Gear-type flow dividers work well, but if any one of the gear section outlet piping leaks, aerates, or builds pressure before the other sections, pressure intensification can occur. This does not happen on spool type dividers.

Take a 2-section gear type divider driving two cylinders. If one cylinder bottoms out, pressure will build in that cylinder. However, if the other outlet port has no pressure on it, this gear set acts like a hydraulic motor that has a drive shaft driving the other pressurized gear set. This torque along with the incoming pressure could intensify the pressurized cylinder to twice the system pressure. A 4-section divider could intensify a pressured line four times the incoming pressure.

This type of application requires a safety relief in each flow divider outlet to allow the pressure to maximize at a safe level and allow the flow divider to continue to turn and fully extend all the cylinders. The relief valves can act like a reset devise each time the cycle is completed.

Installing flow dividers requires care and a good understanding of how to bleed air from and synchronize the system to prevent pressure intensification.

In this case, the press maintenance group did not realize the importance of fixing any leaks in the cylinder lines and the correct installation procedure. However, the designer of the system should have used flow dividers with individual reliefs in the outlet lines of each section to prevent this problem.