The term pilot ratio refers to the ratio of two, discrete areas of a piston, spool or poppet on which opposing pressures act. The pilot area, on which pilot-pressure acts, is always the larger of the two areas. Working or system pressure acts on the smaller, opposing area. This means a relatively small pilot pressure can overcome a much larger … Read more
Tag Archives: hydraulics design
The Official Word On Hydraulic Pump Suction Strainers
While doing some fact checking for a consulting job, I had cause to review Australian Standard AS 2671; Hydraulic Fluid Power-General Requirements for Systems. This Australian Standard is basically the International Standard, ISO 4413 with some amendments based on the local advisory committee’s input.
One of these amendments has to do with pump suction strainers. Section 8.3.3 of ISO 4413:2010, … Read more
Why a Hydraulic Pump Should Never Be Completely Unloaded
One of the advantages of variable-displacement pumps with hydraulic or electro-hydraulic displacement control, or load-sensing control, is their low standby pressure. Meaning, when pump output isn’t required, the pump ‘stands by’ at a relatively low pressure, and usually at zero flow — other than that necessary for the make-up of internal leakage.
From an efficiency (heat-load) perspective, the lower this … Read more