Silence is golden: New development in low-noise gear pumps for mobile applications
Diesel exhaust and noise pollution is an increasing concern for businesses, but for the agricultural sector it has always been an issue. Hydraulic systems have many applications and benefits, but few people would associate their use with a quiet working environment, until now.
Agricultural machinery company, Weidemann, offers a solution in the form of its new 1160 eHoftrac®. The 1160 eHoftrac® is fitted with Bosch Rexroth’s new generation of external gear pumps, SILENCE PLUS, which reduce noise level for work hydraulics, so that mobile machines with electrical drives can function as quietly as possible.
A well-known zoo in Copenhagen was one of the first businesses to trial the 1160 eHoftrac® in day-to-day business. Animal enclosures are just one example where quiet and exhaust-free machines can be utilised effectively.
The 1160 eHoftrac® yard loader has two electric motors – one serves as the travel drive, while the second drives the SILENCE PLUS external gear pump. This improves energy efficiency of the vehicle, which is reflected in more operating time per loading cycle.
The travel drive only requires electricity when the yard loader is being driven. The same applies to the hydraulic pump, which is powered by the electric motor when hydraulic pressure is required. The variable motor speed control ensures both motors are always operating with the appropriate RPM, which helps minimise energy consumption.
On average, the battery lasts for two to five hours, dependent on operating conditions and energy turnover. Additional savings in operating costs can be made in future when buildings have photo-voltaic systems installed.
Longer utilisation periods
A beneficial aspect, particularly for the agricultural market, is that it can be used during any time of day. The machine’s quiet and exhaust-free operation mean employees no longer need to restrict themselves to narrow time windows in the morning and evening. Consequently, work can be spread out throughout the day without causing disturbance.
The combination of electric drives and quiet, independently driven hydraulics increase productivity, while drivers benefit from improved perception and quicker reaction times.
The SILENCE PLUS external gear pump, works quietly and also generates a frequency similar to that of an electric motor, and the hydraulic pump blends in with the quiet operating sounds of the travel drive.
Traditionally, external gear pumps have been robust units for pressure of up to 280 bar. With a number of structural improvements, Bosch Rexroth was able to reduce the noise emissions by up to 15 dbA when compared to conventional pumps. One reason for the quiet operation is the angular tooth profile which prevents compressed oil entrapment and subsequently eliminates vibrations.
Protection for health and the environment
With regards to sustainability, the electric drive’s batteries can be charged using electrical power generated on-site with photo-voltaic systems, biomass or wind. Not only does this contribute to a more sustainable climate but, this technology also has positive effects on the health of both employees and animals.
With SILENCE PLUS, Rexroth has developed a hydraulic pump which is well suited for use with electronic vehicle applications thanks to its efficiency and low noise emissions. As discussed, the 1160 eHoftrac® is a great application for use in a zoo, but it also finds use on dairy farms, horse stables and at animal husbandry businesses, in the hotel business or even in cemeteries. It is also listed for use in tractors, forklifts and buses in the mobile sector.
The low noise of the machine itself makes it easier to attain legal limit values without expensive secondary measures for acoustic decoupling, damping or encapsulation. The SILENCE PLUS external gear pump is compatible with all other Rexroth pumps so facilitates trouble-free retrofitting.
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