| Re: [GMCnet] Six wheel disks? [message #329002 is a reply to message #328999] |
Fri, 09 February 2018 21:43   |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma:
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Senior Member |
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I've always had serious qualms about any hydraulic-based parking brake
system because of the dramatic effect even a small fluid leak can have.
Dave's spring loaded system will probably overcome some of that problem.
But I think my system may be even better:
Several years ago, when the EBC Yellow brake pads first became available, I
wanted to do controlled tests on them. So, I fabricated a "brake pedal
puller" to mount beneath the GMC floorboard under the brake pedal. A chain
attaches the brake pedal to a pneumatic cylinder. Using a solenoid valve
system and a large air tank, to provide regulated pressure to that cylinder
on command, we were able to get some pretty well controlled test results --
the system even fired a paint ball on the pavement where the brake lights
came one.
A few years later, I realized one day that I'd never removed the "pedal
puller". Since I'd recently acquired a tiny Thomas air compressor, capable
of 100+ psi, it occurred to me that the two of them should work together
for some good purpose. What I wound up with is a 6-wheel (or 10-wheel if
towing) parking brake system. A dash switch activates the compressor to
produce 100 psi, pressure switch regulated. That 100 psi results in 140
lbf of brake pedal force. The compressor will maintain that pressure until
the engine battery runs dead -- a LONG time since, even with minor leakage,
the compressor runs for maybe 2 seconds out of every minute. Granted, a
hydraulic leak will also cause brake failure -- but only after it's leaked
the pedal all the way to the floor (in both the front and rear brake
systems). To release the brake, the dash switch is turned off, removing
power to the compressor, and to the normally-open solenoid valve which
dumps the trapped pressure.
It's really quite simple system and is very effective -- even without
vacuum boost, that 140 lbf on the brake pedal is darned effective with the
coach already stopped. It will even give a pretty dramatic stop with the
engine running. :-)
Just another idea to consider -- even if not a "legal" one for satisfaction
of DOT rules.
Ken H.
> On Feb 9, 2018, at 7:34 PM, Gary Kosier wrote:
>>
>> And if there is any kind of leak in the hydraulic system????
>>
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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