They certainly test it in this state as an alternate way to bring the
moving car to a halt.
I have slid the rear wheels on my '03 OBW by cranking up on the hand
brake. it's a 4EAT
FWIW

Carl
1 Lucky Texan


Dave Null Sr. wrote:

--
to reply, change ( .not) to ( .net)

Eric Davis wrote:
Good information. It's good that they went to a system like that - I
now drive a Chrylser with that same setup. The old way of having a
sloppy cable pull the service brakes to effect parking brake caused too
much interaction with proper parking brake adjustment and proper service
brake operation. I'm glad the industry finally wised up in that area.

And you're very correct: The fact that the dedicated parking brake shoes
are designed only for that purpose now means that those shoes do not
have much safety factor in them for stopping a moving vehicle (i.e.,
each incident of abuse will eat up a good portion of their design
life). With the way the mfgrs. trim everything to bare bones for weight
and cost these days, if the engineers determine that 3mm friction
material thickness will get the car thru worst-case normal vehicle life,
they might design them for 3.5mm to hopefully give a decent bell curve.

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")


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If you pull up slightly on the hand brake while
coasting, you will hear the center diff uncouple
on AT equipped cars. My H6 makes a definite
"clunk" sound when it uncouples.

It is not a good idea to use the handbrake to lock the rear brakes on 4wd
cars with viscous center (or other limited) center diffs.

When you try, the center diff actually fights against you and puts more
torque on the rear wheels to try and keep them turning. This maybe what you
are sensing, certainly could in my EVO.
They don't recommend towing a car with this type of center diff with one
set of wheels off the ground as it will try to turn the suspended set of
wheels and if you lock them, overheat and damage the diff. Not sure if
occasionally trying to lock the rears would actually cause damage though.
The rally cars have a center diff that automatically disengages when the
handbrake is pulled.


"Bill Putney" <peva (AT) kinez (DOT) net> wrote

On Sat, 26 Jul 2003 17:49:42 -0400, TM <tm (AT) dontspam (DOT) me> wrote:

Are you sure that was the design goal rather than the effect of moving
from drum to disk brakes? One of the two shoes in a standard drum
brake system will naturally "jam" against the drum when the "free" end
is pressed against the inside of a rotating drum. Disk brakes have not
such mechanical feedback system, which is why power brakes are almost
always used with disk brake systems. An emergency or parking brake
based on disk brakes will therefore naturally have far less stopping
power than an emergency or parking brake system based on drum brakes.

--
Vic Roberts

With mechanical leverages you could perfectly achieve the forces that
would allow the wheels to lock. The problem is that the rear end of the
car would come loose and could sway from the travel direction when
driving on paved roads with a slant, same thing that happens when using
the hand brake on dirt or slippery roads with a slant.

If I am not mistaken, the hand/emergency brake on the 93 Legacy is a
drum brake system.

The requirements for parking/emergency brakes in passenger cars, are
that they should be able to keep the car still when the car is fully
loaded on a 16% incline. (Source: Bosch Automotive Technology Handbook)

I still remember the times when hand brakes were tested by making sure
that you would leave tire marks when applying them while the vehicle was
in motion and hand brakes that were applied to the rear axle propeller
shaft, which on inclines on loose roads, they would allow one wheel to
roll down hill while the other one would roll backwards (due to the
differential), with the end result that the vehicle would roll down hill.

In cargo vehicles, the emergency brake system is different from the
parking brake system. Emergency brake systems have to allow the gradual
application of the braking force, while parking brakes do not need to
meet this requirement.

In passenger cars, the parking brake allows for both functions.


Victor Roberts wrote: