4 ms·

This will help reduce engine noise, as well as stink and heat from the truck's exhaust, both of which will be nice. Buses are also loud in city streets and both

by ssharp 10y ago

This will help reduce engine noise, as well as stink and heat from the truck's exhaust, both of which will be nice. Buses are also loud in city streets and both trucks and buses use braking systems that are fairly loud. I don't know what braking systems these will use but I'm guessing it still needs to be pretty heavy duty and could still be loud.

masklinn 10y ago
> I don't know what braking systems these will use Er… regenerative? Short of emergency braking which should almost never be necessary in city traffic.
- sp332 10y ago
  Regenerative brakes typically can't handle hard braking braking. In Teslas for example it's paired with regular disc brakes, but those brakes are rated for 100,000 miles because of the reduced wear. I would expect this truck to have regular (loud) air brakes installed, but they might be used less often if the driver brakes early & gently enough for regen to do the whole job.
  - masklinn 10y ago
    > Regenerative brakes typically can't handle hard braking braking. Which I very specifically noted…
    - sp332 10y ago
      But if you're driving a 20-ton truck, even routine braking will probably be "hard" braking.
      - function_seven 10y ago
        Presumably if the motors are beefy enough to accelerate that 20-ton truck, they're beefy-enough to regeneratively brake it as well, right? I mean, still not as quickly as friction brakes can, but at a comparable level to passenger car regenerative braking.
  - Animats 10y ago
    Regenerative brakes can handle hard braking, but you need some place to dump the energy. Locomotives use big resistive iron grids and fans for this. Those are in the "ears" seen on the sides of modern Diesel-electric locomotives. Electric cars usually don't have that. A heavy truck, though, probably should. Dynamic braking is great for going down long grades, because the motors and resistors can handle the load continuously without overheating. Some power can go back into the battery, but the battery may not be able to take it all, due to charging rate limitations.
ethbro 10y ago
For context, the unique sound of heavy truck braking is when they use their engine to save pads. There are places where engine compression braking is specifically prohibited due to noise concerns. See https://en.m.wikipedia.org/wiki/Compression_release_engine_brake https://en.m.wikipedia.org/wiki/Compression_release_engine_b... (also called Jake brake by truckers)
- nawitus 10y ago
  Had to Google it, since I've never heard it in Europe: https://www.youtube.com/watch?v=wPRLOyWKxmk https://www.youtube.com/watch?v=wPRLOyWKxmk
- ssharp 10y ago
  I'm not sure if engine brakes cause the city braking noise though. I tend to notice more of the air brake sounds when the air pressure get released.

by ssharp 10y ago

masklinn 10y ago

> I don't know what braking systems these will use Er… regenerative? Short of emergency braking which should almost never be necessary in city traffic.

sp332 10y ago
Regenerative brakes typically can't handle hard braking braking. In Teslas for example it's paired with regular disc brakes, but those brakes are rated for 100,000 miles because of the reduced wear. I would expect this truck to have regular (loud) air brakes installed, but they might be used less often if the driver brakes early & gently enough for regen to do the whole job.
- masklinn 10y ago
  > Regenerative brakes typically can't handle hard braking braking. Which I very specifically noted…
  - sp332 10y ago
    But if you're driving a 20-ton truck, even routine braking will probably be "hard" braking.
    - function_seven 10y ago
      Presumably if the motors are beefy enough to accelerate that 20-ton truck, they're beefy-enough to regeneratively brake it as well, right? I mean, still not as quickly as friction brakes can, but at a comparable level to passenger car regenerative braking.
- Animats 10y ago
  Regenerative brakes can handle hard braking, but you need some place to dump the energy. Locomotives use big resistive iron grids and fans for this. Those are in the "ears" seen on the sides of modern Diesel-electric locomotives. Electric cars usually don't have that. A heavy truck, though, probably should. Dynamic braking is great for going down long grades, because the motors and resistors can handle the load continuously without overheating. Some power can go back into the battery, but the battery may not be able to take it all, due to charging rate limitations.

ethbro 10y ago

For context, the unique sound of heavy truck braking is when they use their engine to save pads. There are places where engine compression braking is specifically prohibited due to noise concerns. See https://en.m.wikipedia.org/wiki/Compression_release_engine_brake https://en.m.wikipedia.org/wiki/Compression_release_engine_b... (also called Jake brake by truckers)

nawitus 10y ago
Had to Google it, since I've never heard it in Europe: https://www.youtube.com/watch?v=wPRLOyWKxmk https://www.youtube.com/watch?v=wPRLOyWKxmk
ssharp 10y ago
I'm not sure if engine brakes cause the city braking noise though. I tend to notice more of the air brake sounds when the air pressure get released.