Hydraulic pump redesign sees higher performance

The critical feature of the all new HPR-02 Variable Pump Series from Linde Hydraulics is the unique 21 degree swash angle, which enables much greater swept volumes to be achieved

The critical feature of the all new HPR-02 Variable Pump Series from Linde Hydraulics is the unique 21 degree swash angle, which enables much greater swept volumes to be achieved than on normal 18 degree swash angle pumps, all without sacrificing quality or service life.

The radical design of the HPR-02 embraces a whole new concept that sees prices below those of earlier series by between 5% and 20%, dependent on final specification.

This has been achieved by considerable investment in dedicated machine tools and improved manufacturing techniques which also give higher volumetric and mechanical efficiencies.

Designed for open loop applications, the new pumps result from an innovative rethink of the basic in-line axial piston, swash plate rotating group.

Traditional design swash plate pumps incorporate a ball on the piston end which locates into a socket on the slipper pad.

By placing the ball end on the slipper pad instead it can now go inside the piston which reduces overall unit length.

This new arrangement enables the critical increase from 18 degrees to 21 degrees for the swash angle, a change which is entirely responsible for the twin benefits of increased swept volumes and higher power density.

Further underlining the cost saving approach was the decision to deploy common rotating groups in both the pumps and motors plus the use of common parts in units of differing capacity.

The new wHisPeRing-02 derivatives of the standard HPR-02 series have been specially developed for systems where lower noise levels are particularly important.

Noise in static industrial systems, marine applications and mobile vehicles can be caused by many factors, not all of which are hydraulic.

Where airborne noise is partly produced by a hydraulic installation, it will have a pump at its origin.

Airborne noise can also be radiated by structures and can be excited by a prime mover such as an hydraulic pump, an electric motor or perhaps a diesel engine to such an extent that it is audibly intrusive.

When this happens there is an increasing number of mandatory Health and Safety considerations to be taken into account.

To address these issues, Linde development engineers set out to analyse and reduce the exciting frequencies and their amplitude generated by hydraulic pumps.

Detailed analysis of the pressure ripples within the -02 series HPR pump range enabled Linde engineers to significantly reduce the amplitude of the pressure ripples over a wide range of input speeds and operating system pressures.

Typically, sound level reductions of 2 to 4dB(A) have been achieved by reducing pressure pulsations from 38.7 bar to 11.3 bar.

The new units are available in 55, 75, 105, 135 and 210cm3/rev displacement and, while rated at 420 bar, are suitable for maximum a 500 bar.

The Linde Lintronic OCA (Open Current Amplifier) digital controller is specifically designed for use with Linde's HPR-02 series of power regulated, open circuit pumps which, in addition to either electric motor or diesel engine power limiting, incorporates a secondary feature that provides for direct control of pump delivery, down to zero flow, at pressure.

Tony Clements, Sales and Marketing Manager of Linde Hydraulics pointed out.

"The rotating groups used in the HPR-02 series have been operational for six years in other series, so the engineering and technology are well proven.

The design objectives were all realised which has resulted in an extremely compact unit with a high power density, improved efficiency, very low noise characteristics and at the same time, lower prices!".

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