Intellisteer Europe

Patently Better - An Independent Comparison

An important consideration when choosing a Hydraulic Linear Drive for use with a sailboat is the efficiency of the pump unit. An independent comparison by the University of British Columbia between piston pump and gear pump technology was undertaken during the first few years of manufacture of the patented piston design reversing pump from Octopus.

The extract below is taken from the independent report by the University of British Columbia:
 
Gear pumps employ a minimum of two rotating gears in mesh which forces the oil to travel... and are quite complicated as a check valve is required to monitor the flow of oil.

Also, as the operating pressure increases, oil will leak through the gears due to the necessary gap between the gear and its housing decreasing the volumetric flow rate.   The inefficiency is due to the action of the check valve mechanism and the gear leakage which occurs.

The Octopus pump operates on a patented moving piston principle, there are several advantages of this type of pump:

1. There are only three moving parts, increasing reliability.
2. It does not require a check valve, thus increasing efficiency.
3. Pump flow rate is adjustable and so set for the vessel it is on.

The evaluation showed that a piston pump was three times more efficient than a gear pump.  These findings are still true today - an Octopus Linear Drive can be expected to halve the battery consumption when compared to a competitor’s unit, therefore doubling the effective range of the autopilot on one battery charge. The graph shows actual test performance of an Octopus Pump compared with an inefficient gear unit.

We have a full range of powerful, low current consumption hydraulic Linear drives that are designed for long passage making. These drives are built for maximum performance.  The drives are available in two styles either with the pump mounted on the cylinder or with the pump mounted separately.

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