Ron Gratz wrote:
First we need to define some dimensions and variables. Let:
a = tow vehicle wheelbase
b = ball overhang (longitudinal distance from TV rear axle to ball)
c = distance from ball to mid-point between the TT's axles
d = perpendicular distance from Andersen chain to center of ball (reported by Andersen owner to be 6.5")
TW = tongue weight
LTT = load transferred to TT's axles
LF1 = load removed from TV's front axle due to TW without WD applied
LF2 = load transferred to TV's front axle when WD is activated
T = Andersen chain tension per chain
M = moment (torque) generated by Andersen chain tension (total for 2 chains)
then (assuming zero pitch-axis rotational friction between ball and coupler)
M = 2*d*T
LTT = M/c = 2*d*T/c
LF2 = LTT*(b+c)/a = 2*d*T*(b+c)/(a*c)
also
LF1 = TW*b/a
If we want to restore a load equal to some percentage (call it FALR) of that which was removed from the front axle, we have:
LF2 = LF1*FALR/100, or 2*d*T*(b+c)/(a*c) = FALR*TW*b/(a*100)
solving for chain tension (per chain) gives
T = FALR*TW*b*c/{2*d*(b+c)*100}
for example, if: b=60", c=200", d=6.5", TW=600#, and you want to restore 50% of the load removed (FALR=50)
T = 50*600*60*200/(2*6.5*260*100) = 1065# per chain
Ron
JBarca wrote:
Hi Ed, Welcome to the discussion! When you came up with 1,000# per chain load, what are the assumptions surrounding this?
John, I don't know how Ed did it, but here is my approach to defining the relationship between tension and load transfer.Hi Ed, Welcome to the discussion! When you came up with 1,000# per chain load, what are the assumptions surrounding this?
First we need to define some dimensions and variables. Let:
a = tow vehicle wheelbase
b = ball overhang (longitudinal distance from TV rear axle to ball)
c = distance from ball to mid-point between the TT's axles
d = perpendicular distance from Andersen chain to center of ball (reported by Andersen owner to be 6.5")
TW = tongue weight
LTT = load transferred to TT's axles
LF1 = load removed from TV's front axle due to TW without WD applied
LF2 = load transferred to TV's front axle when WD is activated
T = Andersen chain tension per chain
M = moment (torque) generated by Andersen chain tension (total for 2 chains)
then (assuming zero pitch-axis rotational friction between ball and coupler)
M = 2*d*T
LTT = M/c = 2*d*T/c
LF2 = LTT*(b+c)/a = 2*d*T*(b+c)/(a*c)
also
LF1 = TW*b/a
If we want to restore a load equal to some percentage (call it FALR) of that which was removed from the front axle, we have:
LF2 = LF1*FALR/100, or 2*d*T*(b+c)/(a*c) = FALR*TW*b/(a*100)
solving for chain tension (per chain) gives
T = FALR*TW*b*c/{2*d*(b+c)*100}
for example, if: b=60", c=200", d=6.5", TW=600#, and you want to restore 50% of the load removed (FALR=50)
T = 50*600*60*200/(2*6.5*260*100) = 1065# per chain
Ron
Hi Ron,
Catching back up on this.
I used your formula,
Ron G wrote:
solving for chain tension (per chain) gives
T = FALR*TW*b*c/{2*d*(b+c)*100}
solving for chain tension (per chain) gives
T = FALR*TW*b*c/{2*d*(b+c)*100}
And check it against my assumptions with my TT & TT.
I my case I used a 1,400# TW, 90% FALR and at the time I estimated "d" to be 8" where you used 6.5" So I tweaked the formula to use 8 to see if it came close to how I backed into it.
Both methods came in close to similar areas.
Using your formula gave 4,050# per chain.
Using my method 3,919# per chain or 131# less than you did.
From here:
JBarca wrote:
In my case I have an actual 1,400# TW and this hitch is rated that high. That is approx. 1,100# at each snap up chain using 28.5” long WD bar or 5,225 ft. lb of torque into the receiver. The Anderson using it’s 8” tow ball would need 7,838# total chain force to create this.
There is some error in this as my Reese Tow beast shank is longer then the Anderson shank but it get’s me in the league of feeling what chain forces are going on with the Anderson.
The 28.5” WD bar compared to the 8” long tow ball is the difference in the mechanical advantage of the 2 hitches for WD. The Anderson will always have to use higher chain force to get the same WD.
In my case I have an actual 1,400# TW and this hitch is rated that high. That is approx. 1,100# at each snap up chain using 28.5” long WD bar or 5,225 ft. lb of torque into the receiver. The Anderson using it’s 8” tow ball would need 7,838# total chain force to create this.
There is some error in this as my Reese Tow beast shank is longer then the Anderson shank but it get’s me in the league of feeling what chain forces are going on with the Anderson.
The 28.5” WD bar compared to the 8” long tow ball is the difference in the mechanical advantage of the 2 hitches for WD. The Anderson will always have to use higher chain force to get the same WD.
