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12-26-2007, 06:57 PM
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#61
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Join Date: Dec 2004
Posts: 8,812
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hi ron and welcome to the asf...
i've seen your posts on other forums and the nice diagrams.
it's not obvious, but we have covered how the haha works in many other threads.
just not this one.
till now.
cheers
2air'
__________________
all of the true things that i am about to tell you are shameless lies. l.b.j.
we are here on earth to fart around. don't let anybody tell you any different. k.v.
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12-26-2007, 10:11 PM
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#62
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Rivet Master
2005 25' Safari
Salem
, Oregon
Join Date: Mar 2006
Posts: 8,369
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Hi, nice diagrams, but it's all "Hong-Kong" to me. In other words, it might as well be printed in Chineese. Maybe a picture or diagram, in scale, showing the relationship between the tow vehicle and trailer would work better. And a side by side compairison [non Hensley hitch] showing the different positions of tow vehicle, tow ball, pivot points [vertual and real] and trailer. Also, at the 10 degree angle, looks like "Jack-Knife" to me. And will the tow ball actually move between 5" and 6.4"?
__________________
Bob 2005 Safari 25-B
"Le Petit Chateau Argent" Small Silver Castle
2000 Navigator / 2014 F-150 Eco-Boost / Equal-i-zer / P-3
YAMAHA 2400 / AIR #12144
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12-27-2007, 07:26 AM
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#63
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4 Rivet Member
Livingston
, Texas
Join Date: Dec 2007
Posts: 394
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Quote:
Originally Posted by ROBERTSUNRUS
Hi, nice diagrams, but it's all "Hong-Kong" to me. In other words, it might as well be printed in Chineese. Maybe a picture or diagram, in scale, showing the relationship between the tow vehicle and trailer would work better. And a side by side compairison [non Hensley hitch] showing the different positions of tow vehicle, tow ball, pivot points [vertual and real] and trailer. Also, at the 10 degree angle, looks like "Jack-Knife" to me. And will the tow ball actually move between 5" and 6.4"?
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Good suggestions. Actually, you're one step ahead of me. The comparison diagrams will be next.
Your "Jack-Knife" comment made me realize the diagrams need further explanation. The longitudinal centerline of the tow vehicle is on the plot's vertical axis. This means that in all diagrams, the tow vehicle is pointed up with its centerline in the left-right center of the plot. An angle of 10 degrees should not present a jackknife situation. Perhaps the next set of diagrams will better explain this.
Yes, the HA's tow ball can move laterally plus or minus 5" and can move forward 6.4" relative to its "centered" position. The HA is based on a 4-bar linkage. The rear unit which holds the tow ball is one of the links. In order to have a yaw angle between the trailer and the tow vehicle, the rear unit must simultaneously rotate and move laterally. The diagrams show the relative movement among the links.
Ron
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12-27-2007, 07:49 AM
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#64
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2 Rivet Member
Commercial Member
Currently Looking...
Oxford
, Michigan
Join Date: Dec 2007
Posts: 95
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This is why us engineers aren't allowed to talk on the phone with customers. I love Ron's diagrams. The 4 bar linkage is not as difficult as it appears. Build one out of toothpicks, Legos, whatever you like. With nothing "pinned down," it can rotate anywhere you like. Those are "degrees of freedom." By fixing one or more points, you limit the degrees of freedom. The trapezoidal (as opposed to a simple rectangle) design allows the tow vehicle to maintain a mechanical advantage over the trailer.
Listen, it's just a tool, like any other. A set of pliers puts a tight grip on an object in one direction, falls off in the other. The linkage system at the heart of the Arrow has been in existence for a long time, someone just decided to try it in a hitch application.
By the way, the Lego video was done by a Hensley customer without any prompting from us. We stumbled across it and put it on the web site. Maybe I'll put Ron's drawings on there. Physics always was my favorite subject (really).
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12-27-2007, 10:03 AM
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#65
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Ready-to-Travel
2012 30' International
Walkerton
, Virginia
Join Date: Dec 2003
Posts: 3,166
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Ron,
Your last sentence explains a lot. The video is worth much less than you paid for it and detracts from your product.
Other than that...
Pat
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12-27-2007, 01:37 PM
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#66
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2 Rivet Member
Commercial Member
Currently Looking...
