The calculation must be made for the entire range, not just the power curve except for racing. These components never come to a complete halt while the crankshaft is rotating and never change direction. Place C1 with the upper edges exactly level in C2.
The process is then reversed, giving the weight of the opposite end. Very slowly submerge the rod in C 1 up to the marked centerline. The dynamic forces are far more important than suspected. Early Chrysler hemis only have six weights, which leaves the weakest center area with heavily eccentric weight.
The minor diameter is about 2. To weigh each end based on the geometric center: All crankshafts are balanced at the factory, but not to the same degree as would be required for racing, or even by a careful owner. Dynamic Factors; pressure acting as weight The behavior of the gas in the combustion chamber alters the effective apparent weight of the piston.
Of course, this is never true; however it makes analysis and comparison easier so please bear with me click either rod for a larger view. Each point would travel the circumference of the shape shown during one rotation of the crankshaft, arriving back at the top TDC each time.
Even though on paper the total of the balance weights is correct, the out-of-balance forces engine components are corrected by opposing forces balance weights as much as one foot away from them. I suspect that a separate factor should be applied to hybrid weight, since it follows a path determined by rod geometry rather than a pure shape or vector.
The adjustment is usually made by removing metal from the counterweight or cheek directly opposite the center of an imbalance caused by excess weight.
An additional eccentric weight is attached to the damper, flexplate, flywheel, etc. The center of gravity method assigns grams more to the bob weight total: There are several possible reasons. Therefore, the absolute length of the rod as well as the rod ratio has an effect on balance.
Here is a rod drawn as if the cross-section were of continuous thickness. This affects selection of balance factor.
If Archimedes was right, the water overflow volume is exactly equal to the volume of the submerged rod mass. Fill C 1 exactly to the top with clean water.
However, Mallory metal is extremely expensive. The total of course equals the exact weight of the rod. One method of correcting this, and converting an externally-balanced engine to internal balance, is to remove some metal from the counterweights, and substitute a cylindrical slug of a much heavier metal.
The following text briefly discusses some of these factors, and the changes they cause in apparent piston weight. Suspend the rod from the pin eye so that the beam is exactly vertical. If enough steel is removed and replaced with Mallory metal, the counterweights will now be sufficient to balance the components without added eccentric weight outside the engine block.
Weigh C 2, and subtract the empty weight. Pull acts on the rod and crankshaft assembly in the same way as the actual weight of the reciprocating components themselves, but not at the same time, not continuously, and varying in degree based on the construction and size of the engine and its operating conditions.
The beam closest to the rod journal see 5 has an minor diameter amplitude almost equal to the stroke length laterally, plus a major diameter equal to the stroke length - almost a perfect circle. There have been many formulae published to calculate the exact amount of adjustment to make to the crankshaft to compensate for these factors.
Click the picture for a larger view. Multiply by the specific gravity of steel approximately 7. Over-balancing and under-balancing This method has been recommended for high RPM engines.How engine balancing is affected by factors other than the components’ weights.Download