jcsteele

Building an air ride hitch

39 posts in this topic

jc, bronze bushings do not perform well in an application where there is impact combined with only partial rotation (such as swing arms). They like to see 360 degree rotation and no impact, otherwise they will work flow and become egg shaped in ID.

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1 minute ago, phoenix2013 said:

jc, bronze bushings do not perform well in an application where there is impact combined with only partial rotation (such as swing arms). They like to see 360 degree rotation and no impact, otherwise they will work flow and become egg shaped in ID.

That was my limited understanding of bronze bushings as well.... thanks for the confirmation!!

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1 hour ago, phoenix2013 said:

jc, bronze bushings do not perform well in an application where there is impact combined with only partial rotation (such as swing arms). They like to see 360 degree rotation and no impact, otherwise they will work flow and become egg shaped in ID.

Is THAT why the pivots on idler arms on combine belt tension pulleys wear out so fast!?   Add an offset load, and they wear crooked real fast.  Then the pulley sits in at an angle, then the belt runs off....     Steel to steel and grease @ 10 hours---never have an issue with those pivots, come to think of it.

I've always found it extremely interesting that sometimes WOOD is the best bearing material!  I know of one application...rotary motion, slow speed (10 rpm) , fairly large surface, low load, lots of dirt.   Wood blocks lasted for 5-6000 hours--with NO grease or anything.  Didn't really wear the shaft much either.   The company tried replacing the "old fashioned wood" with greasable cast aluminum blocks, bronze bushings, & seals.  Had to be greased every day and lasted < 1000 hours.   Everybody took them back off and put wood back on.  Not to mention the wood cost $20...the other $200.  Isn't engineering FUN?

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jkennel, one industry that had a bitch of a time with this problem was the excersize equipment manufacturers, since most of that machinery moves over some angle and not fully around.

The solution was composite bushings. But there is a lot of engineering that goes into that because there are multitude of composite materials and performance specs to choose from.

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On 6/19/2017 at 6:58 PM, 13speed said:

Is there anyone on this forum that is not a damn Engineer:rolleyes: Henry and I were literally talking about that earlier this afternoon and I told him I am just a dumb truck driver and cannot possibly keep up with all of you super brainiacs :huh: 

Maybe after I pay for my hitch I can talk him in to making me a honorary Engineer wannabe B)

 

PS, A ET will be a bit more than 2-3K......just sayin

Shucks 1 3........you don't want to be a E n G i N e A r........all the girlz will giggle at you and a lot of you try to do will end up in the dumpster (per Henry posts) and IF.........Just IF......by chance you stumble and get anything to halfa$$ to work......some darn geezer here will come up with 13 ways to "improve" what you did to make it work.........trust me

1 3 , your far better to be president than being a engineer ........few folks like engineers......

 

Drive on..........(better to be a geezer than.........E n G i N e A r.)

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8 hours ago, Dollytrolley said:

Shucks 1 3........you don't want to be a E n G i N e A r........all the girlz will giggle at you and a lot of you try to do will end up in the dumpster (per Henry posts) and IF.........Just IF......by chance you stumble and get anything to halfa$$ to work......some darn geezer here will come up with 13 ways to "improve" what you did to make it work.........trust me

1 3 , your far better to be president than being a engineer ........few folks like engineers......

 

Drive on..........(better to be a geezer than.........E n G i N e A r.)

But you guys have such big brains....like the alien guys in "Mars Attacks", How can I not be jealous? 

As far as being President....I don't think I could do any worse than the current guy:huh:...few folks like him either:lol::lol::lol:

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This is an example of where You don't have to engineer anything.  Speak to an engineer at a supplier and let them specify a solution for you.  There are multiple places where you can apply this practice.

Edited by NoDirectionHome

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On 6/20/2017 at 11:12 PM, jcsteele said:

at least in my brain, so far the only thing I can't get ironed out is an adequate pivot material... I would make it greasable but I am trying to find an adequate hardened bushing in the 1.5" to 2" ID size range.

My 2 cents of encouragement:

http://websales.amtektool.com/viewitems/ejector-pins-blanks-sleeves-bushings/shoulder-bushings

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Product developments is the most expensive task corporations undertake. R & D departments usually consume anywhere from 10-15% of the corporate budget. In start-up companies it's 100% of the budget until you have something to sell and then you are suppose to get it all back in 2-3 years selling the stuff. It's known as ROI, Return On Investment. Most of the time it doesn't happen, the original developer gets replaced by a management team that knows how to make money, they might keep him around or he looses the whole thing.

I spent my whole life doing this. Real companies with real R & D department, that had to pay guys like me, will set aside $100K on product development that will end up with a $500-1,000 product, $250K to come up with $3,000-4,000 product. Military is different, A system that went into 11 navy ships I was designing had a budget of $18 million.

I spent three months designing the ET and $6,500 out of pocket, the guy I was working for then (I saw him in the mirror) payed me nothing for my time (the cheap bastard). Considering what my engineering pay grade was at the time, I don't believe ROI has been met yet, 10 years later. Although I'm hoping that shortly I might claim that I earned $5 bucks an hour for the effort.

Why did I do it? Because, I'm an ornery old bastard, because I could, because I was retired then and had ton of free time on my hand, I was bored and needed a challenge and there was that nagging question of the old age, do I still have the stones, coohones, etc., etc., ...............................

Edited by phoenix2013

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16 hours ago, NoDirectionHome said:

This is an example of where You don't have to engineer anything.  Speak to an engineer at a supplier and let them specify a solution for you.  There are multiple places where you can apply this practice.

Ummmm, that might work in a few instances, but highly doubtful that you would get any useful information for a product as complicated as an air hitch.

As a couple examples of what I am talking about, what sort of load factors are you going to design to?  What sort of force is a (10,000, 20,000 or whatever capacity trailer load you are designing to), going to place on the load carrying arms or pivot components, such as Heim joints, in a fore and aft plane,  with the fifth wheel at it's maximum travel limits in a vertical plane.

For rub bar material selection, what sort of lateral forces could you reasonably predict that the fifth wheel plate will exert on the rub rail material while the fifth wheel is moving in a vertical plane, such as reacting to a bump in the road, with high lateral loading in a tight corner with braking forces applied.

It may not seem that complicated to some folks and as expressed on here already, plenty of folks have already built there own version of a hitch.  Still it is important to remember that we are talking about something that is imperative to be sound and safely built. 

At a minimum, if you poorly design it, you will go through a lot of raw material perfecting your design.  Or blow through consumables such as heims that wear out in a couple hundred miles.

 

Edited by VegasFlyer

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