ICE recently introduced its line of high speed variable moment vibros. The largest of the three models, the 50ZR (zero resonance), was just unveiled at Bauma 2013. Eastrock, ICE’s Canadian distributor, is pleased and excited to be able to offer these exciting products to the Canadian piling industry. Variable moment vibros provide a number of benefits and are being specified more and more on projects where the vibration created by traditional vibrator-extractors may introduce concerns. Complementing the variable moment with high speed functionality really makes the new ZR vibros “game changers” compared to standard vibratory drivers and extractors.
What is Variable Moment Technology?
Variable moment technology means the hammer produces no amplitude or moment (energy) when the hammer is started or stopped, and the output energy (moment) of the hammer can be adjusted from zero to full output during operation.
How is Variable Moment Achieved?
Variable moment output is accomplished with the use of two (or more) pairs of counter rotating eccentrics, one set opposing the other set during start up and shut down. The eccentric pairs are phased in and out of time with each other during operation creating variable levels of amplitude or moment (energy). By controlling the phase angle between the eccentric pairs, the hammer is able to operate at any moment from zero to full moment. When the eccentric pairs are 180 degrees out of phase, the hammer produces no moment and thus zero resonance.
Two major benefits of ICE’s ZR vibros are infinite amplitude control, and high speed operation. Infinite amplitude control gives the operator the ability to minimize the radial vibration in the surrounding native soil and maximizes the drivability of the pile all while limiting the impact on nearby structures. High-speed operation through functioning at higher vibrations per minute further reduces the extent of the surrounding soil vibration and results in a suppressor that produces virtually no crane line vibration (crane shake) which is common with a standard driver/extractor. The high-speed design also provides more frequencies in which the vibro can be operated compared to a standard vibro, with some units having a max frequency of 2300 VPM. This creates a larger window of opportunity for aligning the operating frequency which is optimal for the soil type.
The starting and stopping of standard drivers/extractors has the highest impact on the surrounding soil. During the time that a standard driver/extractor takes to accelerate to full speed, the amplitude of the soil vibration is many times larger than when the driver/extractor is at its full speed. The same is true for when it is shut down. This effect is known as resonant vibration, which is forced vibration in which the frequency of the disturbing force is very close to the natural frequency of the system, so that the amplitude of vibration is very large.
Vibration sensitive jobsites are the primary places variable moment drivers/extractors are beneficial and there are many examples of vibration sensitive sites. Some of these are when older foundations are in close proximity to the jobsite, when jobsites are close to seismically-sensitive businesses with sensitive equipment, construction sites near occupied buildings, construction during non-standard work hours, construction near medical clinics and hospitals, driving operations close to curing concrete, project sites near pipelines and utilities as well as operations around rivers and waterways with known fish spawning grounds.
Other benefits of the ICE ZR vibros are that crane shake is eliminated during starting and stopping, driving speed can be controllable by the operator, pile penetration rates are increased in non-cohesive soil conditions, and setting and starting a pile is made easier by starting with reduced moment.
ICE continuously works to refine and improve the functionality, durability, and reliability of the equipment they produce. A great deal of their understanding and expertise were incorporated into the ZR designs. With the pairs of eccentrics being aligned one above the other in the transmission case, ICE made the decision to wrap the suppressor housing around the transmission case in order to lower the overall profile of the ICE ZR series vibros, as well as to improve their centre of gravity. The computer controls on the power units reduce fuel consumption, pinpoint repair needs as well as provide diagnostics and logs. The power units have an open circuit system for maximum cooling and filtering efficiency, also variable displacement pumps for optimum power consumption and smooth operation. The power unit oil cooler is combined with the engine cooler providing ample capacity without using auxiliary power to drive extra cooler fans. The ZR units are adaptable for underwater, low headroom, or box leads operation.
If you have any questions or want more information regarding the exciting line of ICE ZR vibros please contact Eastrock today at 613-737-3963. Eastrock is your Canadian Impact Energy Specialist. We are a growing, customer focussed Ottawa-based company with a diversified product line of piling equipment, rotary heads, foundation, and geotechnical drills, rock drills, HDD drills, drilling consumables, and grouting systems.