----- Original Message -----
From: "Vittorio Argento" <vargento@lcnet.it>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Sunday, August 12, 2001 2:17 PM
Subject: [MV] R: [MV] Alcohols/brake fluid
> From Italy. Richard, can you please re-post the AP press release?
> Thanks
>
Certainly, here it is:
AP Lockheed neither markets such fluids nor recommends their use with our
own or any other braking system.
Virtually all the problems relate to:
Long/spongy pedal
Sudden loss of brakes
They reflect certain properties of silicone fluids identified by us over
many years and recently ratified in SAE publications, namely;
High ambient viscosity
High air absorption
High compressibility
Low lubricity
Immiscibility with water
Research has shown that the relationships between problems reported and
properties identified may be expressed as follows:
Long/spongy pedal
a) Compressibility up to three times that of glycol based fluids
b) High viscosity up to twice that of glycol based fluids, leading to slow
rates of fill and retention of free air entrapped during filling and hence
bleeding difficulties.
Sudden loss of brakes:
a) Air absorption. Gasification of absorbed air at relatively low
temperatures produces vapour lock effect.
b) Immiscibility (failure to mix) with water. Whilst the presence of
dissolved water will reduce the boiling point of glycol based fluids, any
free air entrapped in silicone filled systems will boil and produce vapour
lock at much lower temperatures (100 deg C/212 deg F or thereabouts).
Hanging on of brakes:
a) Low lubricity. In disc brake systems the sole mechanism for
normalisation of system pressure upon release of pedal pressure is a
designed-in tendency of seals to recover to their "at rest" attitude. Low
lubricity works against this tendency.
b) High viscosity, exacerbating the effect of (a) above.
It should not be assumed therefore that the high price of silicone fluids
implies higher performance in hard driving or even normal road use.
AP Lockheed glycol based fluids do not contain the adverse properties
described above. The recently introduced Supreme DOT 5.1 which exceeds the
performance criteria of DOT 5, is suitable for all conditions likely to be
encountered in modern driving conditions.
End quote.
This archive was generated by hypermail 2b29 : Sun Sep 02 2001 - 11:15:38 PDT