the pressures, fluid circuits, and what governs the shifting?
+1 to that. Heck, they loose me with all the different assemblies that need machining, drilling, boring, tapping.. It's mind boggling! Based on that Chevy HHR shot at the end, I guess this is a 4T45E.
Joel
Well built transmissions were the GM 400 and the Chrysler 727.
But yes, most guys know engine a LOT better than auto trannys. You can take off and work on most engine parts while it's in the car. With a trans, you have to yank it and take it completely apart to get at things. And have special tools.
So it remains a separate field.
But yes, most guys know engine a LOT better than auto trannys. You can take off and work on most engine parts while it's in the car. With a trans, you have to yank it and take it completely apart to get at things. And have special tools.
So it remains a separate field.
Auto trannies may as well be nuclear physics; I understand an equal amount about both. I'm amazed that the things actually work, much less work for years and years, and in many cases hundreds of thousands of miles without failing.
Originally Posted By: Kestas
... Yes, we're familiar with the clutches and gears, but who really understands the pressures, fluid circuits, and what governs the shifting?
variable pitch propellers work on the same principles. I had to study the heck out of that stuff to barely pass an Air Force test. I still don't quite get it.
... Yes, we're familiar with the clutches and gears, but who really understands the pressures, fluid circuits, and what governs the shifting?
variable pitch propellers work on the same principles. I had to study the heck out of that stuff to barely pass an Air Force test. I still don't quite get it.
MolaKule
Staff member
Quote:
Yes, we're familiar with the clutches and gears, but who really understands the pressures, fluid circuits, and what governs the shifting?
Think of piston clutches and band holding forces being controlled by two pressure pumps that give you different (differential) pressures. I.E., the difference in pressures determine shift points.
Valving, also controlled by differential pressures and gear selector position, control the amount of fluid pressure (Force/area) to the piston clutches and bands.
With electronic control, solenoids and other actuators simply "tweak" the valving and pressure to the actuators.
Yes, we're familiar with the clutches and gears, but who really understands the pressures, fluid circuits, and what governs the shifting?
Think of piston clutches and band holding forces being controlled by two pressure pumps that give you different (differential) pressures. I.E., the difference in pressures determine shift points.
Valving, also controlled by differential pressures and gear selector position, control the amount of fluid pressure (Force/area) to the piston clutches and bands.
With electronic control, solenoids and other actuators simply "tweak" the valving and pressure to the actuators.
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and what stinks even more is that they fail more often than do engines, so there is more of a chance that you will be taking your car apart.
All the quality is cad designed out of every possible part. It has been years since I went through apprentice training and worked on an auto trans but I am forgetting most everything but with a service manual they're not too bad. We had guys in the shop who worked on transmissions all the time and had them down pat. They are not magical.
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All the quality is cad designed out of every possible part.
Has nothing to do with CAD. It has to do with the engineer's spec's and the limits put on him by the bean counters.
All the quality is cad designed out of every possible part.
Has nothing to do with CAD. It has to do with the engineer's spec's and the limits put on him by the bean counters.
Kestas
Staff member
Lots of stamped parts used where they once used forged and cast. Robustness is designed OUT of cars nowadays.
MolaKule
Staff member
Quote:
Has nothing to do with CAD. It has to do with the engineer's spec's and the limits put on him by the bean counters.
'Zackly!
Systems engineers and mechanical engineers would build them like tanks, but the Design-To-Cost BC's reduce the reliability.
Has nothing to do with CAD. It has to do with the engineer's spec's and the limits put on him by the bean counters.
'Zackly!
Systems engineers and mechanical engineers would build them like tanks, but the Design-To-Cost BC's reduce the reliability.
This is why you see 18 wheelers getting millions of miles out of them. They were engineered to be tougher.
Originally Posted By: MolaKule
Quote:
Has nothing to do with CAD. It has to do with the engineer's spec's and the limits put on him by the bean counters.
'Zackly!
Systems engineers and mechanical engineers would build them like tanks, but the Design-To-Cost BC's reduce the reliability.
There is always a reason!!!
Quote:
Has nothing to do with CAD. It has to do with the engineer's spec's and the limits put on him by the bean counters.
'Zackly!
Systems engineers and mechanical engineers would build them like tanks, but the Design-To-Cost BC's reduce the reliability.
There is always a reason!!!
Originally Posted By: MolaKule
Quote:
Has nothing to do with CAD. It has to do with the engineer's spec's and the limits put on him by the bean counters.
'Zackly!
Systems engineers and mechanical engineers would build them like tanks, but the Design-To-Cost BC's reduce the reliability.
That's what the "Value Engineering" group does. It designs the value out of the product.
Quote:
Has nothing to do with CAD. It has to do with the engineer's spec's and the limits put on him by the bean counters.
'Zackly!
Systems engineers and mechanical engineers would build them like tanks, but the Design-To-Cost BC's reduce the reliability.
That's what the "Value Engineering" group does. It designs the value out of the product.
MolaKule
Staff member
We're kinda getting off topic, but a TC fascinates me in that it is such a mix of interesting technologies such as the physics of kinematics and fluid dynamics.
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