Gear-type Flow Dividers

By Gary Alexander, CFPHS

Many components are available that provide similar – or even identical – function in a pneumatic system as in a hydraulic system. Cylinders and valves, for example, operate very similarly, and there are few differences between the pneumatic and hydraulic versions of these components.

Flow dividers, however, are hydraulic-specific components. In order to perform their designed function correctly, flow dividers require the non-compressibility found only in a hydraulic fluid. They would not operate properly with compressible air as the medium.

As the name implies, flow dividers are used to divide pump flow into smaller flow increments with a high degree of accuracy, regardless of the actuator loads these smaller flows eventually move. The flow divider might divide the pump flow into two, three, or four equal flows, or it might divide the main flow into unequal smaller flows for a particular application to allow a proportional flow to differently sized actuators. This flow division can be very useful in synchronizing hydraulic cylinders or motors in both mobile and industrial applications.

Flow dividers are made with different internal components, which affect how the flow divider performs. Gear-type flow dividers are basically a combination of two gear pumps connected to be able to work in unison. A gear-type flow divider will not only divide the flow in one direction, but it will also “combine” the flow in the opposite or reverse direction. Depending on the rest of the circuit, a flow divider-combiner can be extremely useful and may simplify the circuit by eliminating other components.

Flow dividers also have many other uses beyond simply dividing (and combining) flow. They can be used as pressure intensifiers or flow multipliers in a hydraulic circuit, which would then reduce the required pump size. By reducing pump size, the flow dividers will then help keep horsepower to a minimum and thereby reduce the initial cost of the system. Making these main components smaller will help reduce the ongoing operational costs of the hydraulic system and will also provide less expensive replacement parts when needed. A flow divider can also be used to provide the flow to a kidney-loop filtration circuit. In this case, an extra pump and motor combination would not be required to provide low pressure and flow to the recirculation filter loop.

Because flow dividers are hydraulic-specific components, they are not generally as well understood as components that work with both hydraulics and pneumatics. Additionally, the gear-type flow dividers may have significant “leakage” flow, which must be taken into account in any flow divider application. The Certified Fluid Power Specialists at Quality Hydraulics & Pneumatics, Inc., will be happy to assist you with your flow divider specification and application, ensuring that you incorporate the right cost-effective component for the job.