I used the spread sheet you sent me many years ago on backing into the chain force of a traditional WD hitch for a given TV and TT. Once you have the chain force you can create the torque in the receiver to the amount of weight returned to the front of the TV. Since I had scale weights and know how my hitch was adjusted, I figured out the torque in the receiver with the Reese then put the Andersen in the same setup to reproduce the same torque, thus creating a chain tension in the Andersen.
Point: 2 approaches that come very close to the same answer.
Also , thanks for the link to the AS site. I read that a while ago but did not follow the latest info.
* This post was edited 05/14/13 04:48am by JBarca *
John & Cindy
2005 Ford F350 Super Duty, 4x4; 6.8L V10 with 4.10
CC, SB, Lariat & FX4 package
21,000 GCWR, 11,000 GVWR
Ford Tow Command
1,700# Reese HP hitch & HP Dual Cam
2 1/2" Towbeast Receiver
2004 Sunline Solaris T310SR
(I wish we were camping!)
BenK wrote:
What isn't or hasn't been discussed is that the regular or traditional WD Hitch
systems 'do' beat up the coupler latch over time WITHOUT the constant contact
and force of the bushings.
The dynamic forces are NOT just from braking, or acceleration, but from all directions during a common road trip over the less than pristine roads, RR crossings,potholes, etc AT SPEED
What would you guys think or guess the forces on the latch is during a severe
whoop-do ?
Where the hitch is driven downwards to stretch the bottom plate to chain to rod to bushing?
There has been reports of the bushing shattering, or when the set screws employed
that they did not hold (allowed that bracket to move)
What isn't or hasn't been discussed is that the regular or traditional WD Hitch
systems 'do' beat up the coupler latch over time WITHOUT the constant contact
and force of the bushings.
The dynamic forces are NOT just from braking, or acceleration, but from all directions during a common road trip over the less than pristine roads, RR crossings,potholes, etc AT SPEED
What would you guys think or guess the forces on the latch is during a severe
whoop-do ?
Where the hitch is driven downwards to stretch the bottom plate to chain to rod to bushing?
There has been reports of the bushing shattering, or when the set screws employed
that they did not hold (allowed that bracket to move)
The back flex as nicknamed that occurs in a WD coming off a high up RR crossing, a big pot hole etc can be harmful to any WD hitch. If done quickly, the traditional WD hitch can crack a hitch head in extreme cases. I was told this by Reese tech service where this has had happen. In another thread about the Pull Rite a while (many few years now) we talked about back flex and when you go slow enough the truck will lift in the back to relief the very high spring force as it equalizes the loads. This helps relieve the pressure so go slow.
The Andersen or the traditional could have hard time in extreme fast back flex situations. While the traditional hitch may fair slightly better due to the operating principal, RV'ers towing heavy TW TT's should try not to bounce hard in those conditions. The dynamic jolt to the system is more than a handful... The Andersen may have a bent bottom chain plate and or urethane spring bracket issues.
BenK wrote:
John, you posted some pictures a while back of your trailer coupler
that had thousands of miles with a traditional WD Hitch system.
It looked very typical vs the miles on it and the latch pawl was
beat up. I've seen much worse and NOTE that is with a traditional WD Hitch system that does NOT have the constant contact that the Andersen architecture has.
John, you posted some pictures a while back of your trailer coupler
that had thousands of miles with a traditional WD Hitch system.
It looked very typical vs the miles on it and the latch pawl was
beat up. I've seen much worse and NOTE that is with a traditional WD Hitch system that does NOT have the constant contact that the Andersen architecture has.
Ben, don't know if you have me mixed up with another member. Yes I took pics of my ball coupler, however the latch shows very little to no wear. There is some light wear on the top formed dome of the coupler. I have a high TW, 1,400 to 1,600# pending loading and I have 1,700# WD bars. I do grease the ball and coupler.
Pic of my Shelby coupler here on page 7 of this thread
And this reply, shows pics of how that coupler works: Shelby coupler action
And more here with the grease wiped off and the latch action Shelby latch action
I have read recently that many have stated that the latch gets slammed when the truck stops with the traditional WD hitch. Well, after seeing mine and the way the dome of the main coupler is formed, I do not agree with this.
A traditional WD hitch exerts a very high downward force on the ball coupler pressing much more than the trailer TW. The only way the TT is going to slam the latch is if the forward force of the TT overcomes the added WD force pressing down on the ball and the TW to pop the tow ball out of that dome and then slide back in the free play to land on top of the latch.
Since my TT brakes are adjusted to stop with the truck, I do not get the trailer pushing the truck 99% of the time. The 1% is when my 7 wire cable fell out and the truck had to do all the work. Even then I caught it early, eased the truck to a stop and there was no slam. (and since then I now always tie the 7 wire cord plug cover over the plug to not hop out, live and learn)
I'm not stating the latch never gets touched, but it is far and in-between on my trailer. There are no shinny or even dull burnish marks on my coupler latch. There are wear marks on the front of the coupler and the top dome.
