A fellow camper bud showed me this. It's new and different.
Anyone using one?
Andersen WD hitches
A U-tube video with the factory guy explaining it. You have to get past MR Truck doing his intro. Interesting 5th wheel hitch too.
http://www.youtube.com/watch?v=xvM7mCnqmwo&feature=related
It looks like this
I'll hold my comments for a short while to not cloud your thoughts. Ideally we can find someone here using one to quiz them on it.
John
Anyone using one?
Andersen WD hitches
A U-tube video with the factory guy explaining it. You have to get past MR Truck doing his intro. Interesting 5th wheel hitch too.
http://www.youtube.com/watch?v=xvM7mCnqmwo&feature=related
It looks like this
I'll hold my comments for a short while to not cloud your thoughts. Ideally we can find someone here using one to quiz them on it.
John
Glad you guys got to a common point
Have been PM'd to keep it simple so as to not have to PM me more...those folks
got lost with the last few posts
Years ago during discussions of the GMT800 receiver found that 'consumed' made
sense to the folks talking to and have been using that ever since,
but with highly trained and detailed eyeballs...that is too loosey goosey a term
The last few posts discusses that in detail and here it is baked down in
layman's terms that have worked for me on those PM discussions
All traditional receivers use the cross tube (whether square or round) is a
torque tube.
The Pin Box has the shank and hitch head levered upwards by the WD Hitch system
spring bars (round and trunnion) and on the Andersen system, by the chain
Both imparts a lever arm force (we call that a moment in eng speak) on the
shank head.
The top portion at the ball end is pushed towards the front of the TV
The bottom portion opposite of the ball end is pulled backwards.
This will have a twisting force (torque) on the TV's receiver cross tube because
the pin box transmits that WD force to the point where the Pin Box is attached
to the cross tube of a TRADITIONAL receiver cross tube
Where the difference in the GMT800 receiver is how they managed this force. It
also uses the cross tube as a torque tube, but they also use the bumper as a
transfer component.
That bumper transfer component consists of several pieces and is the food chain
to the TV frame. There is compliance (movement) through out that food chain
My assumption is that since they used the bumper, they then reduced the cross
tube wall thickness thinking it didn't need as much any more
Since the food chain to the TV frame via the bumper has so many components that
are BOLTED together, there is movement both bending the components and movement
in the bolted joints
The GMT800 receiver pin box moves much more than most traditional
designed receiver pin boxes. So much that some (many) bend beyond
their elastic point and into their plastic point and does not snap back. It stays bent.
Now switch to the WD spring systems and think this is where Andersen either
by design or luck that they chose a plastic spring.
All of the WD Hitch systems I've ever seen has a limited or small travel for
their springs. The Andersen system the smallest or shortest spring travel. It
would be interesting and germane if we could get hold of all of their spring
rate curves (lbs vs travel). Better yet if we could find their release speeds
and getting to porpoising that the Andersen does not, to date, have or is reported
The number of links on the traditional systems and the number of threads on the
Andersen system are indicators of how much tension is on the spring bars/trunnions
and plastic bushings.
That then transfer forces to the receiver pin box rotating it upwards, that then
creates torque on the cross tube
If that pin box is allowed to rotate too much, the travel of the spring system
of the WD Hitch runs out of gas, so to speak and is where I came up with 'consume'
during PM discussions with members here
True, not consumed, but runs out of distance or whatever you wish to call it
Don't believe that the GMT800 receiver pin box moves more than most other traditional
designed receivers...here are some links and pics
GM Hitch Deflection Measured - Comments Welcome
John's comment on his GMT800 receiver:
One more thread on this: Receiver on GM seems to tilt up - best replacement?
Yes, just a few, but never the less, shows how 'some' of these GMT800 receiver
pin boxes do bend and this image shows how it 'tried' to transfer to the bumper
bottom, that then transfers to the inside bumper cross brace, that then transfers
to the bumper bracket to the TV frame rail.
Here is the diagram made up years ago during one of the discussions on the GMT800
receiver showing the force vectors (my opinion).
