Pressure washer pump types

Understanding the Main Pressure Washer Pump Types

When you start searching for a pressure washer, one of the first things you’ll notice is that several different pressure washer pumps are available, each with its own benefits and drawbacks.

There are also different brands to consider, and you should know which type of pressure washer uses which pump so you can make an informed decision when you shop.

Generally speaking, two groups of positive displacement pumps called reciprocating use plungers, pistons, or diaphragms, and rotary pumps that use screws, lobes, vanes, or gears.

You can further divide this into free, slightly more concise categories: axial cam, wobble, and triplex plunger pumps. Each has benefits and drawbacks.

The common thread among these pumps is that your machine requires a pump that can produce a high-pressure stream of water with a lower flow than other pumping applications, like sump pumps.

The pump also has to be economical, compact, and light, and this handy guide will break down each pump so you can make an informed decision.

Pump Types for Pressure Washers

We mentioned that positive displacement pumps came in reciprocating and rotary categories earlier. Each pressure washer pump in the reciprocating pump category utilizes plungers or pistons to add energy to the water, and there are two big differences between the plunger and piston pump, including:

  • The piston-style pump uses a driveshaft attached to a wobble plate or swashplate to drive the pump’s function. The plunger-style pump utilizes a crankshaft.
  • The piston-style pump has a cylinder seal attached to the piston, which moves on each stroke. The plunger pump has a cylinder seal attached to the stationary point the piston moves through on each stroke.

When people start talking about pressure washer pumps, they usually refer to them in one of three categories. Axial cam and wobble pumps are directly driven using a driveshaft with pistons.

The triplex plunger-style pump is crank or camshaft-driven using plungers. Each type has benefits and drawbacks; we’ll examine each in more detail below.

Drive Shaft Driven Piston Pressure Washer Pump

There are two types of pressure washer pumps in this category, and you must know how each one works and which applications it is best for to ensure you get the correct one for your projects.

Axial Cam Pump

An axial cam pump is a mid-level choice with a higher gallon per minute (GPM) and pounds per square inch (PSI) reading.

The pistons on this pump will rotate around the swash plate as it runs, and the angle of the swash plate affects the piston’s stroke as they move from one side to get the water and to the other to push the water out. In turn, this pump can have a larger oil reservoir and bearings, extending the pump’s life.

This video will give you an in-depth look at how an axial cam-style water pressure pump works. If you pick this option, you’ll find it in a host of pressure washers that offer less than 3,500 PSI.


  • Compact and small design
  • Adjust the swashplate angle to adjust the water flow
  • Has a longer lifespan than a wobble-style pump


  • Runs at the same speed as the engine
  • More difficult to cool down with extended use
  • Rotating mass can result in vibrations unless you balance it properly


  • When you compare this option to a wobble-style pump, you get a much longer lifespan of 500 to 800 hours. This is two or three times more than a wobble pump’s lifespan.

Wobble Plate Pump

A wobble pump is a good choice if you’re after a more entry-level pressure washer pump. It connects a wobble plate directly to the driveshaft, pushing the pistons back and forth to create suction to pick up the water before pushing it back out.

Each piston has a large spring that allows the wobble plate to push up against it, which cuts the pump’s efficiency down to around 70%.

This type of pump has many smaller, intricate parts that are almost impossible to repair. If one of them were to go out, you would have to throw the whole pressure washer away and purchase a new one.

The following video will give you an idea of how this unit functions. These pumps generally feature a 2,500 PSI and 2.0 GPM or lower rating, so they’re light-duty machines.


  • Self-priming machine
  • Seals don’t move with the piston to reduce wear and tear
  • Can run dry without damage


  • Low flow rate
  • Several moving parts make fixing it almost impossible
  • Not economical to fix it if it breaks down


  • This product has the lowest lifespan of the three pump options and usually tops at 200 to 400 hours. So, if you use it less than three hours a week, it’ll fail within two or three years.

Another important point to consider with these pumps is whether they have variable or fixed displacement. In a variable displacement system, you can adjust the angle of your swash plate to vary your flow rate. You can’t do this on a fixed version, so you get one flow speed.

Main Pressure Washer Pump Types

Crankshaft-Driven Plunger Pump

The second broad category only has a single pump, but this is more of a commercial-grade option than for residential use. So, the price to purchase it and perform maintenance tends to go up, but it has a much longer lifespan.

Triplex Plunger Pump

Professional or commercial-grade pressure washer pumps use this system because they can run for thousands of hours before anything needs routine maintenance and offer an impressively high-pressure level.