Oxford
, Michigan
Join Date: Dec 2007
Posts: 95
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But it gives grown men a great excuse to play with Legos!
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12-27-2007, 01:54 PM
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#67
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Rivet Master
1967 28' Ambassador
1963 19' Globetrotter
1970 29' Ambassador
Waukesha
, Wisconsin
Join Date: May 2007
Posts: 1,180
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Quote:
Originally Posted by pmclemore
The video is worth much less than you paid for it and detracts from your product.
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I agree... it likens the product to "snake-oil" maybe you could re-do the video in an accurate depiction of the hitches function.
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12-28-2007, 07:29 AM
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#68
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2 Rivet Member
Commercial Member
Currently Looking...
Oxford
, Michigan
Join Date: Dec 2007
Posts: 95
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Joking aside, I agree. We've made several attempts to show how it works. It seems it's never enough info or too much. The price of computer animation has come down quite a bit in the last few years, though, so I may have to re-visit that. We have the same problem with our TrailerSaver 5th wheel hitch.
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12-30-2007, 08:18 AM
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#69
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4 Rivet Member
Livingston
, Texas
Join Date: Dec 2007
Posts: 394
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Comparison Diagram -- Hensley, PullRite, Conventional
Quote:
Originally Posted by ROBERTSUNRUS
---Maybe a picture or diagram, in scale, showing the relationship between the tow vehicle and trailer would work better. And a side by side compairison [non Hensley hitch] showing the different positions of tow vehicle, tow ball, pivot points [vertual and real] and trailer.
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Following is a diagram showing basic features of the Hensley Arrow, PullRite, and "conventional" hitches. The tow vehicle is modeled after a Suburban with wheelbase = 130". The distance from the rear axle to the ball of a conventional hitch is assumed to be 65".
The HA's ball, when centered, is assumed to be 77" behind the rear axle. This means the HA's VPP, when the linkage is centered, will be 77-52 =24" behind the TV's rear axle. At a yaw angle of 4 degrees, as shown in the diagram, the HA's VPP has moved rearward about 24" and laterally about 19".
For comparison, the PullRite's pivot point remains fixed at 12" behind the rear axle. I have assumed the PR adds 60" of length to the TT's tongue.
The enlarged diagram shows the different pivot points and the relative positions of the TT's tongue when using the different hitch systems. The unique feature of the HA is its variable virtual pivot point location shown by the yellow path.
The way in which each hitch transfers lateral force from the TT to the TV is a primary factor in yaw stability. The distance from the TV's rear axle to the point of application of lateral force is a "lever arm" over which the lateral force acts to generate a "steering torque" on the TV.
For the conventional hitch without sway control, the lever arm in this example is 65". For the PullRite, the lever arm is 12". For the HA, the lever arm varies from about 24" when the linkage is centered, to about 48" at a 4-degree yaw angle, to about 70" at a 15-degree yaw angle. However, if the TV had a shorter rear overhang, then both the HA and the conventional would have a shorter lever arm.
Discussions about how the HA works usually involve comments about the linkage being "locked" so as to prevent the TT from swinging behind the TV. There is no locking mechanism. The TT and TV are connected via four roller bearings. The HA's rear unit is free to translate and rotate relative to the front unit.
If you could lift the tires of a PullRite-equipped TT off the ground, you could swing the TT with no resistance from the hitch. If you lifted the tires of a TT coupled via a convential hitch with no sway control, you could swing the TT with no resistance. And, if you lifted the tires of a HA-equipped TT, you could swing the TT with no resistance from the HA's linkage.
It is also a myth that a HA-equipped TT cannot "steer" the TV. As long as the "lever arm" is not zero, a TT can steer the TV if the TT exerts lateral force. With a PullRite, it appears there is no steering because the steering torque is significantly reduced. With a HA, it appears there is no steering because the HA also reduces the steering torque. Contrary to what you might read in advertising literature, the HA does NOT 'make the vehicle combination "think" and "act" like a straight unit, a straight truck if you will.'
Ron
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12-30-2007, 09:55 AM
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#70
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1 Rivet Member
Currently Looking...
Rochester Hills
, Michigan
Join Date: Dec 2007
Posts: 15
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Quote:
Originally Posted by Ron Gratz
.............................
