Types and Features of Motor Pumps
In addition to GPM and PSI, your choice of the pump also matters. Below are common differences and options for pressure washers.
Triplex, Oscillating or Axial Pumps
There are three main pressure wash pump designs: axial, swing, and triplex design pumps. Axial and oscillating pumps are manufactured with fewer heavy components. Axial and oscillating pumps generally have fewer maintenance parts.
Swing pressure wash pumps are the most affordable. However, they are also considered to be the lightest wash pumps. You can generally expect an oscillating pressure washer pump to last 200-400 hours. Swing pumps are less efficient compared to other pumps because the pump has to work to overcome the water and two springs. Swing pumps are usually not repairable.
Axial flow pumps have improved design and longevity with greater flexibility in GPM output and PSI. Axial flow pumps are the standard for domestic to consumer-grade pumps. Axial pumps typically last 2-3 times longer than swing pumps, which means you can expect an extra 500 to 800 hours of use.
While axial flow pumps are better made than swing pumps, they still experience more friction than triplex-type pumps.
Triplex pumps are more sustainable than axial and oscillating pumps. They also offer maximum flexibility in terms of GPM output and PSI, allowing higher PSI and GPM configurations. They are also repairable. Triplex pumps can easily last 10 times longer than axial flow pumps. The triplex pump draws in and discharges water by driving the pistons through the crankshaft.
Something else to consider: Unloaders available on pressure washers
The unloader on the pressure washer allows you to have no pressure on the gun when you release the handle, when you release the trigger, the water is diverted through the unloader and circulated back to the pump, removing any pressure on the pressure washer gun .
There are many different unloader designs. An important feature that some pressure washers offer is an adjustable unloader. If you're considering the ability to reduce the pressure your washing machine uses, an adjustable unloader may be helpful, which can be important when trying to prevent damage to softer surfaces (if your pressure washer doesn't offer an adjustable unloader, there are some low-cost options that go after the pressure washer gun, but they're not always as effective.
There are also internal and external unloaders. The external unloader is placed after the pump, while the internal unloader is built into the pump. While the external discharger can be easily removed, repaired, or replaced, the internal discharger can require some effort to open the washer and service. External unloaders are best because unloaders often fail over time.