Here is another made up years ago with my opinion on quality of production of
the GMT800 receiver. Mainly my forensics on how that one broke off the pin box
from the cross tube. Actually had the guy send me that pin box and took hundreds
of pictures and made up this diagram during that dicussion
That is because of the amount of movement (flexing or porpoising) that the GMT800
has and mainly with those who tow heavy...the folks with lighter loads don't
report as many issues.
Here is the latest post on this exact issue, but GMT900. GMT900 pickups
continue to have this design, albeit bolstered by addition of gussets
inside the 'U' bracket. GMT900 SUV's have a more traditional receiver
but they continue to have it inside the bumper, which has crash crumple
duties and why it is limited to 1,000 lb tongue weight in WD mode
GMT-900 Hitches: How Many Have Replaced It? 2012May
To bring this back to the Andersen Hitch system...since the Andersen system
has a shorter spring travel, any receiver that has lots of travel will have
the Andersen system run out of gas (spring travel) so that it will no longer
be able to 'WD' the tongue weight
John's comment on his GMT800 receiver:
and my coinage of 'consumed', which is a misnomer, but gets the idea
across to non-technical folks that I've been talking to...
Have been PM'd to keep it simple so as to not have to PM me more...those folks
got lost with the last few posts
Years ago during discussions of the GMT800 receiver found that 'consumed' made
sense to the folks talking to and have been using that ever since,
but with highly trained and detailed eyeballs...that is too loosey goosey a term
The last few posts discusses that in detail and here it is baked down in
layman's terms that have worked for me on those PM discussions
All traditional receivers use the cross tube (whether square or round) is a
torque tube.
The Pin Box has the shank and hitch head levered upwards by the WD Hitch system
spring bars (round and trunnion) and on the Andersen system, by the chain
Both imparts a lever arm force (we call that a moment in eng speak) on the
shank head.
The top portion at the ball end is pushed towards the front of the TV
The bottom portion opposite of the ball end is pulled backwards.
This will have a twisting force (torque) on the TV's receiver cross tube because
the pin box transmits that WD force to the point where the Pin Box is attached
to the cross tube of a TRADITIONAL receiver cross tube
Where the difference in the GMT800 receiver is how they managed this force. It
also uses the cross tube as a torque tube, but they also use the bumper as a
transfer component.
That bumper transfer component consists of several pieces and is the food chain
to the TV frame. There is compliance (movement) through out that food chain
My assumption is that since they used the bumper, they then reduced the cross
tube wall thickness thinking it didn't need as much any more
Since the food chain to the TV frame via the bumper has so many components that
are BOLTED together, there is movement both bending the components and movement
in the bolted joints
The GMT800 receiver pin box moves much more than most traditional
designed receiver pin boxes. So much that some (many) bend beyond
their elastic point and into their plastic point and does not snap back. It stays bent.
Now switch to the WD spring systems and think this is where Andersen either
by design or luck that they chose a plastic spring.
All of the WD Hitch systems I've ever seen has a limited or small travel for
their springs. The Andersen system the smallest or shortest spring travel. It
would be interesting and germane if we could get hold of all of their spring
rate curves (lbs vs travel). Better yet if we could find their release speeds
and getting to porpoising that the Andersen does not, to date, have or is reported
The number of links on the traditional systems and the number of threads on the
Andersen system are indicators of how much tension is on the spring bars/trunnions
and plastic bushings.
That then transfer forces to the receiver pin box rotating it upwards, that then
creates torque on the cross tube
If that pin box is allowed to rotate too much, the travel of the spring system
of the WD Hitch runs out of gas, so to speak and is where I came up with 'consume'
during PM discussions with members here
True, not consumed, but runs out of distance or whatever you wish to call it
Don't believe that the GMT800 receiver pin box moves more than most other traditional
designed receivers...here are some links and pics
GM Hitch Deflection Measured - Comments Welcome
John's comment on his GMT800 receiver:
"The amount of deflection of the GM hitch was amazing"
One more thread on this: Receiver on GM seems to tilt up - best replacement?
Yes, just a few, but never the less, shows how 'some' of these GMT800 receiver
pin boxes do bend and this image shows how it 'tried' to transfer to the bumper
bottom, that then transfers to the inside bumper cross brace, that then transfers
to the bumper bracket to the TV frame rail.
