On electric vehicles, low noise is a key requirement, while low-speed operation enables improved control and positioning for various vehicle functions. This means that gear pumps which can operate efficiently and quietly at low speeds are among the most important priorities for electric vehicle designers. CALMA technology is also attractive in other markets, including truck, bus and off-highway, where the trend towards lower noise standards has been further encouraged by worldwide legislation.
Following an exhaustive programme of research and development in collaboration with the University of Dresden, we developed a range of CALMA pumps in displacements from 6cc to 24cc. The company established itself as a leader in low-noise gear products a decade ago when it introduced the first WQ series (quiet) gear pump product line. WQ introduced the concept of true dual flank engagement of the gear teeth (as opposed to “near dual flank engagement”), which is unique to Concentric and which reduces the amplitude of the pressure pulsations introduced into the hydraulic system. CALMA is a significant step forward in low noise technology in that it reduces noise by up to 10 dB or 85% in low-speed applications. Low speeds at high pressure are the most severe condition for gear pump technology. The pump, features innovative tooth geometry, true dual-flank gear engagement, reduced trapped oil volume and advanced trapped oil management. The design reduces pressure pulsation by 75%, which is the key factor determining the pump's noise levels, while also reducing energy consumption.
Both static and in-vehicle tests have demonstrated that CALMA series pumps offer significantly lower noise operation when compared with other external gear pumps. In many cases, they can also match or even out-perform more expensive internal gear pumps on efficiency and low-noise operation.
CALMA is especially well suited to applications on electric counterbalanced lift trucks and warehouse lift trucks. Sound power testing in comparison with other quiet gear pumps on these vehicles showed CALMA provided significant reductions in noise during the steer, tilt and lift functions by 50% to 85%. CALMA is also well suited to electric aerial work platforms and other mobile equipment where low noise, low speed and high efficiency are required.