Diesel exhaust and noise pollution is an increasing concern for businesses but it has been a longstanding issue for the agricultural sector. 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, has developed the 1160 eHoftrac yard loader and this incorporates Bosch Rexroth's new generation of Silence Plus external gear pumps that reduce noise levels for work hydraulics so that mobile machines with electrical drives and hydraulic equipment can function as quietly as possible.
A well-known zoo in Copenhagen was one of the first users to trial the 1160 eHoftrac in day-to-day operation. Animal enclosures are just one example of 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 powers the Silence Plus external gear pump. This separation of functions improves energy efficiency of the vehicle, which is reflected in more operating time per charging cycle. The travel drive only requires electricity when the yard loader is being driven, and the same applies to the hydraulic pump, which is driven by its electric motor only when hydraulic pressure is required. The variable-speed motor control also ensures both motors always operate at the appropriate speed, which further helps to minimise energy consumption.
On average, the battery lasts for two to five hours, depending on the operating conditions and energy demand. Additional savings in operating costs can be made in future when buildings have photo-voltaic systems installed.
A beneficial aspect of the lower noise emissions, particularly for the agricultural market, is that the machinery can be used at any time of day. The machine's quiet and exhaust-free operation means 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.
Improved perception, quicker reaction times
The combination of electric drives and quiet, independently driven hydraulics increases 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, so the hydraulic pump blends in with the quiet operating sounds of the travel drive.
Traditionally, external gear pumps have been robust units for pressures of up to 280bar. With a number of structural improvements, Bosch Rexroth was able to reduce the noise emissions by up to 15dbA when compared with conventional pumps. One reason for the quiet operation is the angular tooth profile that prevents compressed oil entrapment and subsequently eliminates vibrations.
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 improved sustainability, but this technology also has positive effects on the health of both employees and animals.
With Silence Plus, Rexroth has developed a hydraulic pump that is well suited for use with electric vehicle applications thanks to its efficiency and low noise. As discussed above, 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, forklift trucks and buses.
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, which facilitates easy retrofitting.
Follow the link for more information about the Silence Plus external gear pump.