Re: Liquid Ballast vs. Iron Weights

Posted by Benjb in NE on July 29, 2004 at 09:10:18 from (68.118.144.78):

In Reply to: Liquid Ballast vs. Iron Weights posted by 720Deere on July 29, 2004 at 06:26:53:

The answer to your question involves Physics, moments of inertia, and Calculus, integration. The basic equation is I=MR^2. By knowing the different radii and the masses involed you can set up an intergal to evaluate between the two radii. If you do a general equation for a hollow cylinder (liquid ballast) and a solid cyclinder (wheel weight) you get I=.5M(R_1^2+R_2^2) and I=MR^2, respectively. By comparing the two I's you can see which one would have a greater inertia (resistance in a change of motion).

To illistrate, suppose you have a wheel with a 20 in minor radius and a 25 in major radius. You have the choice of putting a 1000# (treated as mass) wieght, with a 10in radius, or 1000# of fluid. The inertial for the weight would be .5*1000*10^2 or 50000 h's (arbitrary unit). The inertia for the fluid would be .5*1000*(20^2+25^2) or 512500 h's . The fluid in this example definitely has more inertia (about 10 times more) and would require more horse power. (to find the exact horse power difference you would need to get to standard units and plug into a few mor equations).

Another point to consider is that the fluid doesnt fill the entire tire. My Allis B manual said that originally they came filled with only 75% fluid. that means that the weight is not balance with respect to the axis of rotation. Which is easy to turn and keep turning, a balance flywheel or one with a large chunk taken out.
In both regards it appears that the solid wheel weights require less HP in order to move the machine forward

P.S. The closer the mass is to the axis of rotation, the less rotational inertial it has.

Follow Ups:

• Re: Liquid Ballast vs. Iron Weights Ron 09:37:26 07/29/04 (4)
  • Re: Liquid Ballast vs. Iron Weights G-MAN 10:55:51 07/29/04 (3)
    • Re: Liquid Ballast vs. Iron Weights buickanddeere 12:10:23 07/29/04 (2)
      • Re: Liquid Ballast vs. Iron Weights G-MAN 13:47:39 07/29/04 (1)
        • Re: Liquid Ballast vs. Iron Weights buickanddeere 08:33:05 07/30/04 (0)

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