John
- DW could not turn the nut with my long-handle ratchet, and she has to be able to participate in the process
- Could not lower tailgate with trailer attached
- All the talk about the couplers does have me concerned
- Dealer was willing to swap to the 4-Point for $100
Mike & Tracy Boyd
2013 LaCrosse 318BHS Travel Trailer - Forest River - Prime Time
2006 Silverado 2500HD 4x4 Crewcab SB DMax/Allison
Graduated from 1999 Dodge Ram Extended 2wd 5.9L &
1996 Jayco 1208KB Popup
then from a 2005 Prowler Lynx Ultralite 29BHS
mikedboyd wrote:
For 4 reasons, I traded in my Anderson on an Equalizer 1000# 4-point hitch today.
For 4 reasons, I traded in my Anderson on an Equalizer 1000# 4-point hitch today.
- DW could not turn the nut with my long-handle ratchet, and she has to be able to participate in the process
'Just wondering if I'm missing something here. Provided your hitch is already set up for your situation, and you know how many threads on the bolts should show, why not do this instead: After coupling, raise the tongue to allow easy and fast attachment of the WD chains. This method does not require the use of any long-handled ratchet, and the adjustments are already made.
I used to do the same with my old equalizer hitch on my older TT. Instead of using the snap tool to bring the torsion bars into the L brackets, I would raise the tongue a bit and just slide them in.
The Andersen Hitch has been on my trailer for about a year now and I love it.
2014 Hyundai Santa Fe
2012 R-Vision Crossover 200S
Some not-so-good results are graphically depicted in this post on airforums.com.
Ron
* This post was edited 05/30/13 09:40pm by Ron Gratz *
dennysemn wrote:
........................snip....................
I used to do the same with my old equalizer hitch on my older TT. Instead of using the snap tool to bring the torsion bars into the L brackets, I would raise the tongue a bit and just slide them in.
The Andersen Hitch has been on my trailer for about a year now and I love it.
........................snip....................
I used to do the same with my old equalizer hitch on my older TT. Instead of using the snap tool to bring the torsion bars into the L brackets, I would raise the tongue a bit and just slide them in.
The Andersen Hitch has been on my trailer for about a year now and I love it.
Yours is a pretty typical experience. Most "users" appreciate the convenience, light weight, cleanliness, quiet, and sway resistance of the Andersen hitch. A few people that don't have them seem to have a lot of negatives to say about their value. As pointed out repeatedly, they are not the best at unloading a large amount of weight from an overloaded rear axle. Something with big old spring steel bars is much better suited for that.
TomG2 wrote:
Yours is a pretty typical experience. Most "users" appreciate the convenience, light weight, cleanliness, quiet, and sway resistance of the Andersen hitch. A few people that don't have them seem to have a lot of negatives to say about their value. As pointed out repeatedly, they are not the best at unloading a large amount of weight from an overloaded rear axle. Something with big old spring steel bars is much better suited for that.
dennysemn wrote:
........................snip....................
I used to do the same with my old equalizer hitch on my older TT. Instead of using the snap tool to bring the torsion bars into the L brackets, I would raise the tongue a bit and just slide them in.
The Andersen Hitch has been on my trailer for about a year now and I love it.
........................snip....................
I used to do the same with my old equalizer hitch on my older TT. Instead of using the snap tool to bring the torsion bars into the L brackets, I would raise the tongue a bit and just slide them in.
The Andersen Hitch has been on my trailer for about a year now and I love it.
Yours is a pretty typical experience. Most "users" appreciate the convenience, light weight, cleanliness, quiet, and sway resistance of the Andersen hitch. A few people that don't have them seem to have a lot of negatives to say about their value. As pointed out repeatedly, they are not the best at unloading a large amount of weight from an overloaded rear axle. Something with big old spring steel bars is much better suited for that.
My axle was NOT overloaded and the the Andersen was no good for me. I was a user, not a "user", and there was no way I could have raised the tongue enough to hook up without loosening the nuts. I just finished a 600 mile round trip with an equalizer and it was a much more relaxing drive withe the Equalizer. I have a 1200lb tongue weight and the Andersen couldn't handle it.
* This post was edited 05/30/13 06:34pm by an administrator/moderator *
2004 Ram 3500 2wd Dually
2015 Grand Design Reflection 303RLS
Quote:
---A few people that don't have them seem to have a lot of negatives to say about their value. As pointed out repeatedly, they are not the best at unloading a large amount of weight from an overloaded rear axle.---
Actually, most of the negative comments about the Andersen WDH now are coming from Andersen users, or from former Andersen users.---A few people that don't have them seem to have a lot of negatives to say about their value. As pointed out repeatedly, they are not the best at unloading a large amount of weight from an overloaded rear axle.---
And, the problems being reported by users and former users are not limited just to the inability of the hitch to transfer an amount of load which is commensurate with its rated tongue weight capacity.
Ron
Everyone's opinion is welcome on how this hitch is to them. But please, leave your comments about how others feel about this hitch out of your posting.
Let's give Barney a break, OK? If not, Barney will lock my thread because of the comments about individuals, not about the technical merit of the subject.
New info is still coming in and the learning is interesting. Both the pro's and the con's.
Thanks for being a fellow camper.
John