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Old 06-30-2019, 06:50 PM   #1
Skoolie
 
Join Date: Oct 2018
Location: Georgia
Posts: 169
Year: 2002
Coachwork: Bluebird
Chassis: Tc2000
Engine: 5.9 24v
Rated Cap: 27
Do these brackets look like they will hold up my Air-Con?

Anyone else do their mini-split in this location?


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Old 06-30-2019, 07:11 PM   #2
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Location: Huntington Beach CA.
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Year: 1991
Coachwork: Bluebird
Chassis: T/C 2000 28 foot Handy Bus
Engine: Cummins 5.9 Mechanical
Rated Cap: 2
Quote:
Originally Posted by Jsneeb View Post
Anyone else do their mini-split in this location?

OK, lets say you weigh 160 pounds. The hammock is supported at either end so the end that is tied to the unit weighs 80 lbs. Now that 80 lbs is tied to either bracket so the static load is only 40 pounds on each bracket. Now imagine that you hit a big bump and now the accelerated mass of that hundred pound condenser is headin down hard. I do not know... but the mount is built for static load. gussets would help immensely IMHO
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Old 06-30-2019, 07:23 PM   #3
Skoolie
 
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Year: 2002
Coachwork: Bluebird
Chassis: Tc2000
Engine: 5.9 24v
Rated Cap: 27
Ehh, thats 40 lb of downward component on each bracket, but there is also a fair bit of sideways component from the hanging mass, but you are right though.
More pictures for detail.





These are absolutely not the brackets that were included with the aircon.
Bolted into the C channel and welded in reinforcement too.
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Old 06-30-2019, 07:29 PM   #4
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Location: Dawsonville, Ga.
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Year: 1999
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Chassis: International
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Quote:
Originally Posted by Jsneeb View Post
More pictures for detail.
These are absolutely not the brackets that were included with the aircon.


The condenser has 4 small mounting feet that are bolted to those after market brackets. Someone else here has done the same. You have to remember the weight of that condenser is suspended by the shock absorbers, so it's not adding the load you think when the bus hits bumps. I'd like to see how the condenser was plumbed?
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Old 06-30-2019, 07:54 PM   #5
Skoolie
 
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Here is how it's plumbed



the plumbing not pretty but she blows beer can cold!



thinking of blowing some foam into this space



Mounted on back wall


This is my first time installing an HVAC.

It runs exclusively off solar and battery power
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Old 06-30-2019, 07:57 PM   #6
Skoolie
 
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Chassis: Tc2000
Engine: 5.9 24v
Rated Cap: 27
Quote:
Originally Posted by o1marc View Post
The condenser has 4 small mounting feet that are bolted to those after market brackets. Someone else here has done the same. You have to remember the weight of that condenser is suspended by the shock absorbers, so it's not adding the load you think when the bus hits bumps. I'd like to see how the condenser was plumbed?
Ahh, yes did I think that those 4 feet are the weakest link in this whole thing. Im going to add a bolt and chain to the under side of the entire unit, such that if the feet fail it wont be able to slide off of the two rails that it sits on. Even if they break off entirely the chain wont let if fall off, maybe jut tip over sideways.
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Old 06-30-2019, 08:10 PM   #7
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Ah hah, the sleeper bracket.I guessed it was the $45 home depot one like I installed a couple of weeks ago. That bracket, heck yes!
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Old 06-30-2019, 08:53 PM   #8
Bus Geek
 
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Quote:
Originally Posted by Jsneeb View Post
Ahh, yes did I think that those 4 feet are the weakest link in this whole thing. Im going to add a bolt and chain to the under side of the entire unit, such that if the feet fail it wont be able to slide off of the two rails that it sits on. Even if they break off entirely the chain wont let if fall off, maybe jut tip over sideways.
Where are you at? If I knew I'd offer you a free back window to replace your broken one. Go to the UserCP and fill out your location in your profile. Makes it easier on us to help you.
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Old 06-30-2019, 09:20 PM   #9
Skoolie
 
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I filled it out. Can you see the details now?
I'm rather far from georgia.

Thank you for the offer! So far it hasn't leaked and i just accepted it as part of Hoodoo's character.
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Old 06-30-2019, 10:03 PM   #10
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Quote:
Originally Posted by Jsneeb View Post
I filled it out. Can you see the details now?
I'm rather far from georgia.

Thank you for the offer! So far it hasn't leaked and i just accepted it as part of Hoodoo's character.
I deleted mine when I added the second door, so I have spares. I see your added info.
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Old 07-01-2019, 07:25 PM   #11
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Oops, after pulling the rear windows from the surplus pile I found them both broken. It was then that I remembered these were the 2 I broke before I learned how to remove them properly.
Attached Thumbnails
20190701_163329.jpg  
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Old 07-02-2019, 10:47 AM   #12
Skoolie
 
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Ah,

Well thank you for the offer marc!
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Old 07-02-2019, 10:49 AM   #13
Skoolie
 
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Follow up with the FEA and design that went into this.
Figured someone might find it valuable.

https://imgur.com/a/rDTER2F#MmO8h0F

----


See entire album but highlights are below.

The FEA is done in solidworks using the SimulationXpress Analysis Wizard. This is a " Demo" tool and doesn't allow you to perform FEA on an assembly, so the calcs were done for a single beam and modeled as a distributed load. Note that the A/C is held up by TWO brackets so double any forces that you see and double the factor of safety to get an idea of the strength of the assembly. Dimensions of the brackets are shown in the hand calcs, steel was assumed to be low carbon/mild steel, cold rolled based off it's texture and smooth finish. I got the steel from the junkyard for free so I do not have it's exact specifications.

Major props to our mechanical engineering Co-Op who had some downtime at work and modeled this for me & did the hand calcs. Im an electrical engineer so not as versed in the mechanics & materials.

Note the deflection in these models is exaggerated for scale. The max actual deflection shown is 2.05mm

Stresses at 2.05mm of endpoint deflection within beam, 1000N force ( 225 lb ). ONE BEAM



Zoomed in view of the fatigue location. Calculated factor of safety for a 1000N force ( 225 lb ), FOS2.4 ( 4.8 for entire assembly of two beams )



I found this model to be the most valuable since it shows where the likely failure point would be. Now I can add it to my list of monthly inspections to inspect this area of the bracket for any bending or deflection. Among others I inspect the battery terminals for corrosion or loose connections, check fluids, air brake bleed-off rate, etc. The monthly inspection list is rather long but necessary to stay ahead of untimely failures and breakdowns.

Hand calcs to backup / confirm model



View inside

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Old 07-07-2019, 12:24 PM   #14
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Chassis: Supercoach
Engine: Detroit 671T
Quote:
Originally Posted by Rivetboy View Post
OK, lets say you weigh 160 pounds. The hammock is supported at either end so the end that is tied to the unit weighs 80 lbs. Now that 80 lbs is tied to either bracket so the static load is only 40 pounds on each bracket. Now imagine that you hit a big bump and now the accelerated mass of that hundred pound condenser is headin down hard. I do not know... but the mount is built for static load. gussets would help immensely IMHO
Splitting hairs here, but the load on the anchors is significantly higher than a simple division of the load on the line. In this case it looks like the angle of the hammock is about 120* so the load on each anchor would be approximately 160lbs. If you split that on the a/c side then each connection is seeing at least 80lbs of force. It’s tough to wrap your head around at first but its very easy to generate massive anchor loads with highlines, and rigging like that. Here is good guide to help explain https://roperescuetraining.com/physics_angles.php
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