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Topic: Air brake thingy,  (Read 660 times) previous topic - next topic

Air brake thingy,

Hi all,

Me again,
What is this thing in the front of my coach and what does it do,
Its part of the braking system and its connected by a thin rubber tube,
I dont even know what its called, So cant search for it,
It keeps blowing the hose off it,

Another question, My trip meter has stopped working on the speedo, Any ideas on how to fix it,

Thanks in advance, Brian,
Cheers, Brian,
1989 Foretravel Grand Villa, 36 foot ORED, 300 HP Catapillar and Four Speed Allison Auto,
Right Hand drive, two Mid doors, Makes a good flow thru ventilation in hot weather,
Located in Melbourne, Australia,  The Land Down Under,
Honda Blackbird, 1100XX.    2002 Gemini 105 MC Catamaran,

Re: Air brake thingy,

Reply #1 –
Brian,

The round globe looks like a vacuum reservoir.  The very thin line from the reservoir probably goes up to your air conditioner/heater control.  The air flow control doors in the dash are positioned by vacuum motors.

The other thing may be a vacuum generator?  Air pressure blows across a venturi and generates vacuum?
Do a Google search for Ford D7ht-19c747 to see discussions about this type device on other brand coaches.

I don't think either of them have anything to do with your brakes.

Can't help you on the tripmeter...

Cheers
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Air brake thingy,

Reply #2 –
Quote from: Chuck & Jeannie –
Brian,

The round globe looks like a vacuum reservoir.  The very thin line from the reservoir probably goes up to your air conditioner/heater control.  The air flow control doors in the dash are controlled by vacuum motors.

The other thing may be a vacuum generator.  Air pressure blows across a Venturi and generates vacuum??

I don't think either of them have anything to do with your brakes.

Cheers

Thank you,  It has air in it, Thats why I presumed it was some thing to do with the brakes,
I have no idea on it, But connected to the AC in the front could be it,
It dissapears into the wood work, and I dont know where it goes,
They are both connected by the tube
Cheers, Brian,
1989 Foretravel Grand Villa, 36 foot ORED, 300 HP Catapillar and Four Speed Allison Auto,
Right Hand drive, two Mid doors, Makes a good flow thru ventilation in hot weather,
Located in Melbourne, Australia,  The Land Down Under,
Honda Blackbird, 1100XX.    2002 Gemini 105 MC Catamaran,

Re: Air brake thingy,

Reply #3 –
Yes, your dash HVAC system operates by vacuum.  The round thing is the vacuum reservoir. If the air/vacuum unit is not functioning, any small 12 VDC vacuum pump can be substituted.  You will also find these 12 VDC units on many diesel powered vehicles for the same purpose, so pretty common.

Here is one: http://www.dormanproducts.com/p-30657-904-214.aspx
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Air brake thingy,

Reply #4 –

Cannot find it at the moment, but there was a recent thread discussing the vacuum amplifier.  This link is to one on Amazon so at least you know what to search for.  Dorman Vacuum Amplifier

This link is to an older thread about  installing a vacuum pump Vacuum Pump which might be relevant along with this thread

As an Amazon Associate Foretravel Owners' Forum earns from qualifying purchases.
40ft 1997 U320

Re: Air brake thingy,

Reply #5 –
Quote from: DayDreamer –
Cannot find it at the moment, but there was a recent thread discussing the vacuum amplifier.
You're probably talking about my thread where I recently went through much of the same learning curve: Dash Air Stuck on Defrost/Vacuum Pump Replacement
1987 Grand Villa ORED
2001 U320 4010

Not all that wander are lost... but I often am.

Re: Air brake thingy,

Reply #6 –
Quote from: Elliott –
You're probably talking about my thread where I recently went through much of the same learning curve: Dash Air Stuck on Defrost/Vacuum Pump Replacement

That looks like it, Thank you,
Cheers, Brian,
1989 Foretravel Grand Villa, 36 foot ORED, 300 HP Catapillar and Four Speed Allison Auto,
Right Hand drive, two Mid doors, Makes a good flow thru ventilation in hot weather,
Located in Melbourne, Australia,  The Land Down Under,
Honda Blackbird, 1100XX.    2002 Gemini 105 MC Catamaran,

Re: Air brake thingy,

Reply #7 –
Remember, if your vacuum pump is cycling a lot, your control on the dash will have a fault that allows a leak when the slider is all the way in the left position. Make a stop or remember to keep it a quarter inch to the right. If allowed to run much of the time, the vacuum pump will burn out.

Pierce
Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Air brake thingy,

Reply #8 –
If it's blowing the hose off the round vacuum generator the exhaust port is clogged, probably by bugs
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Air brake thingy,

Reply #9 –
I had an issue with the tube into the vacuum reservoir (spherical thing) falling off.  I found the end of the tube expanded and slightly cracked due the expansion.  I trimmed the end and used a tiny amount of silicone to hold it in for good.
Replacing the tube is difficult because the other end passes through the fire wall and under the dash somewhere.  Only the end seemed bad, the rest of it appeared to be good.
John Fitzgerald
1991 U300 (SAI) Side Aisle Island Bed 40'
Detroit 6V92 with Allison Retarder
Meridian (Boise), Idaho