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| Illustration 1 | g06608550 |
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Vibratory Pod for Two-amplitude System (1) Shaft bearings (2) Eccentric weight (3) High amplitude operation (4) Sight gauge (5) Indicator (6) Eccentric weight housing (7) Output shaft (vibratory motor) (8) Low amplitude operation | |
Each drum assembly contains one eccentric weight (2). The vibratory motor drives the eccentric weight through output shaft (7).
When the vibratory system is operating, the vibratory motor rotates eccentric weight (2). Since the center of gravity of the eccentric weights is not at the center of the shaft, rotation of the eccentric weight causes the drum to vibrate.
Eccentric weight (2) is partially filled with shot. When the vibratory system is operating at low amplitude (8), the motor rotates output shaft (7) so that the shot is captured in the pocket on the "light" side of the eccentric weight. This action brings the center of gravity of the weight closer to the center of the output shaft, reducing the amplitude of the vibration.
When the vibratory system is operating at high amplitude (3), the motor rotates output shaft (7) so that the shot is captured in the pocket on the "heavy" side of eccentric weight (2). This action takes the center of gravity of the weight farther from the center of the splined shaft, increasing the amplitude of the vibration.
Rotation of eccentric weight (2) places shaft bearings (1) under a high load. This load creates the need for constant lubrication. The bearings are splash lubricated with oil inside eccentric weight housing (6). The housing contains sight gauge (4) to indicate the oil level. This gauge is on the opposite side of the drum as the vibratory motor. To check the oil level, the drum must be rotated until indicator (5) is in the lowest position. At this point, oil should be visible across the midpoint of the sight gauge.
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To prevent damage to vibratory system components, do not operate the vibratory system for more than 5 minutes without rotating the drum. |
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| Illustration 2 | g06608798 |
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Vibratory Pod for Versa Vibe System (9) Shaft bearings (10) Eccentric weight (outer) (11) Eccentric weight (inner) (12) Output shaft (13) Amplitude selection wheel (14) Sight gauge (15) Indicator (16) Spring and coupling (17) Eccentric weight housing | |
Each drum on the machine with the Versa Vibe system contains two eccentric weights (10) and (11) and amplitude selection wheel (13). One of the eccentric weights is inside the other weight.
Outside eccentric weight (10) is a fixed weight. Inside eccentric weight (11) is partially filled with shot. Amplitude selection wheel (13) can be used to change the position of the inside eccentric weight relative to the position of the outside eccentric weight.
Eccentric weights (10) and (11) are in eccentric weight housing (17). The housing is inside the drum. The weights are connected to output shaft (12) of the vibratory motor. When the vibratory system is operating, the output shaft from the vibratory motor rotates the two weights. Since the center of gravity of the eccentric weights is not at the center of the output shaft, rotation of the eccentric weights causes the drum to vibrate.
On machines with the Versa Vibe system, two eccentric weights (10) and (11) are mechanically interlocked and held in place by spring and coupling (16). The orientation of the weights, relative to each other, and the direction of rotation determine the vibratory amplitude.
Amplitude selection wheel (13) is connected to inside eccentric weight (11). This wheel is on the opposite side of the drum from the vibratory motor (on the same side as the propel motor). When the amplitude selection wheel is pulled out, the coupling between the two weights is released. This action allows the amplitude selection wheel to be rotated and the orientation of the inside weight (with respect to the outside weight) to be changed. When the wheel is returned to the locked position, the coupling is engaged and the weight is locked in position.
The amplitude of the Versa-Vibe system is determined by two settings. The first setting is the frequency, which in effect sets the direction of rotation of the weight set. This setting has the largest effect on the amplitude. Depending on the direction of operational rotation of weight set, the shot inside inner eccentric weight (11) will shift. This shift either increases or decreases imbalance mass relative to the fixed mass of outer eccentric weight (10).
The second setting is the position of inner eccentric weight (11) relative to outer eccentric weight (10). When the inner weight is in the"H" position, the highest amplitude will be obtained for the given frequency or direction of rotation. When the inner weight is in the"L" position, the lowest amplitude will be obtained for the given frequency or direction of rotation.
