BurbMan
Indianapolis, IN
Senior Member
Joined: 09/20/2001
View Profile
Good Sam RV Club Member
|
Time to ante up another $.02....
Ron, I agree with your logic/approach, as Will stated, but your math doesn't pass the sniff test. If the benefit of the HA is marginal with most of the resistive work being done by the TT tires, why does the HA provide such great improvement over a TT with a standard hitch? After all, it's got the same tires.....Tim's calcs seem to be more in ballpark from an expected magnitude.
Sorry I can't offer more specifics to assist, but your meter is definitely reading "out of range" on this one.
Don
|
Ron Gratz
full time RVer
Senior Member
Joined: 12/27/2003
View Profile
|
BurbMan wrote:--- If the benefit of the HA is marginal with most of the resistive work being done by the TT tires, why does the HA provide such great improvement over a TT with a standard hitch? After all, it's got the same tires.....Tim's calcs seem to be more in ballpark from an expected magnitude.
With apologies to all who have seen the following too many times, my answer to Don's question is highlighted in red:
The HA does not "lock up".
The HA does not prevent the trailer from swinging.
Lateral forces on the TT's tires control the swinging.
The HA works by reducing the magnitude of lateral force and by moving the effective point of application closer to the TV's rear axle. This significantly reduces the ability of the TT to "steer" the TV.
This, alone, is sufficient to explain the HA's anti-sway capabilities.
A standard hitch does not reduce the ability of the TT to steer the TV. The HA does.
Ron
|
TeryT
Scottsdale AZ
Senior Member
Joined: 07/04/2003
View Profile
Good Sam RV Club Member
 Offline
|
I'm confused: If it doesn't lock up on the trailer side, what explains the fellow in the video pushing on the side of Hensley model mock-up? Is he not pushing that hard?
Actually in my experience I know it doesn't lock, as I've seen the trailer moving somewhat, while not feeling it much in the TV. But I still wonder about that video & why it appears locked up.
Mighty 4Runner Sport V8 4x4 - over 200k
Hensley Hitch
McKesh Mirrors, Geolandar G015 Tires
Hopkins Insight Brake Controller
Tranny: Hayden Cooler/Fan & CyberDyne Gauge
Mobil 1 Full Synthetic fluids everywhere!
Rockwood 2502 Ultralight TT (3600 lb. dry)!
|
BurbMan
Indianapolis, IN
Senior Member
Joined: 09/20/2001
View Profile
Good Sam RV Club Member
|
Thanks, Ron. Time to unsubscribe from this topic if no new info is being offered. Happy camping everyone!
|
willald
NC
Senior Member
Joined: 07/15/2002
View Profile
Good Sam RV Club Member
Offline
|
BurbMan wrote:Thanks, Ron. Time to unsubscribe from this topic if no new info is being offered. Happy camping everyone!
Welll, I don't think I'm going to call this done and ready to unsubscribe, until I hear Ron address the specific comments you and I made, Don, about how his numbers of 1#/.07% just don't pass the 'sniff' test. A full frontal TT has waaayy too much wind resistance, for those numbers to be accurate.
Will
|
|
|
willald
NC
Senior Member
Joined: 07/15/2002
View Profile
Good Sam RV Club Member
Offline
|
TeryT wrote:I'm confused: If it doesn't lock up on the trailer side, what explains the fellow in the video pushing on the side of Hensley model mock-up? Is he not pushing that hard?
Actually in my experience I know it doesn't lock, as I've seen the trailer moving somewhat, while not feeling it much in the TV. But I still wonder about that video & why it appears locked up.
Well, I think we talked about that video before, but bottom line: that video was a MARKETING video. 'nuff said. ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/smile.gif "smile")
I think we all agree (except for maybe Milt..hehe), that the Hensley does not lock up completely from the trailer's perspective. However, due to the way the linkages work (and several other factors), the Hensley has the effect of VIRTUALLY locking things up from the trailer side, in the sense that it would take an obscene amout of force for the trailer to induce even a little bit of pivoting either direction.
Will
|
TeryT
Scottsdale AZ
Senior Member
Joined: 07/04/2003
View Profile
Good Sam RV Club Member
Offline
|
willald wrote:TeryT wrote:I'm confused: If it doesn't lock up on the trailer side, what explains the fellow in the video pushing on the side of Hensley model mock-up? Is he not pushing that hard?
Actually in my experience I know it doesn't lock, as I've seen the trailer moving somewhat, while not feeling it much in the TV. But I still wonder about that video & why it appears locked up.
Well, I think we talked about that video before, but bottom line: that video was a MARKETING video. 'nuff said.
I think we all agree (except for maybe Milt..hehe), that the Hensley does not lock up completely from the trailer's perspective. However, due to the way the linkages work (and several other factors), the Hensley has the effect of VIRTUALLY locking things up from the trailer side, in the sense that it would take an obscene amout of force for the trailer to induce even a little bit of pivoting either direction.