Discussions about how the HA works usually involve comments about the linkage being "locked" so as to prevent the TT from swinging behind the TV. There is no locking mechanism. The TT and TV are connected via four roller bearings. The HA's rear unit is free to translate and rotate relative to the front unit.
If you could lift the tires of a PullRite-equipped TT off the ground, you could swing the TT with no resistance from the hitch. If you lifted the tires of a TT coupled via a convential hitch with no sway control, you could swing the TT with no resistance. And, if you lifted the tires of a HA-equipped TT, you could swing the TT with no resistance from the HA's linkage.
It is also a myth that a HA-equipped TT cannot "steer" the TV. As long as the "lever arm" is not zero, a TT can steer the TV if the TT exerts lateral force. With a PullRite, it appears there is no steering because the steering torque is significantly reduced. With a HA, it appears there is no steering because the HA also reduces the steering torque. Contrary to what you might read in advertising literature, the HA does NOT 'make the vehicle combination "think" and "act" like a straight unit, a straight truck if you will.'
Ron
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I am just relying on a full scale model I build and it doesn't support what you are telling here..
I hold the TV side of the model in my RH and try to twist or move the TT side of the model (simulating yaw, sway...) then the entire model moves.. This trapezoid is LOCKED once you induce a movement from the TT and the trapezoid is flexible once you induce a move from the TV.
__________________
ZenfookPower
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12-30-2007, 10:13 AM
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#71
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ProPride Industries, Inc.
Commercial Member
Holly
, MI
Join Date: Nov 2007
Posts: 642
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Quote:
Originally Posted by Ron Gratz
And, if you lifted the tires of a HA-equipped TT, you could swing the TT with no resistance from the HA's linkage.
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Sorry, Ron, this is not correct. Stop by an RV show sometime and lift up the rear unit of the demo and see if you can swing it with no resistance. You won't be able to do it and that is with only the light weight of the demo unit tow vehicle.
__________________
ProPride Hitch
"The Most Advanced Generation in Trailer Sway Elimination"
Holly, MI
Tu ne cede malis
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12-30-2007, 06:29 PM
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#72
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4 Rivet Member
Livingston
, Texas
Join Date: Dec 2007
Posts: 394
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Quote:
Originally Posted by ZenfookPower
I am just relying on a full scale model I build and it doesn't support what you are telling here..
I hold the TV side of the model in my RH and try to twist or move the TT side of the model (simulating yaw, sway...) then the entire model moves.. This trapezoid is LOCKED once you induce a movement from the TT and the trapezoid is flexible once you induce a move from the TV.
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I built a full scale model of the linkage four years ago. Everything I've posted about the kinematics of the HA's linkage is supported by my physical model.
I fully agree that if you "twist" the TT side of the model while restraining the TT side from moving laterally, you can make the linkage appear to be "locked". However, I was not talking about applying a "twisting" to the TT side.
I stated that if you lifted the tires of a HA-connected TT off the ground, you could push laterally on the TT and make it swing. If you want to simulate this on your model, simply hold the TV side and push laterally (not "twisting") on the TT side. Then you will see that the linkage does rotate freely and the TT side does swing laterally.
Ron
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12-30-2007, 07:33 PM
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#73
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ProPride Industries, Inc.
Commercial Member
Holly
, MI
Join Date: Nov 2007
Posts: 642
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Quote:
Originally Posted by Ron Gratz
I built a full scale model of the linkage four years ago. Everything I've posted about the kinematics of the HA's linkage is supported by my physical model.
I fully agree that if you "twist" the TT side of the model while restraining the TT side from moving laterally, you can make the linkage appear to be "locked". However, I was not talking about applying a "twisting" to the TT side.
I stated that if you lifted the tires of a HA-connected TT off the ground, you could push laterally on the TT and make it swing. If you want to simulate this on your model, simply hold the TV side and push laterally (not "twisting") on the TT side. Then you will see that the linkage does rotate freely and the TT side does swing laterally.
Ron
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Ron, I have lifted the rear end of the demo unit, with an actual hitch on it, more times than I care to remember. Conservatively speaking, I've done this 5,000 times in my life. The links do not allow that end of the demo, the TT end, to swing freely from side to side. I'm just stating a physical fact here not commenting on theories and models.
