Dual Cam Setup
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...
Forum Discussion
Ron,
Thank you for breaking down the detail response. Very much appreciated. Some comments inserted.
We need mrekim to confirm his loaded TW and how he had the WD adjusted at the time the snap up and frame damage occurred. I was under the impression that he had an 1,100# loaded TW and had adjusted the WD hitch to return the front axle very close to unhitched fender height. I may have mixed that up, we need him to confirm. If all his damage came from only a 500# per side load down onto the WD bar, that is not a comforting thought.
You may have just confirmed with calculations why a single friction bar is not effective on larger/longer trailers and the DC system is. And you were only dealing with the rear side of the DC, not adding front side friction on the opposite side the trailer. It may also help add to why some ORF members have reported their rig had acceptable results on longer trailers when using 2 friction sway bars.
From mrekim’s thread and other recent hitch head and trunnion bar interaction investigation, I no longer can be sure that the WD chain tension will increase as the WD bar rides up the cam pending what the hitch head is doing. There is a hitch head component to this that is still in the discovery stage.
However I still have a “belief” that in a compound angle turn when the inside turn WD bar can unload to zero or closer to zero, there is “some” level of increased tension in the outside turn WD bar. How much tension increase is still unknown. Here it the thought path (may be flawed, but this is how I came to it).
When the TV and TT are on level ground and straight ahead, both WD bars have very close to equal loads. Those WD loads came from the setup of the WD hitch. As a result of this, both left and right WD chain loads are close to the same and the trailer A frame is close to being equally loaded both left and right. So far so good and I think we all agree on this.
Now we come to the point where some DC owners have had snap up failures and in mrekims’ case, A frame failures. A turn has been associated with many if not all snap up failures and even Reese tech service told me in some cases, the snapup can fail with heavy TW’s if the snap up is not bolted. (Note: The Reese tech call was before the newer HD snapup was on the market, the comment relates to the non HD snap up)
Now enter the compound angle turn. When the hitch head rolled and unloaded the inside turn WD bar to zero or near zero, there is only the outside turn bar left to provide any level of WD. If the outside bar load stayed the same, then the truck would of lost 1/2 the WD and the front of the truck would of came up enough the driver “may” feel it. Lighter suspension trucks would fell it more so then stiffer suspension trucks.
I do compound angle turns all the time, and in none of my trucks, 1/2, 3/4 or 1 ton I do not recall the front end going extremely light. We know the WD bar is riding up the cam and we know the rear of the WD bar is rising. We know the trunnion lug on that side is at a down hill angle due to the roll axis. We do not know what the trunnion lug angle in the hitch head did to this equation. That is still an open topic.
Since the TT TW did not change, it is still providing a constant force down on the only WD bar that can produce tension. Since the same TW mass is available to only 1 WD bar it comes down to, will the hitch head angle and the rising rear of the WD bar allow an increase in tension?
While the trunnion lug angle in the hitch head may have relieved some of the WD tension, more of the existing TW is available to be held by the outside turn WD bar. An unknown is, did the hitch head angle change enough to not allow more WD bar tension on the outside turn bar and did the rear of the bar riding up the cam over come the loss in the hitch head?
In order for the snap up to fail like they do, an increased force presents itself to one side of the WD hitch at the WD chain that overloads a non bolted snapup. A hypothesis is, that the outside WD bar rose enough in tension from the compound angle turn to cause the snap up failure. Now the task is, how to quantify that? If this compound angle turn is not creating the force, then what other combination of actions is?
I cannot get the link to fire. Is the link OK or it my PC?
Thanks
John
Thank you for breaking down the detail response. Very much appreciated. Some comments inserted.
Ron Gratz wrote:JBarca wrote:The 500# per bar is a rough approximation based on the OP's scales data which showed 220# returned to the front axle when WD was applied.
---I'm assuming you just picked the 500# as a number to use in the calculation not knowing actual loaded TW's and TV/TT stats. If this correct?
If I had used a value of 1000# per bar, the calculated values would have been doubled.
We need mrekim to confirm his loaded TW and how he had the WD adjusted at the time the snap up and frame damage occurred. I was under the impression that he had an 1,100# loaded TW and had adjusted the WD hitch to return the front axle very close to unhitched fender height. I may have mixed that up, we need him to confirm. If all his damage came from only a 500# per side load down onto the WD bar, that is not a comforting thought.
Ron Gratz wrote:
For purposes of sway control, the longitudinal tension/compression in the WD bar acts like the tension/compression in a friction sway bar -- it resists a change in the angle between TV and TT.
It is interesting to note that a friction sway bar is factory-set to produce a friction force of 1100# compared to the WD bar tension of 2000# which I calculated for the 500# bar load.