Will Is there an echo in here? Just how many times do I have to hear this before I get it!!?? LOL As marketing people know well, learning takes place through spaced repetition. That is, hearing or seeing something over & over, in various ways, many times, repeated & repeated again - well you get the idea.
Still would like to see that trailer mock-up on dollies - I'd buy the beer!
|
tluxon
Kirkland, WA
Senior Member
Joined: 08/12/2001
View Profile
Offline
|
TeryT wrote:willald wrote:TeryT wrote:I'm confused: If it doesn't lock up on the trailer side, what explains the fellow in the video pushing on the side of Hensley model mock-up? Is he not pushing that hard?
Actually in my experience I know it doesn't lock, as I've seen the trailer moving somewhat, while not feeling it much in the TV. But I still wonder about that video & why it appears locked up.
Well, I think we talked about that video before, but bottom line: that video was a MARKETING video. 'nuff said.
... Is there an echo in here? Just how many times do I have to hear this before I get it!!?? LOL As marketing people know well, learning takes place through spaced repetition. That is, hearing or seeing something over & over, in various ways, many times, repeated & repeated again - well you get the idea.
Still would like to see that trailer mock-up on dollies - I'd buy the beer!
For reference, here are the pictures showing the application of force in three different manners on the marketing video.
http://www.rv.net/forums/index.cfm/fusea........d/15531727/gotomsg/15541056.cfm#15541056
Here's a post I wrote that Ron was referring to where I described what was happening on the model in the video. http://www.rv.net/forums/index.cfm/fusea........d/15531727/gotomsg/15576122.cfm#15576122
BTW, some of the most useful parts of this thread are found back on those pages. I found it extremely helpful to review that part of the thread last week. If there are some things back there that don't make sense please bring them back to the top so we can hopefully clear them up.
Tim
Tim -
wife Beverly & 2 boys who love camping
2002 K2500 Suburban 8.1L 4.10 Prodigy
2005 Sunnybrook 30FKS HP Dual Cam
Replaced 2000 Sunnybrook 26FK on 8/6/04
|
Ron Gratz
full time RVer
Senior Member
Joined: 12/27/2003
View Profile
|
TeryT wrote:I'm confused: If it doesn't lock up on the trailer side, what explains the fellow in the video pushing on the side of Hensley model mock-up? Is he not pushing that hard?
Actually in my experience I know it doesn't lock, as I've seen the trailer moving somewhat, while not feeling it much in the TV. But I still wonder about that video & why it appears locked up.
Tery,
The guy is pushing at a point between the "TT" wheels and the hitch. Part of his push is distributed to the "TT" wheels and part to the hitch. The lateral force which goes to the hitch is applied to the "TV" very close to the "TV's" rear wheels due to the forward projection of lateral force by the HA's linkage. The front wheel on the "TV" is either a caster wheel or a wheel fixed at 90 degrees to the longitudinal axis of the "TV" and it cannot resist any lateral force.
Two things could cause the "TT" to swing relative to the "TV" under the test conditions:
1. The rear wheels on the "TT" could slide to the right relative to the "TV". However, the lateral push on the "TT" wheels is not sufficient to overcome the static friction forces on those wheels.
2. The rear wheels on the "TV" could slide to the right relative to the "TT". However, the lateral push on the "TV" rear wheels is not sufficient to overcome the friction forces on those wheels.
If the "TV's" rear overhang were representative of real life (i.e. the point of application of lateral force being about 2' behind the "TV's" rear wheels), then the guy's push would cause a CCW torque on the "TV" and it would yaw CCW because the front wheel would offer no resistance.
Since the non-representative test fixture causes the "TT" lateral force to be applied at the "TV's" rear wheels, there is no moment which would cause a relative yaw between the "TT" and "TV. Since there is no moment, there is no yaw and the hitch appears to be "locked".
Ron
* This post was
edited 09/06/05 04:04pm by Ron Gratz *
|
Ron Gratz
full time RVer
Senior Member
Joined: 12/27/2003
View Profile
|
Willald wrote:All right!!!! We're making progress!! Finally, Ron does agree that there is 'more' added, by the way the Hensley forces the trailer forward when pivoting either way. Before, he refused to accept that. We're making progress at least. Now we just gotta agree on exactly HOW MUCH more is added.
Will,
Actually, I agreed with you back in this post. You just didn't realize it (or maybe you just didn't like my answer). I presented a numerical example showing that your "reel in" effect could increase the tongue tension by 40# and that would require an obscene lateral force increase of 0.5# to compensate.
To be continued ---
Ron
* This post was
edited 09/06/05 04:19pm by Ron Gratz *
|
|
|
|
