Intensifier pumps are called intensifiers because they use the concept of pressure intensification or amplification to generate the desired water pressure.

If you apply pressure to one side of a cylinder and the other side of the cylinder is the same surface area, the pressure on the other side will be the same. If the surface area of the smaller side is half, then the pressure on that side will be doubled. Generally with intensifier pumps there is a 20 times difference between the large surface area (where the oil pressure is applied) and the small surface area (where the water pressure is generated). The following picture shows this concept.

Ultimately, there must be a restriction in the flow of water in order for the pressure to be generated. This restriction is generated by the orifice in the cutting head. Pressure is maintained until the orifice diameter exceeds the limits for water output of the pump.

For very small diameter orifices, in order to maintain pressure, the pump only needs to cycle very slowly to maintain pressure. As the orifice gets larger, the pump must work faster to maintain pressure and water flow. If the orifice gets too large, the pump tries to cycle too fast for the design specification. An "over stroke" situation is sensed by the control and the pump is stopped with an error message.

If there are leaks in the water circuit between the pump and the cutting head, this can also result in a pump "over stroke" situation. The leaks effectively rob water available to go to the cutting head. The same as putting in too large of an orifice, the pump runs faster to maintain pressure until it reaches its limit.

Typically, intensifiers stroke at around 50 - 60 strokes per minute when working at full capacity.