The pump is probably the most important part of any pressure washer -- after all, without a functioning pump, a pressure washer is little more than an expensive water tank. However, a number of pump varieties are used to power pressure washers, and checking the manufacturer's specifications on what type a pressure washer uses is one of the most important things you should do before purchasing; each type of pump has its own individual characteristics, pros and cons.
These powerful pumps use a series of three pistons (similar to those found in a car engine) to pump water and are generally considered to be the gold standard for pressure washer pumps. They are robustly built, with stationary seals and a minimum of moving parts to provide a long working life with minimal maintenance and repairs required. Triplex pumps are also among the most powerful pumps you can buy and are excellent for heavy-duty commercial pressure washing -- despite this, the triple piston setup means that they run at a relatively slow rate, decreasing heat runoff and using less power.
As you can imagine, there is a price to pay for this high performance, and triplex pumps are generally the most expensive types of pumps on offer. As such, they are usually only fitted to large-scale pressure washers intended for commercial use and may be out of the price range of non-business buyers. The robust construction of a triplex pump also makes it very heavy, and a triplex pressure washer will usually need castors or wheels to move effectively.
Wobble plate pumps
These amusingly-named pumps also use pistons to drive water through the washer, but instead of conventional piston rods, the pistons in a wobble plate pump are compressed using an angled, rotating plate that compresses each piston in sequence. They are generally used in inexpensive pressure washers intended for home use, and as such, they inhabit the opposite end of the price range to triplex pumps. However, they can produce excellent pressure despite their low price. In addition, they do not require priming and can be run dry for brief periods without causing internal damage.
Unfortunately, the rotating wobble plate is not as efficient at compressing pistons as piston rods, and you may find that wobble plate pumps provide disappointing flow rates even at high pressures. Wobble plate pumps are also manufactured to specific tolerances and are very difficult to repair or adjust; a broken or malfunctioning wobble plate pump will generally have to be replaced.
Axial cam pumps
These types of pumps also rely on a rotating plate to provide pressure and flow. However, in an axial cam pump, the pistons are attached directly to the rotating plate and are emptied and filled by moving against a stationary, angled plate which provides positive and negative pressure as the pistons rotate. These pumps provide an excellent combination of pressure and flow rate and can be expected to last significantly longer than wobble plate pumps before needing replacement. They are also self-priming and can be more effectively repaired than triplex or wobble plate pumps due to their relatively simple design.
However, axial cam pumps need to run at relatively high rates to provide adequate pressure, and this high rate of revolutions can cause significant heat buildup, as well as gradually wearing away at the angled swash plate. As such, washers fitted with axial cam pumps tend to be heavily built, and may be fitted with cooling systems that further increase the weight of the washer. The high rate of piston rotation can also create excessive noise and vibration, particularly in aging washers.
For more information, contact Jetwave Industrial Equipment or a similar company.