Community Forums

swberry · 12-12-2015, 05:31 AM

Maybe this has been brought up before, but if you are towing a vehicle behind the coach won't the weight attached to the rear of the coach transfer some of the weight off the front axle to the rear? So if the coach weighs in at the max gross weight on the front axle (sitting static on scales) couldn't you reasonably assume that the load on the front axle will be less when underway and towing a vehicle?

C.Martin · 12-12-2015, 05:59 AM

Quote:

Originally Posted by swberry

Maybe this has been brought up before, but if you are towing a vehicle behind the coach won't the weight attached to the rear of the coach transfer some of the weight off the front axle to the rear? So if the coach weighs in at the max gross weight on the front axle (sitting static on scales) couldn't you reasonably assume that the load on the front axle will be less when underway and towing a vehicle?

You're correct. But a large number of people choose to also operate their motor coach without a trailer...or towing a vehicle 4-down (zero tongue weight on coaches hitch).

If it's of any consolation...we were in Nappanee to see our Ventana on the production line a few days ago. I caught a glimpse of a new Dutch Star driving across the campus towing a test trailer with a load of concrete blocks stacked onboard. You can draw your own conclusions; I honestly think they are working on the problem.

Gordon Dewald · 12-12-2015, 09:07 AM

Quote:

Originally Posted by swberry

Maybe this has been brought up before, but if you are towing a vehicle behind the coach won't the weight attached to the rear of the coach transfer some of the weight off the front axle to the rear? So if the coach weighs in at the max gross weight on the front axle (sitting static on scales) couldn't you reasonably assume that the load on the front axle will be less when underway and towing a vehicle?

Many of the larger trailers are purchased with tri-axles. The tri-axle is a different animal than a single or tandem axle in weight distribution.

We have a tri-axle stacker that we load to a bit over 13,000 lbs. Unless I drive the car so it touches the front the maximum weight I can get on the tongue is 800 lbs.

Crasher · 12-12-2015, 12:13 PM

I have manual regulator valves for controlling the air pressure in the tag airbags. When not towing our trailer, it takes 40 psi to get the 75/25 ratio I want for the drive/tag loads. The steer axle is then at 14,600#. Rated at 15,600#. When towing the trailer with 1500# of tongue weight, the tag needs 50 psi to achieve the 75/25 ratio, and the steer axle is still at 14,600#. The tag load goes from 5200# up close to 7000# and the drive up some, but the steer stays the same. I've done a lot of testing and being able to set my own pressures allows me to get whatever I want or need.

cwsqbm · 12-17-2015, 11:08 AM

Quote:

Originally Posted by swberry

Maybe this has been brought up before, but if you are towing a vehicle behind the coach won't the weight attached to the rear of the coach transfer some of the weight off the front axle to the rear? So if the coach weighs in at the max gross weight on the front axle (sitting static on scales) couldn't you reasonably assume that the load on the front axle will be less when underway and towing a vehicle?

You can't assume that for two reasons:

First, we're not taking about a vehicle AT max gross weight on the front axle. AT max gross weight is fine, its OVER that is the problem.

Second, the amount of weight removed from the front axle is much less than the tongue weight of the trailer. Consider the frame of the motorhome as a lever. The amount removed off the front axle is going to be roughly the tongue weight multiplied by the distance from tag axle to hitch divided by the distance from the tag to the steer axle. At best, you'd get 1/6th the tongue weight off the front axle. So, a 1500 lb tongue weight (a very heavy trailer) would only take 250 lbs off the front axle which isn't enough to fix the issues in this thread.

Gordon Dewald · 12-17-2015, 11:14 AM

Quote:

Originally Posted by cwsqbm

You can't assume that for two reasons:

First, we're not taking about a vehicle AT max gross weight on the front axle. AT max gross weight is fine, its OVER that is the problem.

Second, the amount of weight removed from the front axle is much less than the tongue weight of the trailer. Consider the frame of the motorhome as a lever. The amount removed off the front axle is going to be roughly the tongue weight multiplied by the distance from tag axle to hitch divided by the distance from the tag to the steer axle. At best, you'd get 1/6th the tongue weight off the front axle. So, a 1500 lb tongue weight (a very heavy trailer) would only take 250 lbs off the front axle which isn't enough to fix the issues in this thread.

Currently it would be less than that. The tag ride height will force weight from the hitch to the steering axle using the drive axle as a fulcrum. At best there would be very little difference. That is why they are talking about a proportioning valve.