Parts Of A Pressure Washer

Motor (Gasoline, Diesel or Electric)

  • Pressure Pump
  • Pressure Hose
  • Trigger Gun
  • Unloader Valve
  • Pressure Wand or Lance
  • Wand or Lance Tip


Parts of a  pressure washerDifferent sorts of motors are used for different types of pressure washers. It may also depend on the type and location of the applications. Most high power washers used in industrial works, commonly use gasoline or diesel motors. Because most industrial cleaning requires great amount of time, these motors could run much longer without overheating compared to their electric counterpart. And since most industrial works are done outdoors; and sometimes or mostly offsite, where there are no available electricity. The ones with electric motors are mostly used for light to moderate washing works (e.g. house, car, and small boats) and are the most excellent used for indoor applications because these motors do not emit harmful fumes.


parts of a pressure washerYou’ve now arrived at the “core” of the system, the high pressure pump. All are positive displacement reciprocating pumps either piston or plunger types. Plunger pumps are the most efficient and have a longer life, therefore they are the most commonly employed pumps found on a quality power washer today.

There are duplex and triplex plunger pumps. Plungers are typically made of ceramic, a very hard material with excellent wear resistant characteristics. The triplex pump has become the most popular due to the smoother flow it creates.

These pumps are incredibly robust and virtually trouble free when properly maintained. Most people suspect the pump first when experiencing a problem but amazingly 90% of problems can be traced to causes other than the pump.


A high pressure hose is composed of an inner tube in which the water flows. This is wrapped in either a single or a double braid of wire mesh. This is in turn surrounded by a rubber outer cover. The cheaper hoses are covered in a thermoplastic material the better hoses have rubber covers. Most hoses are manufactured with burst ratings 4X their rated working pressure. When matching hoses to machines try to use a hose rated slightly higher than the psi rating of your machine. It will last longer. Typical psi ratings are 3000psi, 4000 psi, 4500 psi, 5000psi and 6,000 psi. 3,000 and 4,000 psi hoses are generally single braid while 5,000 psi and above are virtually always double braided (2-wire).


A good pressure washer hose is the same design principle as a hydraulic hose. The basic construction is as follows:

  1. Inner Core – This is the inner core in which the water actually flows.
  2. Wire Wrap – This is the wire wrapper that surrounds the inner core and protects it from damage. This wrap is in a braided configuration which allows the hose to bend freely while having ample protection. Most Hoses under 4500 psi ratings have single wire wraps and are referred to as “single wire or R-1″ hoses. Hoses designed for psi ratings of 5,000 or above and hoses designed for hot water use have two wire braids and are referred to as “2-wire or R-2″ hoses.
  3. Outer Cover – The best covers are rubber, thermoplastic covered hoses are widely used on pressure washers that are designed to be sold at a cheap price. If quality is important to you I would be sceptical of machines that are sold with a thermoplastic hose as standard.

Exception: The most notable exception is in the case of sewer jetting. In this case the pressure washer is designed to unblock and clean sewer lines. For this application 1/4″ and 1/8″ thermoplastic hoses are an advantage due to their ability to make extreme bends within pipes.

The standard size for pressure washer hoses is 3/8″OD (outside diameter). This is because the vast majority of pressure washers are rated between 3-5 gallons per minute flow rates. If your system exceeds a flow rate of 5gpm or if you are planning on using more than 100′ of hose continuously then consider 1/2″OD hose. Many lesser pressure washers of dubious quality market pressure washers with 1/4″ thermoplastic covered hoses in 25′ lengths. For me this has always been a tipoff to investigate quality issues further prior to any purchase. Standard quality hoses come in 50 ft lengths.

TIP: If you are planning to use 100 ft or more hose continuously don’t buy a 100 ft hose, buy two or more 50-foot hoses and link them together as that way if a hose goes bad or wears out you can keep working and you don’t lose an extremely expensive hose.

A black or red rubber hose can leave marks on surfaces, this can be a concern when pressure washing roof tiles or when doing flat work on concrete. In these cases use blue or gray covers these do not leave marks or scuffs and are referred to as “non-marking hose”.

Yellow coverings are typically made so that the hose is more resistant to the effects of oil, grease, and animal fats these are often used in rendering plants and other industrial applications. If you are working at heights, remember that all the weight of the pressure washer hoses when filled with water can be pulling on the hose fitting.

The best manufacturers sell pressure washer hoses that are skived before coupling. Skiving means the outside rubber cover is partially removed to allow the metal fitting to be crimped to the wire braiding of the hose. This process provides a solid metal to metal solution with good strength.


Considering there are numerous styles of pressure washers, the appropriate trigger gun should complement the whole pressure washer to maximize it for best use and there are also different styles available to pressure washers today.

  • Pistol Style Guns
  • Straight-Through Guns
  • Front Entry Guns
  • Rear Entry Guns
  • Dump/ Weep guns
  • Open Guns

Trigger guns that stop the water flow are the most commonly used guns in power washer systems equipped with unloader valves. Front entry guns are common on the lesser priced units and rear entry guns are far and away the most popular. Rear entry guns do a better job of keeping the hose out of the operators’ way and are better balanced.

These guns control the water flow via a spring, ball and seat which are actuated by the trigger. When the trigger is released the ball is pressed against the seat by the spring and water, aided by a check valve in the outlet of the unloader. Water is “trapped” in the hose under pressure and the pump enters bypass mode.

With this setup you will experience some “kickback” when you squeeze the trigger so be careful when using ladders and other types of access equipment. Dump Guns and open guns are operated without unloader valves because they don’t stop water flow.

The standard pressure washer trigger gun which almost every manufacturer supplies, either a front or rear style pistol gun which stops the flow of water and necessitates the need for an unloader valve. These guns have long been considered to be the industry the standard.


This is the main “safety” in your power washer system. The most commonly used is the “pressure actuated” type valve. When the pressure gun trigger is released the valve senses the pressure build up and like a “traffic cop” it diverts the water flow from the pump outlet back into the inlet side of the pump this is called “bypass mode.” Without this critical component this closed-gun situation would build pressure to the point where it would stall the power source, rupture the gun, hose or even the pump itself.


These simple seemingly insignificant components are what make the whole high pressure system work. Pressure washer nozzles contain a small orifice which is sized to create the desired pressure at a specific flow. This orifice is a restriction in the water flow. When the flow from the pump is forced through this restriction pressure is created. It is only now that you have a pressure washing system. Pressure washer nozzles with an orifice that is most closely sized to the specs of your pump will give you the optimum performance. The high pressure nozzle is a much more important component to the power washer than most realize. This creates the restriction that allows the water flow to become “pressurized” and delivered with such force. A worn nozzle will reduce pressure noticeably. A mismatched orifice can have the same effect. A nozzle with little to no wear and one with an orifice properly sized to your pumps’ output will get the most performance from your machine.

This is the last post is from a series of six on

Everything You Ever Wanted To Know About Pressure Washing.

Part One : What Is A Pressure Washer

Part Two : How Does The High Pressure Washing Work

Part Three : What Can A Pressure Washer Used For?

Part Four : How To Use A Pressure Washer

Part Five : What Are The Different Types Of Pressure Washer

Part Six : Parts Of A Pressure Washer

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6 thoughts on “Parts Of A Pressure Washer

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  3. we have a ryobi pump model ajp1600 i want to know that who is the sole agency in united arab emirates (U.A.E.)and from which place i can get the spareparts for that . Can u please send the details in my email adress.

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