New Owner Question re WDH

[Wavery]

Originally Posted by Bill

Not just rear-end sag, but also (and perhaps more importantly) front-end rise. As you mentioned, front-end rise reflects the unloading of the wheels that do all of the steering most of the braking, and this is an invitation to disaster.

At risk of starting a wildfire, I'll also say that simply measuring rear-end sag encourages people to install helper springs and air bags, to level out the vehicle. However, simply raising the rear end of the vehicle an inch or two does nothing to unload the rear suspension (tires, wheel bearings, shocks, etc), leaving it potentially overloaded even though "it looks good". And more importantly, it does nothing to re-load the front end, replacing the weight that is missing there.

Bill

Exactly correct. Most WDH manufacturers suggest that you measure the wheel well height of the TV (front and rear) unloaded, then measure again loaded. This will give you an idea of the effects of the trailer load (static).

The longer the WB of the vehicle (combined with distance from the hitch ball to the center of the rear axle), the less the effect will be but there will always be some effect.

Think of the rear axle of the TV as the fulcrum point of a lever. The load force on the trailer ball will effect the upward effort on the front axle. It makes no difference how much spring is applied to the fulcrum point.

The amount of "unloading" to the front wheels is easily calculable if you have your trailer tongue weight and the amount of weight loaded aft of the axle (which is a little harder to calculate):
http://www.engineeringtoolbox.com/levers-d_1304.html

What must be kept in mind is that these figures only tell you what the "Static" load is. As the vehicle drives down the road, there is "Shock" loading that must be considered. In extremes cases, shock-loading could be so extreme as to nearly lift the front wheels off the ground.

When using a WDH, this loading is distributed both to the front wheels of the TV and the axle of the trailer. Again, static load is easily measured and shock-loading can be extreme to both the front axle of the TV and the trailer axle.

The attached pic is kinda silly but it demonstrates the theory rather well.

What # bars would be recommended for a 2619 TM ?

We kind of high jacked the OP thread, so I apologize for that.

[scrubjaysnest]

Some may find this of interest.

http://auto.howstuffworks.com/auto-p...on-systems.htm

[Bill]

Originally Posted by harveyrv

Think of the rear axle of the TV as the fulcrum point of a lever. The load force on the trailer ball will effect the upward effort on the front axle. It makes no difference how much spring is applied to the fulcrum point.

Illustration here

http://www.trailmanorowners.com/foru...&pictureid=441

Bill

[BobSan]

Hi Bill I just order a trunnion style wdh kit.Is 31 inches bars too long for a 3124 ks.
Thank you
Bob

[Mr. Adventure]

Originally Posted by harveyrv

Exactly correct. Most WDH manufacturers suggest that you measure the wheel well height of the TV (front and rear) unloaded, then measure again loaded. This will give you an idea of the effects of the trailer load (static).

The longer the WB of the vehicle (combined with distance from the hitch ball to the center of the rear axle), the less the effect will be but there will always be some effect.

Think of the rear axle of the TV as the fulcrum point of a lever. The load force on the trailer ball will effect the upward effort on the front axle. It makes no difference how much spring is applied to the fulcrum point.

The amount of "unloading" to the front wheels is easily calculable if you have your trailer tongue weight and the amount of weight loaded aft of the axle (which is a little harder to calculate):
http://www.engineeringtoolbox.com/levers-d_1304.html

What must be kept in mind is that these figures only tell you what the "Static" load is. As the vehicle drives down the road, there is "Shock" loading that must be considered. In extremes cases, shock-loading could be so extreme as to nearly lift the front wheels off the ground.

When using a WDH, this loading is distributed both to the front wheels of the TV and the axle of the trailer. Again, static load is easily measured and shock-loading can be extreme to both the front axle of the TV and the trailer axle.

The attached pic is kinda silly but it demonstrates the theory rather well.

Harvey,
The amount of unloading on the front wheels is more easily and more accurately determined on the scale. But the diagram in the link you posted also shows the importance of overhang versus wheelbase. Wheelbase is good for towing stability, overhang is bad, and the wheelbase to overhang ratio of tow vehicles is probably what really counts, more than just the wheelbase by itself.

