All your paving equipment needs to be able adjust to specific application requirements, including the placement of thick or thin lifts. That includes asphalt compactors, which increasingly must handle thinner lifts and the amplitude and frequency settings that go with them.
The need for a single roller to properly compact both thick and thin lifts is the reason Caterpillar developed the Versa-Vibe™ Vibratory System. The system handles a wide range of compaction equipment requirements in both high amplitude/low frequency, or in low amplitude/high frequency settings. Simply put, the system enables a single machine to perform at high speeds on thin lifts and overlays, or at low speeds on thick lifts and coarse mixes.
That versatility has key advantages, including cost savings. In fact, the Versa-Vibe System creates such versatility that one asphalt compactor can accomplish what otherwise would require two very different machines.
Productivity. With asphalt compaction, productivity can be measured as the number of passes required to reach a target density. That number depends on the stiffness of the mix and the weight and drum movement of the vibratory compactor. Mixes that pass beneath the screed at more than 87 percent of theoretical density might only require a “typical” compactor.
However, Versa-Vibe compactors have a significant production advantage over typical rollers when the mix is stiffer. The Versa-Vibe machine will achieve target densities in fewer passes because of its dual vibratory drum/higher amplitude compaction. Job studies verify that tough compaction applications need dual vibrating drums with high amplitude. In certain applications, high frequency and high rolling speeds can increase productivity by as much as 50 percent over traditional compaction methods.
Versatility. Some competitive rollers have lower amplitudes in their single vibratory drum, yet they have no high-frequency option. At best, some have medium frequency (3,000 vibrations per minute) in the vibratory drum and 2,500 vpm in the oscillatory drum. This makes the rollers ineffective on high-production, thin lift projects. With these rollers, compaction sometimes can’t be achieved. Worse, the mat can be damaged if it has cooled considerably before the compactor is able to reach it. A lower-frequency roller also can leave impact marks in the surface of thinner mats if traveling faster than the vibratory system will allow in regard to impact spacing.
Simplicity. Cat® Asphalt Compactors offer straightforward vibratory choices that are easy to implement. It starts when the operator selects either “light” or “heavy” amplitude with the handwheel. Next, with the flip of a switch, the operator selects the “low” frequency option of 42 Hz or the “high” frequency option of 63.3 Hz. The operator can switch between high amplitude or high frequency while the machine is operating.
With some other rollers, the vibratory and oscillating drums have different variable frequencies—yet only a single frequency gauge. That means the amplitude changes only as the operator adjusts frequency. The result: The roller never properly matches the job’s demands. In addition, operators find this system difficult to understand and therefore seldom make the proper adjustments. (See the sidebar for an explanation of how Versa-Vibe works.)
Maintenance. The Versa-Vibe System is virtually maintenance-free with a 3,000-hour/3 year maintenance interval. Other systems typically feature two belt-driven weight shafts that require maintenance every 1,000 hours.
Rollers with Versa-Vibe feature all the other benefits you’ve come to expect from Cat products, including the unparalleled customer support and parts availability. Call your Cat Dealer for more information about the benefits of Versa-Vibe, including replacing two application-specific compactors with one fully adjustable machine.
The foundation of the patented Versa-Vibe™ Vibratory System is similar to the standard vibratory system: The rotation of an unbalanced weight shaft provides drum movement, or amplitude. However, on the Versa-Vibe System, a fixed eccentric weight is coupled to a two-position counterweight partially filled with steel shot.
By using the hand wheel on the side of the drum, the operator selects “H” to set the counterweight in a more eccentric position for higher amplitude or “L” to set the counterweight in a more balanced position for lower amplitude.
When the operator selects high frequency, the weight shaft spins in a clockwise direction, the steel shot in the hollow weight are confined adjacent to the eccentric weight, and the lower amplitude is created. When the operator switches to low frequency, the weight turns counterclockwise, the steel shot are moved to counterbalance the eccentric weight, and higher amplitudes are automatically created.
In total, there are four amplitudes and two vibratory frequencies.