Vacuum Brake Lock

[Russell]

On the list of upgrades found for our coach "Harry", there is an item called "Vacuum Brake Lock". I assume it is some type of vacuum assisted parking
brake, but I cannot find another GMC that has one, or any information about it. Does anyone have experience with this system? I think the following
pictures show the system.

http://www.gmcmhphotos.com/photos/data/7009/medium/What_is_this.jpg

http://www.gmcmhphotos.com/photos/data/7009/medium/zoomed_in.jpg

http://www.gmcmhphotos.com/photos/data/7009/medium/Found_this_switch_cover_in_a_box_in_the_GMC.jpg

http://www.gmcmhphotos.com/photos/data/7009/medium/Vacuum_Brake_Switch.jpg

http://www.gmcmhphotos.com/photos/data/7009/medium/Auxiliary_vacuum_booster.jpg

http://www.gmcmhphotos.com/photos/data/7009/medium/side_view_auxiliary_vacuum_booster.jpg

--
Russell Keith

1978 Eleganza II

Dunedin, Florida

 

[LQQKatJon]

1st picture you have is the cruise control tranducer.(located just to passenger side of distributor). there is one item that is coming off of it,
that I am not sure I recognize. it usually has speedometer cable in, and speedometer cable out, I only see one cable.

as for the brake lock:

the clean looking etched switch plate you have(the one that says "read warnings and operating instructions") , is just like the one I have
disconnected on my coach. I do not think it is related to your "vacuum brake lock". the plate one, like on my coach, is electrical solenoid on the
rear feeding brake line. Press the brake, hit the switch, and the electric soleniod holds the rear brake pressure. You release the switch and the
solenoid should open up. I have a mechanical one on my vw dune buggy, that is similar, except I push a mechanical button right on the brake line on
that that one.

it looks to me that device by your steering shaft, would be that vacuum brake lock device. I am guessing maybe the same as the electric version,
except it used a vacuum solenoid? but that is my guess.

I personally have disconnected that brake lock on my GMC, it was old, not used, and I just could not trust it because I did not know the history of
the device. I would think you may want to do the same.

--
Jon Roche
75 palm beach
St. Cloud, MN
http://lqqkatjon.blogspot.com/

 

[Ken H.]

Make that ...(front or REAR).
... (IF there really is one) to the original MC and to one of the brake
systems (front or read).

Ken H.

 

[jim kanomata1]

I believe your getting the Hydraulic brake mixed up with cruse control
Vacuum.
Call me and I'll clarify them for you.

> On the list of upgrades found for our coach "Harry", there is an item
> called "Vacuum Brake Lock". I assume it is some type of vacuum assisted
> parking
> brake, but I cannot find another GMC that has one, or any information
> about it. Does anyone have experience with this system? I think the
> following
> pictures show the system.
>
> http://www.gmcmhphotos.com/photos/data/7009/medium/What_is_this.jpg
>
> http://www.gmcmhphotos.com/photos/data/7009/medium/zoomed_in.jpg
>
> http://www.gmcmhphotos.com/photos/data/7009/medium/Found_
> this_switch_cover_in_a_box_in_the_GMC.jpg
>
> http://www.gmcmhphotos.com/photos/data/7009/medium/Vacuum_Brake_Switch.jpg
>
> http://www.gmcmhphotos.com/photos/data/7009/medium/
> Auxiliary_vacuum_booster.jpg
>
> http://www.gmcmhphotos.com/photos/data/7009/medium/side_
> view_auxiliary_vacuum_booster.jpg
>
> --
> Russell Keith
>
> 1978 Eleganza II
>
> Dunedin, Florida
>
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--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk
http://www.appliedgmc.com
1-800-752-7502