Anti Blockage System (ABS) braking system : anything I'm missing?

ABS as I understand it: there are wheel sensors that tell a computer that indeed wheels are spinning and at what rate. Transmission and some engine data is also used here, too. when the brakes are applied, there should be a gradual (relatively) slowing of the output from the wheel sensor. a locked wheel does not spin or provide rate data to the brake computer. the brake computer then releases pressure to the affected wheel brake cylinder until the wheel speed matches other data. Note this would be a mechanical energy dissapation system as used on most cars today.

Now unless someone has built a system unknown to me, vacuum is generally used for a pedal effort assist system in the master cylinder of the main braking system. Remove vacuum and the brake pedal becomes too hard for many to use.

Sounds fishy since I haven't had regen braking effectively demonstrated to me in this manner/ I have issues doing the final stop portion at very low speed.

You don't need ABS if you have a plain mechanical system but ABS is nicer and much harder to implement.
Not sure how the controller would deal with wheel data

my $.02: your mileage can and will vary.

The vacuum boost or hydroboost systems on your brake system have NOTHING TO DO WITH THE ABS SYSTEM. If the brakes on the car were boosted then you should ensure they remain boosted after the conversion.

There should be no conflict between an antilock system and regenerative braking. With the exception you would want to turn the regenerative system off or waaaay down when you were in a situation where ABS might be necessary.

Ok, a stand alone ABS (Antilock Brakeing System) does exactly what it's name implies. It prevents the wheels from locking up (skidding) during braking thus allowing the maximum braking friction without loosing the the ability to steer and control the vehicle or prevents the rear wheels from locking and causing a skid. There are a couple of subtle side benifits we don't need to go into.

A functioning ABS is even of more value in a EV because of skinny LRR tires, high tire pressures and higher average vehicle weight. All of which cause a tire to skid easier.

The standard ABS systems I worked with were usually stand alone and self contained. ABS systems on vehicles that used the ABS pump and valve system for traction and stability control are a different story. (Maybe)

The standard systems work as follows.

Your normal vacuum boosted or hydroboosted brakeing sustem is ported to and through the ABS valve and pump body that is operated by the ABS control unit. With the system functioning, until a wheel locks up or has a radically different speed during braking this unit does nothing and the brake system works normally. If control system fails, the ABS unit does nothing and brakes will continue to function normally.

in a four wheel antilock system each wheel has a speed sensor and cog wheel that sends pulses to the ABS control unit.

In it's simplest form, when the control, unit sees a pulse difference from the speed sensor in one or more wheels it will release the pressure from the normal brake system to those wheels, then through a system of valves uses the antilock pump to pulse pressure to those wheel until the pulses from the wheel speed sensor again match.

There are multiple algorithms in the controller programming to handle 4 wheel lock up and many other different conditions. We don't really need to go into those.


Simply speaking, leave it alone when doing a conversion, if it requires a CAN buss or other connection to engine, traction, stability or transmission controllers it will just stop functioning and will work just like a normal non ABS system. If it works then you will find your vehicle safer.

I think I've covered the basics, but I've been away from it for a while, so any body with more information PLEASE jump in.

Hope this helps,
Jim

Thanks guys. All of your views kind of merge to a final conclusion : I got some principles mixed up :
1) I just figured out a vacuum pump is generally needed to replace what the engine used to do for the power brakes (wasn't too sure of what that was exactly) but now I realize this is what allows you to prevent needing to stand straight on your braking pedal whenever you need to brake. So no vacuum pump and you have a pedal as hard as damn brick. So my supplier is right in saying I still need one (I didn't want to insult his intelligence but I like to understand things whenever I'm told "that's how things go, don't ask" ). Mine should be vacuum-based, I'll double-check in the mechanics' guide.
2) I concur with what you said about the ABS as a security feature. I definitely want to keep it. The TIM 600 should only focus on regen and ABS comes as an emergency braking system that will prevent me from a little trip in the road sides (I can tell it is very effective in the snow )
I'll still need to check what data it computes but I would be happy if it only checked if wheels are spinning or not, whatever the speed of vehicle.

Your normal vacuum boosted or hydroboosted brakeing sustem is ported to and through the ABS valve and pump body that is operated by the ABS control unit.

Click to expand...

So to sum up : I'll always need a vacuum pump, irrespective of having ABS or not. Right?