A "Direct Drive" pump has a hollow shaft, which simply slides onto the drive shaft of a motor or engine.
The flange on the pump is mounted to the face of the engine or shaft end of the motor. Normal gasoline
engine speed is about 3450 RPM. Since the pump is connected directly to the engine shaft, the pump RPM
is the same as the engine RPM. Electric motors typically will turn a direct drive pump at 3450 RPM or
1725 RPM. Direct drive pumps allow for a more compact designed pressure washer. Another advantage is
that this drive system is simple, with fewer moving parts; therefore less expensive. The disadvantage
is by having the pump spin as much as the engine or motor, the bearings and other parts get more wear
and tear, reducing the life span of the pump. Direct drive pressure washers transfer the vibration of
the engine or motor directly to the pump. Also, the faster pumps of direct drive pressure washers are
spinning so fast that they cannot draw water from a tank very well. However, they tend to work just
fine when the water is forced into the pump, like when it is hooked-up to a hose.
Benefits of Direct Drive:
Disadvantages of Direct Drive:
A "Belt Drive" pump has a pulley mounted to its solid shaft and is driven by one or more
belts that are attached to a pulley on the motor or engine. The pulley system allows these pumps
to turn at a much lower RPM than a direct drive pump (typically 900-1400 RPM). The belt drive pump
crankcase has a larger oil capacity. This, combined with the lower RPM of the belt drive pump,
allows the pump to run much cooler than a direct drive pump. The pump is isolated from the heat
of the engine or motor, also. Belts and pulleys also absorb vibration, reducing pump fatigue.
Because of these factors, most heavy use pressure washer applications will demand a belt drive pump.
The disadvantage of this system is there is some loss of efficiency due to the additional friction
from the belts and pulleys. Plus maintenance is required occasionally to adjust the belts. However,
all other things being equal, the belt drive system should provide for the longest pump life.
Benefits of Belt Drive
Disadvantages of Belt Drive: