Re: ABS questions (and NOT about when to use it!)

[Pablo Carselle <pcarselle@worldnet.att.net>]

Second Transmissio:

Pablo Carselle wrote:
> 
> Jeffrey J. Goggin wrote:
> >
> > The recent thread about ABS got me thinking about exactly how it works ... I
> > know it senses the individual wheels' rotational speeds by counting theJeff:
ABS measures independently the deceleration rate of any wheel. (as you described)That 
is, given a rotational speed of all four wheels, (as measured by the time periods 
between teeth in the wheel sensors)any excessive deceleration rate ( pulse rate from the 
wheel sensor decreasing rapidly)of any one wheel is used to anticipate a wheel lock. The 
ABS control unit (through solenoid actuated valves) prevents any additional fluid 
pressure from reaching the decelerating wheel, if the deceleration continues, the 
control unit (through the solenoid valves) opens a passage for that wheel to 
return fluid via the ABS pump back to the system. 
Therefore it is very important that a wheel sensor does not loose a teeth pulse from a
wheel at a given speed set, because...the system says...we are decelerating wheel xxx  
too quickly ( the missed tooth represents twice the time period...or half the speed ), 
therefore....  back goes the hydraulic juice...
I don't know if  I've confused you more
Regards
Pablo