quattro digest, Vol 1 #5011 - 14 msgs

[Wally Choate]

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[ Picked text/plain from multipart/alternative ]


Subject: RE: Bomb replacement further question


Bernard makes sense to me but If anyone is still not fully clear look at it=
 like this: the bomb is strictly an energy storing device (similar to an ai=
r compressor storage tank) and the braking system needs the available surge=
 of stored energy to function properly (full pressure without pump pulses).


From: "Bernard Littau"
To: ,
Subject: RE: Bomb replacement further question
Date: Fri, 6 Jun 2003 01:39:53 -0700


>
> Thanks to all who replied first off, one further question for you all. If
> i don't have to bleed to brakes after replacing this then how does the
> bomb provide assistance to the brakes, i was assuming that there was a
> brake line going to the bomb from the master cylinder/servo.
>

Hi Iain.

Are you familiar with the vacuum assist brakes found on most cars? In
those, there is a rather large round object between the firewall and the
master cylinder. This is both the vacuum reservoir and vacuum powered
linear motor that provides the boost to the pedal pressure exerted on the
master cylinder.

On the type 44 Audi, the linear motor is also between the firewall and the
master cylinder, but it is rather small. The reservoir for this motor is
the bomb, and power is provided to it by hydraulic pressure from the
hydraulic pump.

In both cases, the boost is provided mechanically to the plunger that
actuates the master cylinder, along the same shaft that the brake pedal
pushes.

Clearly, vacuum in no way communicates with the brake fluid in the vacuum
powered boost system. The hydraulic powered boost system also does not
communicate with the brake fluid.

There is a line that looks much like a brake line going into the servo
(linear motor) behind the master cylinder. This line, however, carries
Pentosin hydraulic fluid, not brake fluid.

Make sense?

Best,

Bernard Littau
Woodinville, WA
'88 5ktq



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