Dual Cam Setup

[mrekim]

I'm working on setting up a new Reese Dual Cam setup. I think I need a 1" extended ball, and wonder if I would benefit from a 2".

Here's are some photos of where I'm at now:


Side view, I think snap-up can go back a little without having to move the gas mount.




It looks like the cam clears with 6 links, 5 wasn't as good:




Trunion and head bind (less that 45 degrees) (Any reason to NOT center the roll pin? It seems line both are sticking out on one side and are in 1/4" or so on the other.):




Bind on the other side (closer to 90 degrees).

Moderator edit to resize pictures to forum limit of 640px maximum width.

[JBarca]

mrekim wrote:
It looks like this clamping approach holds well. I put some nail polish on the outer plates and the frame and got a couple of hundred miles in with zero movement:

Also, I do plan to revisit the spring bar measurements when time permits....

GREAT!!!

Good trick with the nail polish. Very simple and effective.

[mrekim]

It looks like this clamping approach holds well. I put some nail polish on the outer plates and the frame and got a couple of hundred miles in with zero movement:





Also, I do plan to revisit the spring bar measurements when time permits....

[Ron_Gratz]

mrekim wrote:
Here's another video (slow motion of a right turn). It seems as if the bar deflection decreases at some point in the turn. I wonder if, when the inside bar unloads that the outside bar can unload some too - because rather than the bar bending the suspension is affected?

Dual Cam: Slow Motion Right Turn

When the TV and TT are aligned straight ahead, the left WD bar will be angled about 25 degrees to left of the TV's centerline and the right WD bar will be angled about 25 degrees to right of centerline.
The rearward tilt of both bar trunnion axes will be less than maximum.

When the TV has turned approximately 25 degrees to the right (relative to the TT), the left bar will be parallel to the TV's centerline, and the rearward tilt of its trunnion will be at maximum.
As the TV continues to turn to the right, the rearward tilt will begin to decrease.
This means the bar loading related to trunnion tilt will increase as the TV turns from 0 degrees to 25 degrees, and the loading then will begin to decrease as the turn angle continues to increase.

We also know that, as the TV turns to the right, the load on the outside (left) bar also will increase due to "bar lift" as the bar rides forward and up over its cam.

So, in the range of 0 to 25 degrees, the load on the outside bar increases both due to both trunnion tilt and bar lift.
As turn angle increases beyond 25 degrees, trunnion tilt causes bar load to decrease while bar lift continues load to continue to increase.
My computer simulation indicates the load-decreasing effect of trunnion tilt is greater than the load-increasing effect of bar lift, so the net WD bar load begins to decrease after a turn angle of about 30 degrees.

Ron

[mrekim]

Ron Gratz wrote:

I had envisioned having the wand and gauge on the outside of the cam lift link, but I realize that would make photography very difficult.

I can see if that's possible. I'm not picturing a good place for the gauge.




I'll look at under too - but that might present a ground clearance problem.

Ron Gratz wrote:

Would you be able to turn the link so the u-bolt nuts are on the outside instead of the inside?

I think I can just put a piece of plastic or tape over the u bolt ends to make it smooth. I wish I had though of that while I was in the parking lot doing the test.

Ron Gratz wrote:

If you can figure out how to keep the gauge from hanging up on the u-bolt nuts and keep the wand from hanging up on the u-bolt nuts, chain links, and body parts, we'll be able to quantify the amount of bar tip deflection.

I'll give it another shot.

Ron Gratz wrote:

You also could measure a bar's load-deflection relationship by using the tongue jack to raise the tongue until the bar has zero load. Then unhook the lift chain and let your Sherline scale support the bar tip. As you raise the jack to transfer bar load to the scale, the bar will deflect. That will allow you to get load-deflection data.

I may try that. I don't know if I can lift far enough to get to zero.



Here's another video (slow motion of a right turn). It seems as if the bar deflection decreases at some point in the turn. I wonder if, when the inside bar unloads that the outside bar can unload some too - because rather than the bar bending the suspension is affected?

Dual Cam: Slow Motion Right Turn

[Ron_Gratz]

mrekim wrote:
The gauge needs some tweaks....

Hopefully the info in the video is still useful.

Also, my home brew dual cam mounts don't look like they moved at all. I assume that these turn tests put them near the max propensity to want to slide back and forth?

The videos are extremely informative.
Thank you very much for taking the time to conduct the experiment and make the recordings.

I had envisioned having the wand and gauge on the outside of the cam lift link, but I realize that would make photography very difficult.
Would you be able to turn the link so the u-bolt nuts are on the outside instead of the inside?

If you can figure out how to keep the gauge from hanging up on the u-bolt nuts and keep the wand from hanging up on the u-bolt nuts, chain links, and body parts, we'll be able to quantify the amount of bar tip deflection.

You also could measure a bar's load-deflection relationship by using the tongue jack to raise the tongue until the bar has zero load. Then unhook the lift chain and let your Sherline scale support the bar tip. As you raise the jack to transfer bar load to the scale, the bar will deflect. That will allow you to get load-deflection data.

Thanks again for setting up a great experiment.

Ron

[mrekim]

The gauge needs some tweaks....

Hopefully the info in the video is still useful.

Also, my home brew dual cam mounts don't look like they moved at all. I assume that these turn tests put them near the max propensity to want to slide back and forth?

[mrekim]

Here's a left/right turn:


Dual Cam Left/Right turn

Here's another right turn:


Dual Cam: Slow Motion Right Turn

[mrekim]

If you don't use the tongue jack, this is home far you need to bend the bar by hand:


Dual Cam Lowering Tongue Jack

[mrekim]

JBarca wrote:

Your present TW by your Sherline scale at the time the test is done.

950 Lbs (Measured 2x and got same value)

JBarca wrote:

How much pointer deflection was measured from a relaxed WD bar (no load) to WD engaged just from hitching up?

1 3/8" (From above).

JBarca wrote:

How was WD adjusted on the truck in regards to truck front end position?

Difference between WD and no trailer:

Driver front RAISED 1/16"
Passenger front RAISED 1/4"
Driver rear raised 7/8"
Passenger rear raised 1 1/8"

So the WD is lowering the front a little currently.

The propane tanks are installed and approx 1/2 full. The spare tire is in the back of the Excursion not under the tongue. The front storage is empty as is the storage under the front bed. Hopefully that accounts for the front TV changes vs my previous setup. I'm pretty sure the previous setup - with trailer loaded and ready to go - the front was 0 and RAISED 1/16" when trailer was removed (very slight transfer to front wheels). The tongue weight was 1080 lbs.

[JBarca]

The good news is, the spring deflector setup is working. :C

Your right, a teak to the max travel distance is going to be needed. You need to account for full distance the WD bar can ride up the cam to not bottom out once WD is engaged.

I must say, your camera really gets good resolution.

[mrekim]

I realized that putting the measurement on the bracket would be a problem as the spring bar moves the reference point will move.

I glued on a little reference. This shows the unloaded height. Lines should be at 1/4" intervals so this is at 1 3/8". The lowest line looks like it may be off vs the others so at some point I'll need to check it:




Here's a photo loaded on the TT. It looks like there's 1/2" left. I'm going to have to reset the pointer higher:


Here's the distance of the pointer:

[JBarca]

I'm assuming you have your nifty video camera set up for this?

If the tape does not hold, a stainless steel hose clamp will do the trick, or tie wraps too maybe.

To check the torque arm has not shifted due to the mounting, when you start the test with the truck straight ahead, get a good measurement of the pointer back by the DC. Then when your done driving around, head straight again and recheck that measurement that it comes back to the same place. Then you know the setup is good and the data did not shift in the middle of the test due to the pointer mount shifting.

Some other good data to get if you can.

Your present TW by your Sherline scale at the time the test is done.

How much pointer deflection was measured from a relaxed WD bar (no load) to WD engaged just from hitching up?

How was WD adjusted on the truck in regards to truck front end position?

This will help tells us a little about the normal starting loads on the WD bars.

Ideally there is a pointer on each side and both can be captured in the video at the same time. You can see the combination effect. Maybe the camera is mounted on the camper under the front of the camper looking at both WD bars at the same time? And super would be you can see the scaling in your masking tape so we know how much movement was there. Since you know what zero WD bar load mark is, we can see when the inside turn WD bar unloads or not. May have to get creative with a pointer on the 1/2" edge of the DC chain plate to read the scale from the back. If you can't get both at once, we can still put pieces of the data together to try and sort out the interactions.

I'm really curious now to see the data from this. I'm sure Ron is too.

Good luck

John

[mrekim]

I rigged up a little torque wrench style pointer and am hoping to go out tomorrow for a short test drive of my "clamp on" mounts.


Will this setup add any value to the discussion?

Here's the setup:




And the "mount" to the spring bar:



1/4" spaced lines will go on the blue masking tape.

[JBarca]

The LP tank mount came out good. 🙂 Good job

After seeing my buddies LP tank plate break off going down the highway, it adds a whole new meaning to making sure that plate is held on good. Spot welds are not the way to do it... I'm sure he is still thanking the good Lord he did not have a major issue when the tank fell of and broke the valve open.