__________________
ProPride Hitch
"The Most Advanced Generation in Trailer Sway Elimination"
Holly, MI
Tu ne cede malis
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12-30-2007, 08:15 PM
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#74
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1 Rivet Member
Currently Looking...
Rochester Hills
, Michigan
Join Date: Dec 2007
Posts: 15
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Quote:
Originally Posted by Ron Gratz
I fully agree that if you "twist" the TT side of the model while restraining the TT side from moving laterally, you can make the linkage appear to be "locked".
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Yes, that is correct...It is locked.. "is" is the affirmative of what appears to be "locked"..(let's not start discussing what "is" is... )
Quote:
Originally Posted by Ron Gratz
I stated that if you lifted the tires of a HA-connected TT off the ground, you could push laterally on the TT and make it swing. If you want to simulate this on your model, simply hold the TV side and push laterally (not "twisting") on the TT side. Then you will see that the linkage does rotate freely and the TT side does swing laterally.
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But that is NOT how reality is..My TT tires stay on the road..
The yaw or sway induced by the TT will NOT be transmitted to the TV because of the locked condition of the trapezoid linkage..
What are you trying to prove that the HA/3P doesn't control/eliminate sway..???
__________________
ZenfookPower
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12-30-2007, 08:18 PM
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#75
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Moderator dude
1966 26' Overlander
Phoenix
, Arizona
Join Date: Apr 2002
Posts: 7,501
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Agree to dissagree or action will take place!
>>>>>>>>>>>>>>>Action
__________________
1966 Mercury Park Lane 4 DR Breezeway 410 4V, C-6, 2.80 - Streamless.
1966 Lincoln 4 door Convertible 462 4V 1971 Ford LTD Convertible 429 4V Phoenix ~ Yeah it's hot however it's a dry heat!
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12-30-2007, 08:38 PM
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#76
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Join Date: Dec 2004
Posts: 8,812
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Quote:
Originally Posted by Action
Agree to dissagree or action will take place!....
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i agree!
oh wait, i disagree!
well u know what i mean...
cheers
2air'
__________________
all of the true things that i am about to tell you are shameless lies. l.b.j.
we are here on earth to fart around. don't let anybody tell you any different. k.v.
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12-30-2007, 09:18 PM
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#77
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Rivet Master
2005 25' Safari
Salem
, Oregon
Join Date: Mar 2006
Posts: 8,369
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Quote:
Originally Posted by Action
Agree to dissagree or action will take place!
>>>>>>>>>>>>>>>Action
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Hi, come on "Action" let them be; It's getting really interesting. No harm done.
__________________
Bob 2005 Safari 25-B
"Le Petit Chateau Argent" Small Silver Castle
2000 Navigator / 2014 F-150 Eco-Boost / Equal-i-zer / P-3
YAMAHA 2400 / AIR #12144
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01-01-2008, 03:33 PM
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#78
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Airstreamin and luvin it
Commercial Member
2005 25' Safari
Northwest Panhandle
, The Sunshine State/WBCCI 6637
Join Date: Jul 2005
Posts: 1,524
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Simplified
I am guessing this is as simple as it gets.
__________________
CHANGE IS GOOD.LIFE IS GREAT!
It just cant get any better than that.
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01-01-2008, 03:37 PM
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#79
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Rivet Master
2006 25' Safari FB SE
St. Cloud
, Minnesota
Join Date: Aug 2003
Posts: 13,280
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My head is spinning. That YouTube link was what started post #1 in this thread. Its okay though Devo -- you've got a rally to go to. When Michelle left my driveway 3 weeks ago she wondered if the ice around her Airstream's tires would keep it frozen in place. Inquiring Floridians want to know?? Or not.
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01-01-2008, 03:40 PM
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#80
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Airstreamin and luvin it
Commercial Member
2005 25' Safari
Northwest Panhandle
, The Sunshine State/WBCCI 6637
Join Date: Jul 2005
Posts: 1,524
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Hitch
Sorry about that.To much going on I guess.I have been getting lost in the forum quite a bit lately.I dont know what snow is down here but we are about to get a blast of really cold air that we have not had in quite a few years from what I remember.the next three days are going to be cold.Well...For me anyways.
__________________
CHANGE IS GOOD.LIFE IS GREAT!
It just cant get any better than that.
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