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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: Aug 2009 Posts: 311 'Bolter | | 'Bolter Joined: Aug 2009 Posts: 311 | My '34 has this hydrovac unit , which has a garden hose connecting it to this unit , different view. The mounting looks pretty factory. But I have not read of a hydrovac in the factory manual so I am thinking it was added? The brakes are stock mechanical, can this system work? My other 1.5 ton does not have a hydrovac, so I have read about them, but not worked with them. Any and all help is appreciated! | | | | | Joined: Feb 2002 Posts: 12,029 Cruising in the Passing Lane | | Cruising in the Passing Lane Joined: Feb 2002 Posts: 12,029 | bracket off a bracket, double nutted, farmer fix, no telling how it evolved, I could see someone thinking they could improve braking/ reduce foot power required of mechanical brakes, by rigging something up, but with mechanical brakes there isn't any 'hydraulics' to vac  hydraulics didn't happen until about 36 - if you think you can make it work [safely] it could be an interesting historical feature, but I wouldn't call it a 'hydrovac', because it's nothing like one Bill | | | | | Joined: Feb 2004 Posts: 29,821 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,821 | That's a vacuum-assist unit used to help out the mechanical brakes, similar to the ones on my grandfather's 34 Chevy flatbed trucks when they were hauling bottled beer from Milwaukee to Nashville Tennessee in the late 1930's. Later, they added an insulated trailer behind one of their rigs to haul ice-chilled keg beer. No brakes at all on the trailer!
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Aug 2009 Posts: 311 'Bolter | | 'Bolter Joined: Aug 2009 Posts: 311 | Thanks HotRod, I am assuming they were an afterrmarket item? Or were they offered by the factory or dealer? Anybody have a line on someone who rebuilds them? | | | | | Joined: Feb 2004 Posts: 29,821 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,821 | I never saw the family rigs, just heard about them. It's probably an aftermarket accessory, and rebuilding will probably involve fabricating home-brewed seals. I'd suggest making an aluminum piston that's a close fit to the cylinder bore and grooving it for 2 or 3 big O rings. Valving the vacuum to the cylinder can probably be done with air brake components of some sort. Be sure to include a vacuum reservoir tank somewhere in the system to get at least one power-assisted brake application after the engine stalls.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Aug 2009 Posts: 311 'Bolter | | 'Bolter Joined: Aug 2009 Posts: 311 | Well Jerry was correct my unit is a Bragg Kliesrath vacuum brake system, that was used on Stutz, Duesenberg, Packard, Lincoln and others. I have read that it produces 200-280lbs of vacuum pressure. So far the only place I have found that has parts available is Classic & Exotic service Inc. Apperantly Bragg Kliesrath published a a book "Safety demands the power to stop" 1920. If anyone has this, or any other information please let me know. | | |
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