You may have just confirmed with calculations why a single friction bar is not effective on larger/longer trailers and the DC system is. And you were only dealing with the rear side of the DC, not adding front side friction on the opposite side the trailer. It may also help add to why some ORF members have reported their rig had acceptable results on longer trailers when using 2 friction sway bars.
Ron Gratz wrote:JBarca wrote:When there is a large TV/TT angle, any upward force on the rear end of a WD bar will tend to rotate the TV about its roll axis and about its pitch axis.
---The large tension on the right side of the A frame appears to be rolling the shank and possibly the truck a little. The shank for sure has a CW tilt as viewed from the TT. With your recent found force magnification in this extreme turn, this possibly might add new light to making a turn with the DC and the large loads that can come from it.
Because the TV's track width is much less than its wheelbase, it is much easier to make it rotate about the roll axis.
When the hitch head is able to rotate CW as shown in your photo, the slope of the front of the WD bar is reduced causing the load on the bar to be reduced.JBarca wrote:In a sharp turn, the slope of the front end of the inside WD bar will be significantly reduced and the load on that bar can go to zero.
---If the inside WD bar is unloaded by some amount, then WD is potentially reduced on left side bar leaving the right side WD to attempt/or add to carrying more of the WD load.
However, that does not mean the load removed from the inside bar will be added to the outside bar.
As your photo shows, on the level surface, there was a left to right tilt of the hitch head because it is relatively easy to rotate the TV about its roll axis.
This means the outside WD bar might actually be subjected to less load than when the TV/TT angle was zero.JBarca wrote:I agree the inside bar can unload to zero, but that is a result of the decreasing tilt of the trunnion axis as the hitch head swings relative to the trailer.
---Does the roll action then even more increase the chain tension and further increase the friction force? Granted this turn is extreme in this case, however a 50 degree turn with a compound angle of 5 to 8 degrees of the hitch head can unload to zero the inside turn WD bar which can be assumed did happen in mrekins case.
From mrekim’s thread and other recent hitch head and trunnion bar interaction investigation, I no longer can be sure that the WD chain tension will increase as the WD bar rides up the cam pending what the hitch head is doing. There is a hitch head component to this that is still in the discovery stage.
However I still have a “belief” that in a compound angle turn when the inside turn WD bar can unload to zero or closer to zero, there is “some” level of increased tension in the outside turn WD bar. How much tension increase is still unknown. Here it the thought path (may be flawed, but this is how I came to it).
When the TV and TT are on level ground and straight ahead, both WD bars have very close to equal loads. Those WD loads came from the setup of the WD hitch. As a result of this, both left and right WD chain loads are close to the same and the trailer A frame is close to being equally loaded both left and right. So far so good and I think we all agree on this.
Now we come to the point where some DC owners have had snap up failures and in mrekims’ case, A frame failures. A turn has been associated with many if not all snap up failures and even Reese tech service told me in some cases, the snapup can fail with heavy TW’s if the snap up is not bolted. (Note: The Reese tech call was before the newer HD snapup was on the market, the comment relates to the non HD snap up)
Now enter the compound angle turn. When the hitch head rolled and unloaded the inside turn WD bar to zero or near zero, there is only the outside turn bar left to provide any level of WD. If the outside bar load stayed the same, then the truck would of lost 1/2 the WD and the front of the truck would of came up enough the driver “may” feel it. Lighter suspension trucks would fell it more so then stiffer suspension trucks.
I do compound angle turns all the time, and in none of my trucks, 1/2, 3/4 or 1 ton I do not recall the front end going extremely light. We know the WD bar is riding up the cam and we know the rear of the WD bar is rising. We know the trunnion lug on that side is at a down hill angle due to the roll axis. We do not know what the trunnion lug angle in the hitch head did to this equation. That is still an open topic.
Since the TT TW did not change, it is still providing a constant force down on the only WD bar that can produce tension. Since the same TW mass is available to only 1 WD bar it comes down to, will the hitch head angle and the rising rear of the WD bar allow an increase in tension?
While the trunnion lug angle in the hitch head may have relieved some of the WD tension, more of the existing TW is available to be held by the outside turn WD bar. An unknown is, did the hitch head angle change enough to not allow more WD bar tension on the outside turn bar and did the rear of the bar riding up the cam over come the loss in the hitch head?
In order for the snap up to fail like they do, an increased force presents itself to one side of the WD hitch at the WD chain that overloads a non bolted snapup. A hypothesis is, that the outside WD bar rose enough in tension from the compound angle turn to cause the snap up failure. Now the task is, how to quantify that? If this compound angle turn is not creating the force, then what other combination of actions is?
Ron Gratz wrote:
In this post, I attempted to address the increase in WD bar load for a sway angle of 5 degrees.
I cannot get the link to fire. Is the link OK or it my PC?
Thanks
John
