Woodward Herringbone Gear Pump (XX Pump)

Woodward produced various sizes of XX Pumps. While the reference numbers are the same, the parts required for XX Pump maintenance are specific for each pump size and motor frame. Please for assistance in determining which part numbers are appropriate for your unit.

See our Factory Repair Bulletin below for more information.

Advanced repair services include:

Basic pump overhaul includes:

XX Herringbone Gear Pumps are very robust and will last many more years with routine maintenance. In addition to basic pump overhaul services, we offer advanced repair services and have been able to repair some severely damaged pumps that customers thought were beyond saving.

Factory repairs save you money compared to a service call and allow us to perform additional services that are difficult or impossible to do in the field.

Our Training and Repair Facility offers for XX Herringbone Gear Pumps.

Factory Repair Service

Because of the special nature of these pumps, new, drop-in replacements are not available. Engineered replacements can cost in excess of $75,000 which makes routine maintenance a bargain.

Customers have resisted the 5 to 7 year recommended time frame because the pumps have been running for 15 plus years without problems. These pumps are running on borrowed time.

Severe damage can occur if regular maintenance is not performed. Woodward recommends that the bearings be changed every 5 to 7 years.

The Herringbone Gear Pump is better than a standard spur gear pump because each set of teeth begins its fluid discharge phase before the previous set of teeth has completed its discharge phase. This overlap (and the relatively larger space at the center of the gears) tend to minimize pulsations and give a steadier flow than the spur gear pump.

The clearances between the gear teeth as they mesh and between the teeth and the pump housing are very small. The inlet port is connected to the suction line from the sump, and the outlet port is connected to the pressure line which feeds the accumulator and governor distributing valve.