WASHER 8W7879 - Caterpillar

Illustration 1 g06054683
Eccentric Weights
(1) Eccentric weights
(2) Shot
(3) Drum motor
(4) Coupling shaft
(5) Vibratory motorThe drum assembly contains two eccentric weights (1). Each of these weights is located inside a housing. The eccentric weights are connected to individual splined shafts. The vibratory motor is splined to the shaft of the right eccentric weight. The shafts of the right and left eccentric weights are connected by coupling shaft (4).When the vibratory system is operating, vibratory motor (5) rotates eccentric weights (1) by rotating the splined shafts. The center of gravity of the eccentric weights is not at the center of the shafts. Therefore, rotation of the eccentric weights causes the drum to vibrate.On standard machines, the speed of vibratory motor (5) is fixed, and therefore, the frequency of vibration is fixed. On machines which are equipped with the optional vibratory system, the speed of the vibratory motor can be varied. Therefore, the frequency of vibration can be changed. While vibratory frequency depends on the speed of rotation, the amplitude of the vibration depends on the direction of rotation of the eccentric weights. Both vibratory systems can produce two amplitude levels.Internally, each eccentric weight (1) has a hollow pocket. The pocket is partially filled with shot (2). When the vibratory system is operating at low amplitude, the vibratory motor rotates the eccentric weights counterclockwise. This direction of rotation captures the shot in the pocket on the "light" side of the eccentric weights. This action brings the center of gravity of the weights closer to the center of the splined shafts, reducing the amplitude of the vibration.When the vibratory system is operating at high-amplitude, vibratory motor (5) rotates the shafts clockwise. In this case, shot (2) is captured in the pocket on the "heavy" side of eccentric weights (1). This action takes the center of gravity of the weights farther from the center of the splined shafts, increasing the amplitude of the vibration.