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Why you should never dry start a hydraulic motor ben lee

Hydraulic motors and pumps, like all hydraulic equipment, need adequate lubrication to function properly.  A lack of lubrication causes moving parts to grind against each other, causing wear and tear and also generating heat – both things which cause severe yet preventable damage to the equipment.  Unfortunately, many people operating hydraulic machinery are unaware of the science behind it, and do not understand why dry starting a motor or pump is a bad idea, especially if they have been told that a motor or pump housing will fill with hydraulic oil during operation.  Of course, this will happen, but not immediately on starting – it can take several hours for a decent level of fluid to build up in the housing to protect and lubricate the machine, and in that time irreparable damage is occurring.  As Alexander Pope's famous misquote states, “A little knowledge is a dangerous thing” (the original quote was “a little learning is a dangerous thing” - for those who are interested).


This is one example of preventable damage that can be addressed through basic training.  By instructing pump operators to check the fluid levels prior to starting and explaining the dangers of not doing so it is possible to improve and build upon the knowledge the operators already have, which helps empower staff to learn more.  The simplest way to check is to remove the top-most connection on the pump or motor housing.  If oil comes out of the seal, then there is enough hydraulic fluid in there for the equipment to be started.  If no oil comes out, then the housing should be filled with the same hydraulic fluid that it uses to ensure proper lubrication before starting.


It should go without saying that when a pump is changed or drained for repair that clean hydraulic oil should then be flooded into the housing before the motor is started up again.  Unfortunately, the misunderstood concept of a hydraulic pump filling its own housing is all too common and sometimes this misinformation prevails, leading to much shorter component life than expected, higher repair and replacement costs and unexpected downtime, all of which are undesirable consequences of taking shortcuts or making assumptions about the speed at which a hydraulic pump will fill its own housing.

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