RE: (ET) Bye bye brakes

["Pieter Litchfield" <plitch attglobal net>]

I have recently replaced the transzxle (and  rebuilt the original brake) on
my e-15.  Apparently there were at least two different designs - one in
which the caliper was fixed but the rotor floated (was free to slide a bit
on the transmission shaft) and another where the caliper floated on pins 
but
the rotor was fixed.  Somehow I managed to combine the two designs so that
both parts are now floating on mine.  It seems to work as well as can be
expected of two square inches of mechanical disk brake!  In addition, I use
a bit of "Never-Seize" graphite/lithum grease to lightly coat all the
floating points, since as I am sure we ALL have experienced, the brake 
rotor
dearly loves to weld itself to the shaft.  Lubing and checking for free
float should be an annual rite.  In addition the brake power cut off switch
on the linkage needs to be adjusted so that the motor is not working 
against
a fully applied brake, causing wear and ineffective braking.  I allow for a
bit of overlap - the brake just begins to take effect when the power switch
kills motor current.  It is, in my opinion, a design which when working 
well
is of marginal capacity, and which almost never works "to spec"!  Bill's
upgrade is surely worth it.  I suspect that the design was an original part
from the transaxle supplier (Peerless) and is designed to be used on 
lighter
gas engine machines.  Nobody envisioned six big batteries headed down a
steep slope.  If the throttle is not cut, or if you don't bounce a activate
the seat cut-off switch, the tractor is capable of some effective
regenerative braking effort.  If however (as I have done) a bump causes a
power cutoff in the middle of a hill, the mechanical brake may be barely
adequate to save you!  I always shift to a lower speed range (using the
mecahnical transmission) for steep downslopes, and then keep my foot off 
the
brake pedal so I maintain power.  Of course, we are talking about a brake 
on
the input shaft of a differential, so braking is limited by the available
traction at either rear wheel.  If one rear wheel is unweighted (as when
traversing across a slope), the available braking traction is limited to 
the
amount of force that can cause the lighter rear wheel to slide - sometimes
not much.  All in all, the E series brake is a weak point!  If equipped 
with
two drum or disk brakes at the rear wheels, the brakes would have been far
more effective, and of course more expensive.  But you could have employed
brake steeering and traction control as well as do "real" tractors.  This
would appeal to me because even with a weight box on the back and chains, I
often spin rear wheels with a full bucket on the front mounted loader.
Being able to independently brake each rear wheel would be a big advantage
for me in trasferring power when one has better traction than the other.
Hmmmm...... winter project?

I used to have an old Jacobson tractor that had a transmission brake on the
input shaft like the GE, but it was a very simple "outside drum" where the
pedal linkage pulled tight a lined metal band looped around a drum attached
to the shaft.  It was very effective, but of course suffered from the same
limits on brake force generated by sliding a wheel.



-----Original Message-----
From: owner-elec-trak cosmos phy tufts edu
[mailto:owner-elec-trak cosmos phy tufts edu]On Behalf Of Jim (fiskfarm)
Sent: Monday, February 04, 2002 9:43 AM
To: Christopher Zach
Cc: Elec-trak
Subject: Re: (ET) Bye bye brakes


Hey Chris,

The rotor is NOT supposed to "deform" but rather float free on it's keyed
shaft. I use a combo of air chisel, Breakaway and sometimes heat to free up
the
rotor and then remove it , clean up both shaft and sleeve, retighten the
rivets
by hammer and anvil (or replacement) and reinstall all with a gentle 
coating
(you don't want any on the rotor and pads) of Never Seize. Here, unlike a
car,
the caliper doesn't float, but the rotor does. Also you will want to sand
the
rotor smooth with either a power sander or rotate the rotor in place with
the
motor while sanding by holding the paper against it. Not for the faint of
heart
but probably the fastest for the more experienced. DO NOT "grab" the rotor
with
the paper , but rather sand one side at a time. New pads (if they are shot)
go
without saying. Stainless steel rotors would avoid about 99% of the 
problems
with these breaks. That and Never Seize.

Hope this helps you along,

Jim

Christopher Zach wrote:

> Well, I figured out why I have no brakes....
>
> No brake pad :-)
>
> Seriously, the outboard pad is gone. It appears that the brake lever
engages
> a cam which pushes on a metal dowel which pushes on a pad which pushes 
> the
> disc into another static pad on the other side. Interesting design, are
> there any specs for pad clearance on the static pad (if it wears down, 
> the
> disc will have to deform more and more for the brake to engage, thus
> reducing brake effectiveness)
>
> Ah well, it looks like the pad disintegrated or something. I'll call Mr.
> Gunn and see if he has a new puck.
>
> Chris