The two settings described above create four possible amplitudes: low, medium low, medium high, and high. When the vibratory frequency mode is set to high and amplitude selection wheel (13) is in the"L" position, the system operates in low amplitude. When the vibratory frequency mode is set to high and the amplitude selection wheel is in the"H" position, the system operates in medium low amplitude. When the vibratory frequency mode is set to low and the amplitude selection wheel is in the"L" position, the system operates in medium high amplitude. When the vibratory frequency mode is set to low and the amplitude selection wheel is in the"H" position, the system operates in high amplitude.
Note: The front and rear amplitude selection wheels must be set to the same amplitude during machine operation.
Rotation of eccentric weights (10) and (11) places shaft bearings (9) under a high load, creating the need for constant lubrication. The bearings are splash lubricated with oil inside eccentric weight housing (17). The housing contains sight gauge (14) to indicate the oil level. This gauge is on the same side of the drum as amplitude selection wheel (13). To check the oil level, the drum must be rotated until indicator (15) is in the lowest position. At this point, oil should be visible across the midpoint of the sight gauge.
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| Illustration 3 | g06608816 |
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Eccentric Weight Rotation (18) Convergent rotation (low amplitude) (19) Divergent rotation (high amplitude) | |
On machines with the two-amplitude and Versa Vibe vibratory systems, the rotational direction of the eccentric weights determines the amplitude of the system. The front and rear drums are mirror images. The rotational direction of the eccentric weights with respect to the input shaft must remain the same to create the same amplitude for each drum. Therefore, the eccentric weights must be rotated toward the center of the machine or away from the center of the machine.
Rotation toward the center of the machine is called"convergent rotation" (18). Rotation away from the center of the machine is called"divergent rotation" (19). Convergent rotation produces low amplitude. Divergent rotation produces high amplitude.
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| Illustration 4 | g06608857 |
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Vibratory Pod for Oscillatory System (20) Oscillatory pod (21) Shaft coupling (22) Output shaft (23) Vibratory motor (24) Power transmission (25) Belt drive | |
The oscillatory drum system is available as an option for rear drums. The oscillatory vibrator system contains two oscillatory pods (20) that contain rotating eccentric weights.
When the oscillatory vibratory system is operating, vibratory motor (23) rotates output shaft (22). Shaft coupling (21) transfers this rotation to power transmission (24). The power transmission uses belt drive (25) to synchronize the rotation of the weights in oscillatory pods (20).
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| Illustration 5 | g06608888 |
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Eccentric Weights in Oscillatory System (20) Oscillatory pod (24) Power transmission (26) Eccentric weight (27) Tangential force (28) Oscillatory motion (29) Eccentric weights inward (30) Eccentric weights outward | |
Oscillatory pods (20) are driven by power transmission (24) via belt drive (25). Each pod is mounted inside the drum in a position that places the center of gravity away from the center of rotation of the drum.
Each oscillatory pod (20) contains rotating eccentric weight (26), and functions in a manner similar to a vibratory pod on a conventional system. In the oscillatory system however, the eccentric weights are indexed to be in opposing positions as the eccentric weights rotate in each pod. During operation, the eccentric weights alternately rotate inward (29) toward each other, and then rotate outward (30) away from each other. During rotation, the opposing center of gravity of the eccentric weights forms a cyclic imbalance. This imbalance creates an oscillatory vibration.
The oscillatory pods are synchronized so that the oscillatory pods simultaneously impart alternating and opposing tangential forces (27) on opposite sides of the drum. These tangential forces produce a moment around the drum axle. This torque produces oscillatory motion (28) of the drum.
As oscillatory pods (20) operate, the oscillatory pods produce rapidly alternating tangential forces that cause the entire drum to oscillate, or vibrate back and forth along the same direction in which the drum is rolling.
With an oscillatory system, the drum remains in constant contact with the paving surface. The compaction energy is directed into the paving surface as a combination of the weight of the drum and the shear forces at the area of contact.