Here is the diagram made up years ago during one of the discussions on the GMT800
receiver showing the force vectors (my opinion).
Here is another made up years ago with my opinion on quality of production of
the GMT800 receiver. Mainly my forensics on how that one broke off the pin box
from the cross tube. Actually had the guy send me that pin box and took hundreds
of pictures and made up this diagram during that dicussion
That is because of the amount of movement (flexing or porpoising) that the GMT800
has and mainly with those who tow heavy...the folks with lighter loads don't
report as many issues.
Here is the latest post on this exact issue, but GMT900. GMT900 pickups
continue to have this design, albeit bolstered by addition of gussets
inside the 'U' bracket. GMT900 SUV's have a more traditional receiver
but they continue to have it inside the bumper, which has crash crumple
duties and why it is limited to 1,000 lb tongue weight in WD mode
GMT-900 Hitches: How Many Have Replaced It? 2012May
To bring this back to the Andersen Hitch system...since the Andersen system
has a shorter spring travel, any receiver that has lots of travel will have
the Andersen system run out of gas (spring travel) so that it will no longer
be able to 'WD' the tongue weight
John's comment on his GMT800 receiver:
"The amount of deflection of the GM hitch was amazing"
and my coinage of 'consumed', which is a misnomer, but gets the idea
across to non-technical folks that I've been talking to...
Ron Gratz wrote:
We had three days of rain here in the twin cities of Marinette, WI, and Menominee, MI.
Thanks Ron, We had a good Memorial day. Here in Central OH it was โfull onโ summerโฆ 90 to 92 deg F all 3 days. Glad we had the AC in the camper to escape the heat and be able to sleep at least.
Ron Gratz wrote:
Receiver torsional stiffness does not enter into the relationship between WD spring force and load transfer.
JBarca wrote:
---When you do reach the WD spring force to be the same on a less efficient receiver after over adjusting the hitch, then yes the WD on the TV will be the same.---
Ron Gratz wrote:
I think we're saying the same thing -- if the WD spring force is the same, the load transfer will be the same -- regardless of receiver torsional stiffness.
I think we also agree that, if receiver torsional stiffness is sufficiently low, physical restrictions on ball mount tilt and/or lift chain length might limit WD bar force.
However, 100% of the torque which is generated by the WD bars will be transmitted to the tow vehicle via the receiver. It has nowhere else to go. Nothing is "consumed" or "eaten up" by the receiver.
Yes, we do agree. Once the WD bars gets loaded up enough, the weight will move. The words "consumed" or "eaten up" by the receiver I believe were used to describe what can and has occurred on some OEM receivers when excess flex is observed.
When I had my 2003 K2500 Suburban I had a level of what I would state is โreceiver inefficiencyโ occurring. This may have been the beginning of realizing this vintage TV with the torsion bar front end suspension is not going to squat equal and GM did not want it too either. Just in 2003 they never put that in the ownerโs manual and a 39 page post on RV.net was bornโฆ. By 2004 GM did list in the manual to not over compress the front end.
In my case I was up against a level of receiver to frame flex and possibly a level of excess receiver twist. I was losing the ability to transfer the hitch WD forces to the front of the truck. I did change the receiver to a Putnam XDR which had different adjusting attributes.
I did experience what I would describe is a large amount โreceiver inefficiencyโ on my buddies 2002 Yukon (shorty WB Yukon). He had a Draw-tite hitch with the DC and he came to the house and we setup the hitch in my yard. He tried on his own to get this right but was having trouble as the WD settings where not responding like others have had.
He had a Travel-Star camper with an approx. 850# TW as measured by my Sherline tongue scale IRRC. This is now maybe 6 years ago, maybe more. He had 1,200# WD bars. We totally reset the hitch so the DC would not be in a binding condition in turns then started to adjust the head tilt to gain proper WD on the TV which in this case was to return the front axle to unhitched fender height.
His receiver was not responding like others I had adjusted. A washer of head tilt to the rear would result in not much to almost no movement on the front of the truck. It took almost 3 washers worth of tilt to get the front to change much. Granted in this case I did not have the dial indicator out measuring fender heights, we were using a tape measure. There was a zone of very high โreceiver inefficiencyโ were hitch head tilt movements would not yield fender changes on the front of the TV to expected results. Once we started approaching 4 to 5 more washers we had an abrupt amount of movement.
