MRO Magazine

Hydraulic systems ease the load but not the burden of safe operation


November 14, 2000
By PEM Magazine

Hydraulic systems generally store fluid under pressures from 2,000 pounds per square inch and more, and they use that pressure to help heavy equipment operate smoothly. But that kind of stress makes it easy for accidents to happen — if hydraulic systems aren’t properly maintained, safety can be compromised. The most common hazards associated with this equipment include burns, bruises, cuts, abrasions and hydraulic injection of fluid into the skin.

But plant professionals could face an even more dangerous hazard if hydraulic systems aren’t checked regularly. In some cases workers are seriously injured or even killed by runaway machines with faulty hydraulic devices.

Several years ago, a worker in an Ontario plastics manufacturing plant was killed when his head and shoulders were caught in the mould area of an injection moulding machine. According to the Ontario Ministry of Labour, the rear electric limit switch and hydraulic safety device were not engaged because someone had modified the hydraulic safety device. Similarly, a Saskatchewan worker was killed when a hydraulic outrigger jack cylinder failed, causing the digger truck unit it was supporting to fall on him. In this case, the unit had been stored outside in cold temperatures. The cold hydraulic oil expanded within the cylinder when it warmed up.

So, how do you properly maintain a hydraulic system to ensure the safety of everyone in the plant? There are a few things you can do to maximize safety. One is to make sure a one-way flow restrictor valve, or line throttle valve, is mounted on the inlet port at the base end of the hydraulic cylinder or cylinders. Also remember to allow for hydraulic oil expansion when equipment is exposed to increased temperatures. Make sure there is enough room in the cylinder for fluid to expand. Remember to check regularly for oil leaks and worn hoses. According to NIOSH, leaks in the hoses can lead to component failures. It advises running a piece of wood or cardboard along the hose to detect small leaks, rather than using fingers.


Alison Dunn is the editor of