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| Re: [GMCnet] Azure Vacuum Pump Install [message #293817 is a reply to message #293815] |
Wed, 13 January 2016 23:23   |
powwerjon
Messages: 849
Registered: March 2013
Karma: -2
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Senior Member |
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Bob,
This is a very good switch to use with your Azure vacuum pump or any vacuum pump and is the one that I use. I would suggest that you set it for 18”Hg as a good starting point. I assume that your using one of Dave Lenzi’s upgraded boosters? If not your really missing out on very good unit. He run’s his set point at 20”Hg. Since this past summer when I went with the same brake setup that Dave uses on his coach I have had the best brakes ever in my last 18 years as a GMC’er. The pressure switch needs to read the booster pressure and not the vacuum line pressure. Dave makes an adapter that that allows the pressure switch sense the booster pressure. Notice the silver colored adapter under the check valve on the hose from the vacuum pump. Give you accurate sensing of the booster vacuum pressure and not the hose pressure. This version gives gives you 2 sense points, one for the pressure switch and one for a line, not yet put in to a vacuum gauge on the dash for brake vacuum pressure.
http://www.gmcmhphotos.com/photos/general-pictures/p59296-dl-brake-layout.html
Other pictures of my installation.
http://www.gmcmhphotos.com/photos/general-pictures/p59297-dl-brake-layout.html
http://www.gmcmhphotos.com/photos/general-pictures/p59295-dl-brake-layout.html
http://www.gmcmhphotos.com/photos/general-pictures/p59294-dl-brake-layout.html
For those of you that have not yet seen Dave’s brake demo, it is very enlightening. His discussion on how the master cylinders really work and the different between the stock and the P-30 is very interesting and I have run both.
J.R. Wright
GMC GreatLaker
GMCGL Tech Editor
GMC Eastern States
GMCMI
78 Buskirk 30' Stretch
1975 Avion (Under Reconstruction)
Michigan
> On Jan 13, 2016, at 8:59 PM, Bob Heller wrote:
>
> I've been using this vacuum switch on my brake vacuum pump. $25 from an Ebay seller, $42 on Amazon.
>
> http://www.ebay.com/itm/Adjustable-Universal-Vacuum-switch-6-24-inHG-lockup-700r4-2004r-350c-superior-/331667328971?hash=item4d38e9cfcb:g:pmQAAOSw0HVW CYbn&vxp=mtr
>
> or search Ebay for "Adjustable Universal Vacuum switch".
> --
> Bob Heller
> 1974 X-Canyonlands 26ft
> Original 455 exc for timing chain,
> Rockwell intake, valve covers. 136k miles.
> Winter Springs FL
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| Re: Azure Vacuum Pump Install [message #293826 is a reply to message #293792] |
Thu, 14 January 2016 08:32 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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I bagged the pump out of a late 80s GM product (Pontiac I think) which has a built in switch and check valve. I'm in the process of plumbing it into the brake system, I'll put up some pictures when it's done. I ran out of brakes on a hill headed to Bean Station a couple of years ago when it vaporlocked from the heat of five miles up the mountain, and I can close to stuffing it into the guard rail backwards. This setup should preclude that in the future.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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| Re: [GMCnet] Azure Vacuum Pump Install [message #293848 is a reply to message #293817] |
Thu, 14 January 2016 14:43 |
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USAussie
Messages: 15912
Registered: July 2007
Location: Sydney, Australia
Karma: 6
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Senior Member |
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G'day,
Thought I would chime in on this and provide a bit of added information. First of all Dave's booster are MAGIC! However, I'm going
to disagree slightly with JR. The pressure switch does not HAVE to read internal booster pressure; it can be connected between the
vacuum pump and booster. HOWEVER, doing so will cause the vacuum pump to run more than if it is connected to internal booster
pressure with Dave's adapter. Why you ask? Because the check valves in ANY vacuum pump are not 100% leak tight, the volume of
"vacuum" in the line from the vacuum pump to the booster is small ambient pressure leaks past the vacuum pump check valves and into
that line causing the pressure to go above the switch set point and the pump to come on to pump it back down. When the switch is
connected to internal booster pressure the volume is MUCH greater and it takes longer for the pressure in the booster to rise above
the switch set point PLUS the ambient pressure has to leak past the vacuum pump check valve AND the check valve in the booster.
