3 axle Independent suspension

[Wrknrvr]

If a three axle independent suspension RV goes over a speed bump that is 3" high, how much weight is on a tire when it goes over the high spot.

Let's say there is 3000 pounds on each tire normally.

 

 

Just thinking , Vern

[Alie&Jim's Carrilite]

3000lbs. The IS suspension has 5 1/2 inches of travel.

[skp51443]

It can be higher than the original 3,000 for a couple reasons. The spring rate (pounds per inch of bend) may be rising as the spring compresses which would leave that axle carrying a bit more weight. Another reason would be your equalizers not moving freely or coming to their travel limits, if that happens again you'd be seeing more weight on the high axle.

 

Even when on level ground and towing off level (nose high or low) you can see different loadings on your axles, usually not a lot but enough to be an issue if you are running near your limits. You can fool with that a bit if you can find a scale that will let you move around while weighing. The easy way is to go in for the first weigh with your air hitch empty and weigh each axle as they come onto the scale. Fill the hitch until it touches the top stop and take the same three weights. Usually there will be a difference. You could probably fiddle a way to weigh one side with each axle on a 3" block if you can get to the scale on an angle and just use one corner of the platform.

[rdickinson]

I have IS on my rig and this was a concern but less now since switching to 17.5's and 4800 lb capacity.

[Mark and Dale Bruss]

Regular springs or IS suspension, the issue of an axle taking more load going over speed bumps and other road deviations is why I never liked the idea of just enough tire load capacity which is a common occurrence with trailer manufacturers. Typically, the manufacturers subtract the Pin weight from the GVWR and then divide that number by the number of tires.

 

My rule of thumb is taking the entire GVWR and dividing that by the number of tires. The Pin weight is a safety factor.

[Wrknrvr]

Heading west on I-10 going into Texas the first rest stop is a welcoming center. Once you enter the rest area the pavement separates.

To the left is for for trucks and long vehicles and to the right is for cars.

Have stopped there several times on my way to see Big5r. Although he did not count tires at that time. So we were on our way to other places.

If I remember the speed bump there is about 4" inches high where trucks go. So let's say you are pulling in and you have to stop for something in front of you. Now that was not planned. Yea things happen.

With a springs system that pivots at the center it should help equalize the weight. Some if not all.

 

Now with IS suspension and your one tire on top of that speed bump. Was would the weight be.

 

I added a pressure gauge to a hydraulic jack to see what the pressure would be if the center line of a axle would be raised to different levels.

I normally work till Oct 15 or so and that eliminates going to the HDT rally.

 

I will test an IS suspension this winter if I cannot find one till then. I will compare it to our RS suspension.

I have thought of this before, just did not take time to convert a jack to have a gauge.

 

 

Safe Travels, Vern

[NoDirectionHome]

What is your concern? As previously pointed out, spring rate, tire spring rate at present pressure, and the weight when level all fall into the equation. Until all those are known, you cannot calculate what you are asking. You can test what it is but again, what are you concerned with?

[Nigel]

If you are talking about torsion or non equalizing axles the weight would be 9000 pounds the other two wheels will probably off the ground, that is why they are not recommended for triple axle configurations.

 

Nigel