The Andersen WD Hitch User Thread

[mstephens]

Originally Posted by Ron Gratz

Mark, the WDH causes load to be added to the TV's front axle and to the TT's axle pair. A load equal to the sum of these is removed from the TV's rear axle. This could be shown by downward forces acting on the front and TT axles and an upward force acting on the rear axle. Showing the front axle force and TT axle force acting in opposite directions is not correct.

Also, in the equations on your sketch, the product of a load or weight multiplied by a lever arm would be a torque rather than a force.

Ron

Excellent. Yes, the sketch is a bit crude. In retrospect I probably COULD have shown the upward force (or torque) splitting between the front TV and the TT axles. I puzzled on how to show it graphically and simply. Thanks for the clarification - much appreciated. I just want to keep drilling until I have it right!

[Kosm1o]

The chain is wearng at the bottom inside edge of the square tube. I am pretty sure grinding a champher on the bottom where the wear is taking place will fix it. If not, another solution it to cut the tube on the bottom side and bend the bottom downward matching the angle of the chain. Since, after 5,000 miles the wear isnt that bad, i am going to try the champher fist.

[Ron Gratz]

Originally Posted by crisen

Now your chart says you removed 260 lb from rear axle with 3/16 compression of the bushing. The moment at the ball to do this is 260 lb x 48.7 inches = 12,662 in-lb.

Rick, if you could exert a pure moment on the TV, the moment required to remove 260# from the rear axle (using the front axle as the fulcrum) would be 260# X 106.3" = 27,638 lb-inch.

However, the WDH does not exert a pure momemt. The WDH also reduces the load on the TV via an upward force applied at the hitch head. For the dimensions of Bruce's rig, the upward force applied to the hitch head would be equal to the amount of load transferred to the TT axles -- 260 X 106.3 / (106.3+48.7+164) = 86.64#

This means the moment exerted on the hitch must be 260X106.3 - 86.64X155 = 14,209 lb-inch. The same value can be calculated from 86.64X164 = 14,209.

Weight added to trailer axle = (W.B of TV/ total distance TV front to trailer axle) x weight tranfered from rear axle = (106.3/106.3+48.7+164) x 260 lbs = 86.7 lb.

I think your post said trailer axle went from 3044 to 3120 = 76 lb

The spreadsheet shows the trailer axle going from 3020 to 3120 = 100#. Do you have some updated information?

Ron

[purman]

Originally Posted by Kosm1o

The chain is wearng at the bottom inside edge of the square tube. I am pretty sure grinding a champher on the bottom where the wear is taking place will fix it. If not, another solution it to cut the tube on the bottom side and bend the bottom downward matching the angle of the chain. Since, after 5,000 miles the wear isnt that bad, i am going to try the champher fist.

My chains are also wearing, more so than the bracket. I talked to Dave at Andersen today and I am sending him pictures. Once I get it figured out i will let you know.

[dkottum]

Originally Posted by purman

My chains are also wearing, more so than the bracket. I talked to Dave at Andersen today and I am sending him pictures. Once I get it figured out i will let you know.

If I could sneak in a question relative to the original subject of this thread . . .

Received my Andersen and will install next few days. Am thinking of angling the frame brackets during install so the chains enter the tube more directly. Seems this would minimize the wear?

doug k

[crisen]

Lets just agree to disagree on how it works and leave it at that. The 3044 came from an earlier post and I may have misread it.

Originally Posted by Ron Gratz

Rick, if you could exert a pure moment on the TV, the moment required to remove 260# from the rear axle (using the front axle as the fulcrum) would be 260# X 106.3" = 27,638 lb-inch.

However, the WDH does not exert a pure momemt. The WDH also reduces the load on the TV via an upward force applied at the hitch head. For the dimensions of Bruce's rig, the upward force applied to the hitch head would be equal to the amount of load transferred to the TT axles -- 260 X 106.3 / (106.3+48.7+164) = 86.64#

This means the moment exerted on the hitch must be 260X106.3 - 86.64X155 = 14,209 lb-inch. The same value can be calculated from 86.64X164 = 14,209.

The spreadsheet shows the trailer axle going from 3020 to 3120 = 100#. Do you have some updated information?

Ron

[crisen]

Originally Posted by dkottum

Received my Andersen and will install next few days. Am thinking of angling the frame brackets during install so the chains enter the tube more directly. Seems this would minimize the wear?

doug k

I agree that is definitely what needs to be done, if the chains don't come straight out of the tube of course they would wear. They may wear some anyway if they are straight but by having the side load on the chain that results if they are not straight it would certainly increase wear.

[mstephens]

Originally Posted by purman

Just a note:
They are rated to 2000# but chains are rated at 1/3 of the braking strength. Which means they won't brake till they hit around 6000#

Reason: most people who use chains don't worry about the load they put on them. ie. Logging, trucking, ships, etc. But it would be interesting to see if Andersen will make them with heavier chains.

Another consideration is where the chain is welded to the bolt. I would think this weld would fail before the chain would? Or the clip and pin that hold the chain to the plate. IMO

Everyone is different in this respect, but I would not purposely put a load on a chain past its Working Load Limit (WLL) spec. The specs are not arbitrary, and even though a breaking test might carry a heavier load before breaking, most chain manufacturers are clear about their meaning of WLL spec. They say don't put loads in excess of the WLL on the chain. Here's an example of typical language from a chain manufacturer:

"PEERLESS INDUSTRIAL GROUP PRODUCTS ARE INTENDED TO BE USED AT OR BELOW THE MAXIMUM WORKING LOAD LIMITS SPECIFIED IN CONSTANTLY INCREASING FORCE APPLICATIONS UNDER DIRECT TENSION OR IN A STRAIGHT LINE PULL."

Their web site has some useful information about chain loads, and about chain wear. Here: Chain Working Load Limits, Chain Load, Chain Specs

It's not Gospel, of course, but it is an example of how ratings are interpreted by those who make the products.

I tend to be a bit conservative about such things and I try not to test the limits of systems if I can easily avoid it.

[purman]

Originally Posted by dkottum

If I could sneak in a question relative to the original subject of this thread . . .

Received my Andersen and will install next few days. Am thinking of angling the frame brackets during install so the chains enter the tube more directly. Seems this would minimize the wear?

doug k

This is what I plan to do, but you need to figure away of stopping the bracket from moving. I like the idea of bolting it to the frame. But then again I don't like the idea of drilling holes.

Howie and I talked and his idea was to put some screws against the bolts on the top of the frame rail to stop the bracket from moving. I will be putting them on the top and bottom. These small holes will not compromise the frame as 2 holes through the side would. Bruce H already had the holes there from the factory in his frame.

[dkottum]

Originally Posted by purman

This is what I plan to do, but you need to figure away of stopping the bracket from moving. I like the idea of bolting it to the frame. But then again I don't like the idea of drilling holes.

Howie and I talked and his idea was to put some screws against the bolts on the top of the frame rail to stop the bracket from moving. I will be putting them on the top and bottom. These small holes will not compromise the frame as 2 holes through the side would. Bruce H already had the holes there from the factory in his frame.

Drilling into the frame and using the set screw won't hold it?

doug k

[purman]

Originally Posted by dkottum

Drilling into the frame and using the set screw won't hold it?

doug k

Not the one they supply. But a small hardened bolt on the top and bottom of the frame rail for the bolt that goes through the frame bracket to sit against will stop it from moving.

[dkottum]

Originally Posted by purman

Not the one they supply. But a small hardened bolt on the top and bottom of the frame rail for the bolt that goes through the frame bracket to sit against will stop it from moving.

Do you mean one long bolt going all the way through vertically, or one bolt each on top and bottom and threaded into the frame. What size bolt?

doug k

[dkottum]

Andersen suggests a small weld near the bottom to hold the bracket, anyone done that?

doug k

[purman]

Originally Posted by dkottum

Andersen suggests a small weld near the bottom to hold the bracket, anyone done that?

doug k

No two different bolts, and I need to look at what size yet. The weld is the other option or a hole all the way into the frame for there set screw. Decisions, decisions. I won't know for sure what I want to do till I get it set up and look at it all. I will post plenty of pics.

[idroba]

Originally Posted by dkottum

If I could sneak in a question relative to the original subject of this thread . . .

