A belt driven pressure washer is definitely higher quality and more reliable than a direct driven pressure washer. The reason they are better is that there is less heat transfer from the engine to the pump resulting in less wear and tear on the pump's seals. Heat is the number-one killer of seals in a pump. Also, on belt driven models, the pumps run on a gear reduction pulley system. This means that the engine will run at 3600 RPM’s but the pump will spin at 1800 RPM’s.
Overall belt drive pressure washers are well worth the extra cost if you expect frequent use. These types of pressure washers can be used on a daily basis and still hold up over time. Also, when considering your application, if you plan to use the pressure washer for several hours at a time, there is no question you should purchase a belt driven washer!
Another benefit to the belt driven gas pressure washer is the ability to be
somewhat gravity fed. You can pull water from a height that is either equal or
higher than the pump's inlet. However, you cannot pull water from below the
pump's inlet with this pressure washer. This is beyond useful in mobile applications; direct drive pressure washers would require an inline water pump to supply
the unit with the required GPM.
Belt drive units do require new belts when
they begin to wear and stretch. A stretched belt will result in lower
performance, with lower PSI and GPM. There's no exact time
when the belts need to be replaced. It's determined by the use and the quality of the pressure washer. Generally, the
belts will last a few years.
With all of this being said, if you're a professional who will consistently use your pressure washer for several hours per day,
there's no reason to purchase anything but a belt drive pressure washer. In the long run it
will provide much greater service and lifespan than the direct drive units. Lastly, for the common homeowner who's not going to use the
machine every day, belt driven washers are unnecessary overkill. Direct driven units are
perfect for the weekend warrior. I wouldn't suggest a belt driven unless it's being used for professional applications!