B
Bob F
Guest
On 4/20/2023 3:56 PM, SteveW wrote:
I had a \'93 Voyager that had the Bendix 10 ABS system, which also had
such an accumulator. That was good for about 3 assisted stops, but after
that you still got some braking especially with both feet on the pedal.
After the system failed (which apparently happened to all of them
eventually), I replaced it with a vacuum brake system lines acquired
from a junkyard and a new vacuum assist master cylinder assembly.
On 20/04/2023 22:23, Carlos E.R. wrote:
On 2023-04-20 22:48, SteveW wrote:
On 20/04/2023 18:45, Carlos E.R. wrote:
On 2023-04-20 11:27, The Natural Philosopher wrote:
On 19/04/2023 20:54, Carlos E.R. wrote:
On 2023-04-19 17:45, Bob F wrote:
On 4/19/2023 5:36 AM, Carlos E.R. wrote:
On 2023-04-19 14:12, Theo wrote:
In uk.d-i-y Carlos E.R. <robin_listas@es.invalid> wrote:
Interesting.
How does it work, you foot the brake pedal, and the car
decides whether
to apply the actual brakes or generator mode?
In general yes. The car will decide whether to use regen or
friction
brakes. For example mostly regen if the battery can take it,
but at low
speeds friction might be used for the last few mph down to zero
where regen
is weak. Also in an emergency stop both might be used.
What happens when you release the accelerator pedal? Does it
just coast
along, or does it apply \"engine brake\" as in a gasoline car?
That\'s called \'one pedal driving\', and on many EVs you can
adjust the
retardation (regen) in a number of steps from coasting through
to quite
aggressive braking. Coasting is more like a regular
transmission where you
have to use the brake pedal, whereas with higher levels you can
drive with
accelerator alone.
By \"regular transmission\" you mean \"automatic\"?
Most cars here have a manual transmission, and on those the
(gasoline) car brakes somewhat when the accelerator pedal is
released. We use that to maintain the speed when going down long
slopes, instead of using the brake. If we need more brake
action, we shift to a lower gear.
Obviously, with an electric car, you would make a simple
adjustment to your driving style to accommodate the small
difference. Especially since using the brake pedal will recharge
your battery for free.
Of course, that\'s the advantage of electrics. I just wondered how
they arranged the controls.
Then the brakes must be \"by wire\", so that the car decides to
apply them or not. Makes me a bit uneasy.
Not arf as uneasy as power assisted brakes that lose power assistance.
I had a manual XJS once. The brakes were fed not by vacuum, but by
an electric pump.
I was just coasting to a halt in my drive when I switched the
engine off. The brakes vanished.
Totally?
That\'s not supposed to happen. You should only lose the assist, so
you just had to press the pedal harder. Depending, you\'d feel the
brake become \"hard\".
I remember that I would play with it. Car parked, engine stopped,
press the brake pedal and release. After two or three pushes, it
suddenly became stiff and would not yield: the vacuum storage was
spent.
I don\'t know how the assist works in my current car (an Opel Corsa).
There is no vacuum storage in sight.
My father had a couple of Citroens, with their hydraulically assisted
brakes. There was an accumulator to allow the brakes to stop the car
if the engine failed, but after a couple of presses, there was NO
noticeable braking at all. When I had to tow him, we used a rigid
bar, as he effectively had no brakes and I needed to brake for both
cars. Luckily we were only going a mile and a half to a garage.
In my case, the brakes did work, but you had to press really hard.
That\'s normal for most cars, using vacuum servos to assist the existing
brake master cylinder. Citroens are different (they seem to like to be
weird), using a hydraulic pump to power the brakes (it also powers the
power steering and the rising and falling suspension), with a small
accumulator. Once that accumulator is emptied, not only is there no
assistance, but there are no brakes at all.
I had a \'93 Voyager that had the Bendix 10 ABS system, which also had
such an accumulator. That was good for about 3 assisted stops, but after
that you still got some braking especially with both feet on the pedal.
After the system failed (which apparently happened to all of them
eventually), I replaced it with a vacuum brake system lines acquired
from a junkyard and a new vacuum assist master cylinder assembly.