Buying Advice Ballast Box vs Wheel Weights vs Filled Tires

[JerryK]

Me, I figure you guys have all your wood in and stacked, and are bored/waiting for snow or something to do besides all these sprung/unsprung weight posts.... So, I am doing my best 'snow dance'....so get her greased up.......... And, if it is a bad winter.....blame it on me.... [ I am in the two pair of wheel weights/something heavy on the 3pt, and the last thing I would ever do to one of my tractors is fill the tires crowd...if you want to continue... ]

 

[SPYDERLK]

Calling it Sprung/Unsprung weight uses the reference to a "spring" as a convenient dividing line between the kit above the axle and the wheel/tire combo as most all rolling stock has springs and it is a convenient way to refer to things, an arbitrary dividing line, that's all.

Springs are a device installed on rolling stock ever since the days of horse and carriage and are there for one reason and one reason only; they make the ride easier on the rear end of the passenger.

Their presence or absence has no bearing on the physics of a single, dual, three, four or eighteen plus wheeled vehicle. Tires and wheels are unspung weight and all that lies above the axle is sprung weight, whether it bounces or jars the rear end of the operator. Springs or lack thereof also have no relation to roll-over, except in the case of soft springs and excessive body roll which shifts the CG to the "downhill" side and makes a roll over more likely. Tractors, with no springs see no shift in CG, it stays put along the vertical axis to the ground but that weight is still sprung, even though it is fixed with relation to the axle.

I threw in the 3pt weight as a fifth wheel because it looked right but I'm willing to agree that it may not be unsprung if any of its weight is carried by the structure above the axle, which it is. It does lower CG, but that does not make it unsprung.

This is my last post on the subject, believe what you care to believe. There is a vast body of knowledge on the subject used by vehicle manufacturers and modifiers. Some applications attempt to reduce unsprung weight and others find an increase a benefit. In tractors, increased unsprung weight is a definite benefit and high CG sprung weight a definite liability.

Wrong. Without a suspension that allows relative motion between wheels and chassis the only sprung weight is on the seat cushion.
larry

 

[Brandon1107]

I think to take some of the fire out of this thread it should be bearing weight and non-bearing weight. As in applied to the wheel bearings.

 

[ovrszd]

I think to take some of the fire out of this thread it should be bearing weight and non-bearing weight. As in applied to the wheel bearings.

A few posts back I asked the contributors in this discussion to explain what they would call the tire/wheel weight on a tractor. You are the only one that's offered anything. So I'm going with you, bearing versus non-bearing. Everyone seems to get sprung out of shape over sprung versus unsprung for some reason. I use sprung versus un-sprung only as a description of weight location, has nothing to do with the presence of a spring.

Jerry, I do have all my wood in so I'm good in that area!! I also am always reluctant to fill tires. My Brother's new L3240 is getting Rim Guard, 47 gallons per tire, 11 lbs per gallon for $230. So he's getting 1034 lbs of weight at a cost of 22 cents per pound. Last I checked wheel weights were running a minimum of $1.00 per pound. So,, $230 versus $1034. Rim Guard is non-corrosive, can be ran with tubeless tires and will accept tire plugs if needed. Pretty efficient "non-bearing" weight.

 

[ovrszd]

Wrong. Without a suspension that allows relative motion between wheels and chassis the only sprung weight is on the seat cushion.
larry

Larry, this is how we turn this into an argument instead of a discussion. Recovery offered a very good explanation and your first response was "wrong" without giving his explanation any credit.

 

[SPYDERLK]

Larry, this is how we turn this into an argument instead of a discussion. Recovery offered a very good explanation and your first response was "wrong" without giving his explanation any credit.

I bear him no ill will. I just dont want a good explanation of "how people are using a descriptive term" to have any appearance of excusing them using it wrongly. When it is used wrongly the true import of the descriptive term is diluted, and to prevent it being lost entirely, must be repeatedly reintroduced. In the meantime those not having a clear understanding of the situation are likely to court trouble by passing it on or using it.

Between unsprung weight and sprung weight there is always a suspension to allow relative motion between the two. Springs or some other similar device is used to allow the motion and then follow up by restoring nominal clearance so there will be room to again allow the relative motion. The purpose of all this is to smooth out impulses. Our most common experiences with it are on cars, and motorcycles. ... The gist of the situation is that bumps are an irresistable force. They force the wheel to move up and over them. The wheel has to do this. ..RIGHT NOW since it cant go thru the bump. The heavier the wheel and the faster its going the more force the bump exerts to shove the wheel "out of its way" quickly enuf- so the more energy is stored in the wheel. If the wheel is going to stay in contact with the ground something has to absorb this energy and keep it pushed down. That would be the vehicle suspension [springs and shocks]. At speed there are extreme upward accelerations of the unsprung element - far beyond 1G. Were Gravity the only restoring force that wheel would be in the air far too long. But with suspension, gravity is aided by the energy [FxD] the spring stores during the deflection caused by the bump. So the wheel is forced back to the ground very quickly by both Gravitypulling on it and the spring pushing on it [reacting against the chassis] --- and kept from turning into a bouncing ball by the energy absorbed by the shocks. Thus, in proportion, the lighter the unsprung elements [wheels, axles, etc], the less the sprung element [chassis] reacts to the bump transients. ...Better handling.

In a rigid "suspension" everything is unsprung weight. When you encounter a bump fast enuf that the wheel must accelerate upward anywhere near 1G the whole rigidly connected chassis must follow - and the only force available to restore weight balance is the force of that one G acting on the entire mass of rigid body. Downward [restoring] acceleration can be no more than 1G. Restoration thus happens much slower with the rigid system. Careening quickly becomes a apt descriptor. The quick transmission of the full bump impulse, and the slow recovery are highly dangerous at speed and fortunately offer maximum discomfort.
larry

 

[racolton]

Excellent description Larry, you must be a Mechanical Engineer (or some related field) because you explained the difference perfectly!

 

[SPYDERLK]

Excellent description Larry, you must be a Mechanical Engineer (or some related field) because you explained the difference perfectly!

Thanks! Feel free to add if you see a need for clarification. The more people that actually know true stuf the better. Makes for a stronger country. :thumbsup:
larry

 

[crazyal]

Technically the tire is also a spring.

 

[SPYDERLK]

Technically the tire is also a spring.

Yes, but note that it has a very hi rate and getting higher as they are going to the extreme low profile tires on newer vehicles.
larry