Hydraulics 101

It's time to make sure your technicians know their hydraulics

The model had no safety devices to hold the bed in a raised position, so an external safety jack stand was needed between the bed and frame of the truck when the bed was raised, but the technician--working alone--did not put the jack up. When he climbed between the bed and frame and disconnected the hose attached to the hydraulic ram that held up the container, it released the pressure in the system, causing the truck bed to fall on him.

Barnes, who devotes the first four hours of his week-long hydraulics classes on safety, says being crushed by a falling bed is just one of many potential dangers.

"I've seen guys have a small leak and they'll stick their hand behind the hose and tell someone to shift the valve to see where the pressure's coming from, and the oil coming out of there could penetrate your skin and shoot a hole through your hand," he says.


The hydraulics on medium-duty trucks might be one of the most dangerous, yet most-misunderstood systems on the vehicles. It is one area where some technicians seem to make repeated mistakes, misdiagnosing problems and unecessarily changing out parts, driving up both labor and parts costs.

The core problem is that many technicians do not receive proper training on hydraulics to begin with, and in other cases, years of working on the systems without incident can create a false sense of security, and when accidents happen, they can be sudden and fatal.

Make sure your technicians understand both the complexities and dangers of hydraulics systems, and your fleet will realize the benefits of fewer parts replaced and fewer hours lost to injuries, or worse.

Hydraulic System Safety Tips:

• Ensure lift beds of trucks are properly supported before performing maintenance or repairs.
• Ensure mechanics release pressure in hydraulic systems that are supporting loads or otherwise under pressure before beginning maintenance or repairs.
• Develop and implement a job hazard check sheet that all mechanics fill out and supervisors check and verify prior to staring each work assignment.
• Develop and implement a PM program which includes pre-shift inspections of the vehicle's operational systems and safety devices and the correction of identified defects prior to placing vehicle in service.
• Know the dump bed system owner's manual, including proper inspection and maintenance of the system and the safe work practices concerning system inspection and maintenance.
(Source - National Institute for Occupational Safety and Health)

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