1200# bars are for redistributing a load. 1200# springs are for carrying one. They aren't meant for linear arithmetic with each other, though they do make additions and subtractions at the load points.

The shock loading you'd like us to be considering is nothing more than the normal, dynamic, much-higher-than-static loads that are considered in the design of all moving vehicles. There is no special case for weight distributing hitches. I keep considering how the tongue load that overloads your rear axle in your world of non-WDH shocking shock forces is magically not a problem for you while these incalculable but considerable forces of shock keep getting posed as an important but vague matter of inconsiderable concern for the rest of us. I'm getting very high readings on the BS meter again.

But we don't need to disagree that the effect would be exactly identical for the case of 600# bars that you don't use versus the case of 1200# bars that you don't use.

[Mr. Adventure]

Originally Posted by Redhawk

What # bars would be recommended for a 2619 TM ?

We kind of high jacked the OP thread, so I apologize for that.

They have changed the bar ratings all over the place in the last few years, and I have to wonder how much of the change has been in bars and how much has been in labeling. 600# should be plenty, so bars rated 400 to 800# would probably be perfect. A higher rating could theoretically make the ride a little stiffer, but its been working great for me.

[Wavery]

Originally Posted by Mr. Adventure

Harvey,
The amount of unloading on the front wheels is more easily and more accurately determined on the scale. But the diagram in the link you posted also shows the importance of overhang versus wheelbase. Wheelbase is good for towing stability, overhang is bad, and the wheelbase to overhang ratio of tow vehicles is probably what really counts, more than just the wheelbase by itself.

1200# bars are for redistributing a load. 1200# springs are for carrying one. They aren't meant for linear arithmetic with each other, though they do make additions and subtractions at the load points.

The shock loading you'd like us to be considering is nothing more than the normal, dynamic, much-higher-than-static loads that are considered in the design of all moving vehicles. There is no special case for weight distributing hitches. I keep considering how the tongue load that overloads your rear axle in your world of non-WDH shocking shock forces is magically not a problem for you while these incalculable but considerable forces of shock keep getting posed as an important but vague matter of inconsiderable concern for the rest of us. I'm getting very high readings on the BS meter again.

But we don't need to disagree that the effect would be exactly identical for the case of 600# bars that you don't use versus the case of 1200# bars that you don't use.

I'm not sure why your rudeness but just because you can't comprehend something doesn't make it "BS" my friend. Maybe you might consider getting your meter adjusted. It seems to be scewed towards a lack of understanding......

[Mr. Adventure]

Originally Posted by harveyrv

I'm not sure why your rudeness but just because you can't comprehend something doesn't make it "BS" my friend. Maybe you might consider getting your meter adjusted. It seems to be scewed towards a lack of understanding......

I assure you that I'm comprehending you clearly. I enjoy your posts when they come from your actual experience. You're a better mechanic than I will ever be. But you are no engineer. I really, really would like to see you stop making up stuff just to create fear or concern in other people so that you can make rules for them to follow which you don't/won't apply to yourself or to your own situation.

[mjlaupp]

Originally Posted by harveyrv

.....What must be kept in mind is that these figures only tell you what the "Static" load is. As the vehicle drives down the road, there is "Shock" loading that must be considered. In extremes cases, shock-loading could be so extreme as to nearly lift the front wheels off the ground.

When using a WDH, this loading is distributed both to the front wheels of the TV and the axle of the trailer. Again, static load is easily measured and shock-loading can be extreme to both the front axle of the TV and the trailer axle.....

Please use the correct terms in the correct context as defined by the SME - Society of Mechanical Engineers. The following is from the ToolingU, Mechanical Systems Training web page: http://www.toolingu.com/definition-5...hock-load.html

Static Load - "A type of load that maintains the same direction and degree of force during operation." = Tow vehicle and/or TrailManor at rest.

Dynamic Load - "A type of load that changes in the direction or degree of force during operation." = Tow vehicle and TrailManor in motion, springs and WDH load bars working within their normal limits.

Shock Load - "A type of load characterized by extreme speed and a tremendous amount of force." = Tow vehicle and TrailManor in motion, Springs, shocks and/or WDH load bars hitting a limit such as the TV rubber bump stop on the axle, a coil spring fully compressed or extended, or a shock fully compressed or extended.