On this setup once all washers that the head tilt pin could accept and an additional chain link we over drove the front end beyond unhitched and had to back off. This soft 1500 suspension you could overdrive the front end much quicker than the 2500.
When we were all done and the TT leveled out, the front was above 1/8 to 3/16โ of unhitched height I stepped back and looked at the hitch head. WOWโฆ to my surprise we had used up all of the head tilt and the hitch shank was very high up in the air. This Draw-tite head of that era had approx. 12 degrees of rear tilt with full washers. The head was tilted to the rear approx. 10 to 12 degrees with the shank close to that far above unhitched. That is a lot of rear head tilt and much more than normally needed to get a WD hitch to adjust properly with strong WD bars and a lighter TW.
In this case the receiver was rated at 1,500# in WD mode against an 850# loaded TW using 1,200# WD bars. That combo should not of given the end results it did. I told him this receiver is not responding correct, we have used almost all of the hitch settings and it still is not right. He took it home, ordered a Putnam Class 4 had his dealer installed it for him and even the dealer was shocked. The system adjusted out like it should with the receiver change.
I wish we had more time, I would of really liked to study that receiver to see where the loss of torsional twist was going. The end result was the pin box to the receiver tube and the receiver tube to the frame brackets rotated further then normally observed even on my K2500 original Burb receiver with a 1,200# TW which was the same series receiver.
Ron Gratz wrote:
As a side note -- the VESC V-5 Regulation and the corresponding SAE Standard indicate that a rotation of up to 5 degrees is acceptable.
Ron
Yes I know you found this spec a long time ago and was really good info. I would have to go back and find it to see if they state where the 5 degrees starts. I have found when a loaded TW is in the 900 to 1,200# range that the dead weight on the ball can rotate the pin box down approx. 5 degrees from unhitched position. Once WD is adjusted to return the TV front axle to unhitched height the pin box can be rotated up 2 to 3 degrees from the unhitched position. See here, NOTE, this is a 1,200# TW, using 1,200# WD bars, 2003 K2500 Burb, Putnam XDR receiver rated at 1,700# in WD mode.
Now see the same camper, same loaded 1,200# TW, same 1,200# WD bars, 2005 F350, Ford OEM receiver rated at 1,250# in WD mode.
The F350 OEM Super duty receiver has a tighter shank to pin box fit then the Putnam XDR did which made the XDR need more tilt.
I know that the suspensions are different between the K2500 Burb and the F350 as well as the TV WB. However the receiver ratings where a lot different too. I have not yet found a relationship between TW WD mode rating to when a receiver exhibits this high inefficiency problem. Some have lots of rating and the TW is low in comparison while some are at the high end of the ratings and work great.
Your statement about;
Ron Gratz wrote:
However, 100% of the torque which is generated by the WD bars will be transmitted to the tow vehicle via the receiver. It has nowhere else to go.
Yes it is true where 100% of the torque is going into the receiver, however it is not always being reflected at the front wheels of the TV. It is being lost in the process. The connection between the hitch shank and the front of the TV front end has more flex in some setups then others. Once the lost motion is accounted for the WD adjustments start showing up at the front axle, hopefully before you run out of hitch adjustment.
When some folks talk about "consumed" or "eaten up" by the receiver, โI believeโ they are referring to lost motion or excessive rotation in the receiver system. Some GMโs from year 2000 to 2006, some Toyota 750# WD rated receivers on PU's and some F150's have experienced this effect to name a few I have run across. You can generally spot the issue by the hitch shank pointing up at a very high angle, 5 plus degrees from unhitched, trying to get the TV front end close to unhitched height.
This lost motion or excessive rotation in the receiver system may be in spec however you may also have a WD hitch that cannot tolerate it. I do not know if the TV OEM's and the WD hitch OEM's ever connected on what "normal" is suppose to be.
On the Andersen WD hitch I would suspect this high inefficiency of the receiver system would show up as seen by having a larger degree of thread exposed behind the urethane springs and by a large angle pointing up on the hitch shank.
John
