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Throttle Controllers
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Circlotron:

--- Quote from: IDEngineer on April 08, 2021, 07:50:16 pm ---imagine a moving car where you've completely released the throttle but left the clutch engaged. The engine compression is now acting as a brake, slowing the car,

--- End quote ---
Wouldn't that braking effect instead be the pumping losses from the engine trying to draw in air against a closed throttle? Not the same as compression braking in a diesel where you may have an exhaust valve timed to release compression at the top of the stroke (and make a LOT of noise!) so that the energy used in compressing the air is not recovered on the expansion stroke. That may sound like I'm being pedantic and picking on your words, but no offence meant.  :) We engineers tell it like it is. I do understand though the idea of simplifying descriptive terms for a given audience.
NiHaoMike:

--- Quote from: IDEngineer on April 08, 2021, 07:50:16 pm ---I do not want a steering wheel position sensor driving a linear positioner to steer the front wheels... it's far less reliable than a simple shaft driving a rack-and-pinion. The latter will fail gracefully and allow me to control the car to a safe stop, but a failure of almost any component in an electronic steering system means you no longer control your vehicle. There is no graceful degradation.

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Are there any production cars that are completely drive by wire with no mechanical connection from the steering wheel? I'm under the impression that every power steering system ever used in a production car worked in parallel with the traditional rack and pinion system.
james_s:

--- Quote from: NiHaoMike on April 15, 2021, 01:19:16 am ---Are there any production cars that are completely drive by wire with no mechanical connection from the steering wheel? I'm under the impression that every power steering system ever used in a production car worked in parallel with the traditional rack and pinion system.

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I think it's currently required by law, I could be wrong but I have never seen a fully drive by wire car. It would not surprise me at all if somebody made one at some point though.
hans:
I don't know about cars.

I do know about steer-by-wire in tractors. John Deere 7R/8R have been using such systems for certainly more than 6 years now. They use a digital potentiometer with quad-level redundancy (4x PWM wires) and a single actuator to control the resistance.

Oh and you should hear the number of warnings/beeps if one of those PWM wires fail... At that point you're not allowed to engage the machine into drive anymore IIRC

They even market it as a comfort feature, as the steering sensitivity(+resistance) can change for road speeds and soil work/maneuvering speeds.
Monkeh:

--- Quote from: Circlotron on April 15, 2021, 12:45:31 am ---
--- Quote from: IDEngineer on April 08, 2021, 07:50:16 pm ---imagine a moving car where you've completely released the throttle but left the clutch engaged. The engine compression is now acting as a brake, slowing the car,

--- End quote ---
Wouldn't that braking effect instead be the pumping losses from the engine trying to draw in air against a closed throttle? Not the same as compression braking in a diesel where you may have an exhaust valve timed to release compression at the top of the stroke (and make a LOT of noise!) so that the energy used in compressing the air is not recovered on the expansion stroke. That may sound like I'm being pedantic and picking on your words, but no offence meant.  :) We engineers tell it like it is. I do understand though the idea of simplifying descriptive terms for a given audience.

--- End quote ---

You're quite correct, the intake vacuum provides the braking effect. If it were merely compression (and subsequent decompression..) you'd only be gaining braking from mechanical losses in the engine, which are small. A N/A diesel has almost no engine braking due to this.
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