Dry Running Pumps: What is it and Why is it Harmful?

Blog | August 18th, 2019

Hydraulic oils transmit and amplify actuator-controlled forces. They deliver those kinetic energies to mobile vehicle pistons and crane booms. In addition to that principal function, the fluid also cools and lubricates the fast-moving machine assemblies inside a hydraulic system. Hydraulic pumps, because they’re participants in this balanced fluid conveyance process, should never run dry. Regrettably, that’s exactly what happens when a system pump isn’t primed properly.

Hydraulic Pumps Need Lubrication

Fluid-based equipment parts are endowed with abilities that mechanical systems lack. Think about a simple mechanical system. If it has a pump, it’ll need a pair of oil-lubricated bearings, plus a casing that’s designed to dissipate frictional heat. Well, hydraulic machinery can carry out the same actions, but they do so with fewer resources. It’s the oil, the fluid energy transmitter that collectively performs all of these features. The fluid cools, lubricates, and provides that all-important energy transmission attribute. Therefore, without the oil, running dry, a hydraulic pump won’t function. More accurately, it’ll operate, but its parts will grind together, generate heat and create a wear-and-tear incident that’s impossible to recover from.

Maintaining the Fluid Levels

So the solution is to never use a dry-running pump. Surely that’s an easy enough rule to respect. Not so fast, there are a few caveats to that rule. For one thing, the fluid won’t always be there when a pump is actuated. It perhaps starts prematurely, without the backing of a fully-loaded system reservoir. Working without being primed, there’s a film of oil covering the exposed parts, so the equipment doesn’t seize up straight away. But the gear is going to age prematurely. Its parts will rub together and create friction. To avoid the oncoming failure, equipment operators should never dry start their gear. The pumps must be primed and sealed before they’re started. Generally speaking, this rule applies to older hydraulic equipment. With modern gear, their pumps won’t operate if they’re not primed. All the same, a mobile hydraulics trainee should be well-versed in the basics, for automated equipment features are far from perfect.

At least three important functions become available when a mobile machine’s hydraulic oil levels are maintained. Sure, the energy transmission feature is vital, but then there’s the fact that the wet stuff also carries away excess frictional heat. More importantly, the oil is a lubricant, so it prevents the rubbing action that produces this side-effect. Dry running pumps, including those that haven’t been primed properly, will experience wear and excessive amounts of thermal energy. Suffering like this, a premature pump fail becomes entirely likely. Lacking priming or empty because of a recent maintenance task, oil levels must be checked periodically.

Mobile Hydraulic Specialties Pty Ltd

Factory 89, 38-40 Popes Road
Keysborough, Victoria, 3173

Phone: (03) 9798-6511

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