They use connecting rods and a crankshaft to make the positive action pistons suck up the water and push it out each time the pistons finish a stroke, similar to a car engine’s setup. They run cooler, and they are almost 90% efficient.

With this pump, the pistons fall around 120 degrees apart, giving you a smoother flow over the crankshaft’s revolution. You’ll find this pump in pressure washers that offer over 3,000 PSI.


  • A stationary seal means less wear and tear
  • Lower operating speeds keep it running at cooler temperatures
  • Less prone to leaking at higher pressures


  • Higher cost to buy it
  • Maintenance can be expensive
  • Easy to damage items around the house


  • The lifespan of your pressure washer unit will depend on your maintenance routine, but it can usually exceed 10 times what an axial pump will do before breaking down. Pressure washer units have low maintenance costs because the easily accessible pump heads and easily replaceable valves can increase lifespan.

Additional Pressure Washer Pump Considerations

Another large consideration you want to keep in mind with this product is the unloader that comes with the unit.

This unloader allows zero pressure in your gun when you release the handle. When you release the trigger, the water diverts through the unloader and circulates back into the pump, killing the pressure in the gun.

There are several unloader designs to consider on your pressure washer, and one big feature some models have is an adjustable unloader.

If your unloader is adjustable, it’s a useful feature that reduces the pressure your machine uses to prevent damage to softer surfaces.

If the unit doesn’t have this feature, you can get lower-cost options with a pressure washer gun you can adjust. However, they’re not 100% effective, and you can still damage items.

There are also external and internal loaders to consider. An external loader is placed after your pump, while the internal option is built right into the pump.

It’s easy to remove an external unloader to replace or repair them, and internal options take more time and effort. Unloaders are one part that has a history of failing, so going for an external unloader may be a smart choice.

Brands That Create Pressure Washer Pumps

There are several popular brands of pressure washer pumps, but you have to remember that many companies don’t like to advertise what pump is actually in their pressure washers.

Instead, they like to say that it has an axial cam or triplex plunger pump in the description. Common brands include but are not limited to:

AAA Pressure Washer Pumps or FNA Group

FNA Group makes AAA Pumps for their pressure washer line and owns the Simpson Cleaning brand. Simpson is the only brand that uses these pumps, and they make triplex and axial cam-style pumps.

Annovi Reverberi Pressure Washer Pumps

This is an Italian manufacturer of pressure washer pumps, and they make electric motors using the Ravel brand, too. They make axial cam, wobble, and triplex plungers for BE, AR, Campbell Hausfeld, Briggs & Stratton, Kranzle, Generac, Pressure-Pro, and Mi-T-M.

CAT Pressure Washer Pumps

This company first introduced pumps in 1968, offering 700 PSI and 4 GPM. They then moved into the car wash niche in Europe and the United States, and Campbell Hausfeld, BE, Pressure-Pro, DeWalt, and Simpson all use these pumps.

Comet Pressure Washer Pumps

Comet is the distributor in the United States for Comet SpA Italian pumps. These pumps are used in cement plants and breweries, pressure washers, and oil fields, and Excell is a company that usually features them.

General Pressure Washer Pumps

This company is based in Minnesota, and it’s a very popular company in the vehicle wash and pressure washing industry due to its triplex plunger pumps. Easy-Kleen, DeWalt, and BE are three companies that commonly use these pumps in their machines.

Karcher Pressure Washer Pumps

This German company is one of the biggest manufacturers of pressure washer pumps in the world. They’ve designed pumps from the ground up using a corrosion-free material to make them last longer. Karcher is the only company that uses these pumps, and they make all three types of pumps for residential and commercial-grade machines.

Kranzle Pressure Washer Pumps

Kranzle is another German-founded and based company popular in the industrial vacuum, pressure washer, sweeper, and dust extractor industries. It makes all three types of pumps and is the only company that uses them.

How to Purchase Replacement Parts and Pressure Washer Pumps

If your pump fails, you can purchase a new pump or parts to fix your pressure washers at several places, like RepairClinic or Amazon.

You should note that the pump’s description will tell you almost everything you need to know about this pump, but you want to double-check that the drive shaft measurements match.

The motor or engine should also have enough power for the new pump, and it’ll have to be the correct configuration so you can mount it.

Bottom Line

When deciding which pressure washer pump is best for your needs, there are many things to consider. You now know how each works, its benefits and drawbacks, and the brands that manufacture and sell the pumps.

This guide can help you keep your machine running smoothly and tackle all your projects around your home or business.

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