Received my Andersen and will install next few days. Am thinking of angling the frame brackets during install so the chains enter the tube more directly. Seems this would minimize the wear?

doug k

I don't think that there is any way to angle the frame bracket to make the chains go into the square tube straight on, at all times, and still have access to the large Acme nut. My square tubes are actually angled upwards (see posted photos a number of pages back). When I stopped at the Andersen factory last month, none of the 5 or 6 people there who saw them said anything at all about the way they were mounted. They did not see them as wrong, or a problem. At that time they replaced the ball friction material to fix the creaking noises I had. Those creaking noises went away then for about 70 miles but then came back. The noise was not from the ball friction material, but from the chain in the square tube frame brackets. Most likely, by hooking and unhooking something moved enough to reduce the creaking noises, but they just came back.

Chamfering the square tube might work or flaring it so it is rounded and more able to take the movement from the bushing on the back, but I don't think it is going to be a long term solution. What I see that could work best in all situations is a longer acme thread with the first welded on link outside of the metal tube, then the second link on the chain could be at any angle and cause no problem. This would require a bushing of some sort to support the screw in the front of the square tube. However, that fix would need some way to keep the Acme screw from turning when the nut was tightened.

For now, I am using some spray white lithium grease on the chains where they go into the square tube. I don't know if it eliminates the chain wear, but it does stop the creaking noises when it slides in and out of the tube under the pressure of the bushing in towing mode.

[Mexray]

With regard to chain/tube wear in the frame bracket:

I wonder if Anderson wouldn't be better served to re-design the frame bracket.

The square tube portion could be mounted to the frame bracket as a separate piece, attached with a single, locking bolt so the tube would 'move/rock' or 'hinge' as it were, to line up with the straight 'pull' of the chain...

The bolt would have to be hardened, with perhaps a hardened sleeve to guard against wear, and possibly some small amount of lube would be needed as well...

Just some food for thought...

[Kosm1o]

I tried the set screws first and without drilling a seat for them, there is NO WAY they are going to hold that bracket from slipping. I tried it. After reading the charts showing how many pounds are pulling on those chains, you can see why. I decided drilling a smaller hole clean through the brackets and frame was the way to go and no more a problem than drilling a seat for the set screws. With a heavy 875# tongue weight, I doubt that method would work anyway. The brackets still slipped to the point that the top and bottom bolts of the bracket rest firmly against the frame and thus stop moving at that point. They have not moved since. The angle , however, is slightly forward of what you want but short of adding additional through bolts or welding the brackets to the frame , I don't see how this can be prevented and I also don't see this as being a problem worth the extra measures. The "flared" tube idea to stop the chain wear, sounds great but I am not sure I can do that even in my machine shop. I would recommend filing or grinding a champher on the inside edge of the tube before installation, when you can hold it in a vice and do a good job.

[idroba]

I installed mine at the angle shown in my post #463 of this thread, tightened the set screw down without drilling a hole, and they have not moved since, over 4000 miles with a 700# hitch weight.

I would agree with you Kosm1o that Andersen should think of a new design for the frame brackets as they could use improvement in both how they attach and the way the chain slides in the square tube, causing wear on both parts. Do you think that the chamfer you suggest will hold up to the rubbing or will it simply make it take longer until some chain wear and tube wear occur? As I have noted, I am using a white grease on mine for now.

[Kosm1o]

I am going to take a closer look at the whole chain thing after I hook it up to move it into storage this weekend.

[purman]

Ok so I hope these pictures and my explanation here will help..
Idoroba, Yes if you mount your brackets at a forward angle they will not move. The bolts on the top and bottom of the frame will only let the bracket move so much.

So once it is about 3/8 forward it will not move anymore. I mounted my vertical, and so they moved about 3/8 forward on the bottom to that froward facing angle. Once the bolts on the top and bottom get to a certain angle the frame stops them from going any further.

This angle increases the rubbing of the chains. If the brackets are vertical there is less rubbing, if the brackets angle back even less. You can only angle them back so far, just like they will only go so far forward. You can't get them to angle back far enough to get a perfect straight in line angle.. But you can get it close.

As you can see from these pictures I am going to angle my Brackets backwards so the chain will come out a little more in line with the bottom plate. This will stop the rubbing and noises I was also starting to here. I will also take a file to the inside of the bracket to get any sharp edges out.

This way of mounting will should take care of at least 90% of the chain rubbing.

I also included a picture of the wrench on the bolt to show you can still get to it to tighten it up.