Many people think pressure is created by the pump. But lets think about this.
If we take a pump that moves one gallon per minute (1 GPM) and connect a one inch (1") diameter hose that is one foot (1') in length from its outlet, and we install a pressure gauge at the end of the hose, should we expect to see any noticeable pressure reading on the gauge?
No, there is no pressure on the gauge. This is not because of a problem with the pump. If the pump is filling one gallon per minute, then the pump is working fine. There was no pressure because there was no resistance to flow.
Pressure is caused by resistance to flow.
So what resists flow? Hoses or pipes that are too small resist flow.
Elbows in the pipe will also cause more resistance, creating more pressure near the pump.
In hydraulics, resistance to flow mainly occurs as hydraulic fluid tries to flow through heavily loaded actuators.
A heavily loaded actuator could be a hydraulic motor trying to move a heavy material along a conveyor belt in a mine, or a cylinder trying to lift the boom on a crane.
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