Regards,
Rob M.
The Pedantic Mechanic
-----Original Message-----
From: Gmclist [mailto:gmclist-bounces@list.gmcnet.org] On Behalf Of John Wright
Sent: Thursday, January 14, 2016 4:24 PM
To: gmclist@list.gmcnet.org
Subject: Re: [GMCnet] Azure Vacuum Pump Install
Bob,
This is a very good switch to use with your Azure vacuum pump or any vacuum pump and is the one that I use. I would suggest that
you set it for 18"Hg as a good starting point. I assume that your using one of Dave Lenzi's upgraded boosters? If not your really
missing out on very good unit. He run's his set point at 20"Hg. Since this past summer when I went with the same brake setup that
Dave uses on his coach I have had the best brakes ever in my last 18 years as a GMC'er. The pressure switch needs to read the
booster pressure and not the vacuum line pressure. Dave makes an adapter that that allows the pressure switch sense the booster
pressure. Notice the silver colored adapter under the check valve on the hose from the vacuum pump. Give you accurate sensing of
the booster vacuum pressure and not the hose pressure. This version gives gives you 2 sense points, one for the pressure switch and
one for a line, not yet put in to a vacuum gauge on the dash for brake vacuum pressure.
http://www.gmcmhphotos.com/photos/general-pictures/p59296-dl-brake-layout.html
Other pictures of my installation.
http://www.gmcmhphotos.com/photos/general-pictures/p59297-dl-brake-layout.html
http://www.gmcmhphotos.com/photos/general-pictures/p59295-dl-brake-layout.html
http://www.gmcmhphotos.com/photos/general-pictures/p59294-dl-brake-layout.html
For those of you that have not yet seen Dave's brake demo, it is very enlightening. His discussion on how the master cylinders
really work and the different between the stock and the P-30 is very interesting and I have run both.
J.R. Wright
GMC GreatLaker
GMCGL Tech Editor
GMC Eastern States
GMCMI
78 Buskirk 30' Stretch
1975 Avion (Under Reconstruction)
Michigan
> On Jan 13, 2016, at 8:59 PM, Bob Heller wrote:
>
> I've been using this vacuum switch on my brake vacuum pump. $25 from an Ebay seller, $42 on Amazon.
>
>
http://www.ebay.com/itm/Adjustable-Universal-Vacuum-switch-6-24-inHG-lockup-700r4-2004r-350c-superior-/331667328971?hash=item4d38e9c
fcb:g:pmQAAOSw0HVWCYbn&vxp=mtr
>
> or search Ebay for "Adjustable Universal Vacuum switch".
> --
> Bob Heller
> 1974 X-Canyonlands 26ft
> Original 455 exc for timing chain,
> Rockwell intake, valve covers. 136k miles.
> Winter Springs FL
_______________________________________________
GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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GMCnet mailing list
Unsubscribe or Change List Options:
http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
Regards,
Rob M. (USAussie)
The Pedantic Mechanic
Sydney, Australia
'75 Avion - AUS - The Blue Streak TZE365V100428
'75 Avion - USA - Double Trouble TZE365V100426
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| Re: [GMCnet] Azure Vacuum Pump Install [message #293849 is a reply to message #293841] |
Thu, 14 January 2016 17:47 |
Jp Benson
Messages: 649
Registered: October 2011
Location: Fla
Karma: 2
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Senior Member |
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USAussie wrote on Thu, 14 January 2016 14:31G'day,
I noted that this switch is rated for: 1/2A 125 VDC and 1/4A 250 VDC. Being that I am electrically challenged could someone please
advise what the amperage rating be for 12 VDC?
The rule of thumb is.
Divide the DC (or AC) voltage by X then multiply the amperage rating by that same value.
Effectively you're switching the same wattage.
So .5A @ 125VDC would be 5A @ 12.5VDC
JP
[Updated on: Thu, 14 January 2016 18:12] Report message to a moderator |
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| Re: [GMCnet] Azure Vacuum Pump Install [message #293874 is a reply to message #293841] |
Fri, 15 January 2016 02:36 |
appie
Messages: 902
Registered: April 2013
Location: denmark
Karma: 2
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Senior Member |
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Mornng Rob
It says maximum A and max V. If you use it with 12 V it is still max the same A
Regards
Appie
eleganza 76 "Olga" now sadly sold
6 wheel discbrake
Quadrabags
Springfield stage 2 462 olds
Manny tranny
( pictures at http://www.gmcmhphotos.com/photos/g6489-olga.html
Fulltiming in Europe july 2014 til july 2016
Denmark
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| Re: [GMCnet] Azure Vacuum Pump Install [message #293909 is a reply to message #293899] |
Fri, 15 January 2016 16:32 |
Emery Stora
Messages: 959
Registered: January 2011
Karma: 4
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Senior Member |
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It is commonly felt that you can multiply the AC amp rating by 1.8. A switch that has a 10-amp rating at 125 volts AC would be rated at 18 amps at 12 volts DC. Use a 20-amp fuse or circuit breaker to allow for voltage surge. A good rule to remember is "when voltage goes down, amperage goes up.”
HOWEVER
AC and DC switch contacts are supposed to be manufactured with different materials in order to withstand the arcing that occurs, and the resulting degradation of the switch contacts. AC circuits typically break cooler than DC circuits because the current drops to zero 120 times per second, which means arcing stops at least by the time the current goes to zero. Current in a DC circuit does not drop to zero immediately when the contacts open when there is an inductive component in the circuit. In a DC circuit, the voltage will spike when the contacts open and the arcing will be significantly more than in the comparable AC circuit. This results in more rapid contact degradation through pitting from the high temperature arc. The voltage rating only talks about insulation factor. Current rating only talks about current capacity, neither of which is related to the other. So an AC switch is NOT equal to a DC switch. If a switch is rated only as AC use caution in trying to apply that rating to DC.
P=I E or P= I * I * R only applies to a DC circuit. It will be approximately the same for a purely resistive AC circuit. Otherwise the formula for an AC circuit with an inductive load would be
P avg = V* I * cos ø where ø is the phase angle between the current and the voltage and where V and I are understood to be the effective or rms values of the voltage and current.
The term cos ø is the “power factor” for the circuit.
In addition to my Chemical Engineering courses I was required to have some EE, ME and Nuclear Engineering courses when I graduated from the Univ. of Michigan way back in 1964.
I never did get to use much of the EE I learned but it is sometimes fun to think back and to show off a little of what I learned.
The information regarding AC circuits will be of little use to owners of a GMC but once in a while it might apply.
Emery Stora
77 Kingsley
Frederick, CO
> On Jan 15, 2016, at 1:57 PM, Robert Mueller wrote:
>
> Appie,
>
> THANKS!
>
> Regards,
> Rob M.
> The Pedantic Mechanic
>
> -----Original Message-----
> From: lenze middelberg
>
> Mornng Rob
>
> It says maximum A and max V. If you use it with 12 V it is still max the same A
>
> Regards
> Appie
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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| Re: Azure Vacuum Pump Install [message #293914 is a reply to message #293792] |
Fri, 15 January 2016 17:02 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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If you'll tell me AC doesn't arc as badly as DC, I'll buy it  The local utilities still use fans on their recloser contacts to blow out the ac though. Fun to watch.
--johnny
Foolish Carriage, 76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
I forgive them all, save those who hurt the dogs. They must answer to me in hell
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