brakes

["McDowell's" <gmcd@domain.elided>]

------------------------------
Dustin
     You say "disc brakes can be designed to give more breaking power"
the truth is that drums are much more powerfull. Have you ever seen a
big truck w/discs?
Drum's have more power due to the rotating of the drum forcing the pad
into it.
I think this is called "servo action" It also depends if the drums are a
leading/trailing or a
leading/leading design. I dont think I can adaquatly explan the
diffrence without pitchures.
    I think that Ford has oversiplified the enginnering of brake systems
in your pulication
because they think us common folk wouldnt understand it.
    If your publications dosent include dozens of graphs. show various
relationships, than
It is not telling you the whole picture.
    Grant

Date: Sat, 20 Mar 1999 00:37:52 -0800
From: "W. Dustin Laur" <wdlaur@domain.elided>
Subject: Re: Brake stuff

You Made me dig out my good old Ford training books.  It has the whole
thing in the first one I opened.  The section: Braking and vehicle
weight.

The weight of a vehicle is unevenly distributed from front to rear. The
actual distribution varies from model to model, but in general, it is
distributed for-
ward of center so as to give the vehicle good handling
and road-holding characteristics. (Light trucks, of
course, have more than 70% of their weight forward of
center when unloaded.) In addition, during braking as
much as 70% of the vehicle weight may be transferred
forward.

For these reasons more braking force must be applied to the front wheels

than to the rear. (If under hard-
braking conditions, the brakes were applied equally to
the front and rear, the rear wheels might lock up pre-
maturely, causing skidding.)
Several methods of proportioning front and rear brak-
ing are used on Ford Motor Company vehicles. The first
of these is the use of disc brakes on the front and drum
brakes on the rear: since disc brakes can be designed to
provide greater braking force than drum brakes, the
braking force applied to the front wheels can thereby be
increased.

A second way of achieving this is through the use of proportioning and
metering valves. These valves are
shown in Figure 12. Proportioning valves work as fol-
lows.
Hydraulic pressure from the master cylinder is supplied
to the brakes via a set of valves which proportions the
pressure to the rear wheels.

As hydraulic pressure passes a set point, the propor-
tioning valve reduces the pressure-to the rear brakes,
creating a balanced braking condition between the
front and rear wheels.

On vehicles equipped with front disc and rear drum
brakes, there may be a metering valve. The metering
valve limits the hydraulic pressure applied to the front
disc brakes, until the rear brakes have been applied.
We will discuss the brake valves in more detail, in the
section entitled "Brake Valve Operation."

sorry for the formating I just scanned it in.  Remember if Henry siad
it,
it must be true.

Dustin
66 scout 800
and more 'other' brand X things