By Josh Cosford, Contributing Editor
The type of pump you choose for your power unit affects the nature of the HPU build. Pump choice boils down to cost, complexity and performance. There are three major types of pumps: the gear pump, the vane pump and the piston pump. There are other, less common pumps, but we’ll stick to these three for this discussion.
Gear pumps are economical, but on the low end of the efficiency range. They’re reliable and durable, but efficiency tends to drop over time. Remember, a pump’s job is to convert incoming mechanical energy into hydraulic energy, and the more efficiently it does so not only allows you to choose a smaller motor, but more efficiency saves you money over time. Traditional spur gear pumps average about 80% efficiency, meaning your 10 input horsepower will net you 8 hydraulic horsepower.
Gear pump advantages: economical, reliable, easy to install
Gear pump disadvantages: inefficient, noisy
Vane pumps reside in the middle ground between gear and piston pumps. They’re more efficient than gear pumps, but less so than piston pumps. Vane pumps are quiet, making them popular for industrial applications. They’re also available with myriad control options, such as pressure compensation, load sensing and displacement control. Vane pumps typically cannot handle high-pressure circuits, however.
Vane pump advantages: quiet, moderately efficient, many control options
Vane pump disadvantages: low pressure
Piston pumps take up the premium end of the range. They’re capable of very high pressure, and have nearly infinite methods of control, including pressure compensation, load sensing, servo control, horsepower control, etc. They’re also very efficient; some designs are capable of 95% efficiency, allowing you to get the most from your prime mover. Their downside is cost, both for initial investment, and for service and repair.
Piston pump advantages: efficient, high pressure, many control options
Piston pump disadvantages: costly, complex, noisy