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Hydraulics 2013


This note is a description of the project to restore the hydraulic systems on USS Pampanito. It is also thank you note to the individuals and corporations that made it possible.

A general description of the system can be found in The Fleet Type Submarine Online Submarine Hydraulic Systems.

During the summer of 1945, after her sixth war patrol, Pampanito had major upgrades to her hydraulic systems. As far as we know, the hydraulics were not used during the 1960s when Pampanito was a reserve trainer. During the 1990s, volunteers restored the original system. They operated the periscopes, bow planes (rigging and turning), main induction, and in drydock, all the torpedo tube shutter doors, stern planes, and rudder. The ballast tank vents are not enabled. The system was periodically operated, particularly during the 1999 and 2007 drydockings.

The original hydraulic system uses high pressure air in an accumulator. Although the accumulator can be bypassed, this causes stress on the system components. Over time it has become more difficult to safely provide high pressure air for the system (high pressure air compressor, hydrostatic testing of air flasks, tests of safety valves, etc.) As a result, the hydraulic system fell out of use shortly after the 2007 drydocking.


During 2013, volunteer Charlie Butcher, Master Chief (Ret), lead a project to acquire and install an auxiliary hydraulic pump that does not need high pressure air. The goal was to be able to operate the hydraulics without high pressure air, and without any permanent changes to the boat. So the entire system had to be installed in a way that it could be removed without any sign that it had been in place (no new holes drilled.) The team that included Manson Construction, Hydraulic Controls Inc, Bosch-Rexroth and Pampanito volunteers, not only met this challenge, but they also installed it in such a way that the original plant can still be operated with the modern pump installed.

Key to the project was the donation of a modern Bosch-Rexroth rotary swash plate pump that did not require an accumulator. To access the original hydraulics without damaging anything, a clean out cover was removed from the original hydraulic volume tank, and a replica including new hydraulic ports was fitted in its place. In a similar way, a replica filter housing was created with a hydraulic port. The original clean out cover plate and filter housing are stored in the museum collection. The replicas can be unbolted and the originals re-installed at any time.

Another benefit was the addition of modern, small particle filters to protect the system.

Clever brackets were fabricated by Manson Construction to take advantage of existing bolts and holes to support the pump, motor controller, modern high quality oil filters, safety gear, etc.

Unfortunately, no path for the 480 VAC power was found between our modern, GFI protected supplies in the after battery and the pump room. So a portable cable is run when the auxiliary system is operated. We used high safety Hubbell pin and lock connectors.

After a bit of cleaning, and greasing, on 19 Sep 2013, #1 and #2 periscopes (each 2,000 lbs.) where raised hydraulically.


Before the next drydocking, the crew will test and document with checklists the operation of much of the hydraulic systems. The goal is to be ready to quickly operate the bow planes, torpedo tubes, rudder, and stern planes in drydock to allow access behind the equipment for maintenance.

photo of periscope up


We appreciate the advice, help, and donations from individuals and companies that made this project possible:


Volunteers and Staff of USS Pampanito,
Charlie Butcher, Jim Kyser, Kevin Peterson, Rufus Lazarus


Manson Construction Co.,
Hydraulic Controls Inc.,
Bosch Rexroth,
Hydraulic Hose Service Inc., 1451 34th St., Emeryville, CA 94608


Beck Electric Supply,


sketch of system
Sketch of the system

photo of in front of pampanito
Pump arrives.

photo of pump in pump room
Auxiliary pump installed in the pump room. Note the original IMO hydraulic pumps behind it.

Photo of filter housing with replica
Original on left, replica with fittings on right

Photo of filter housing
Replica filter housing with added connections for the modern system.

Photo of scopes up from pier
Periscopes raised. A lot of the work is done before visitors arrive.

Photo of scopes up from pier
Periscopes raised on hydraulics.


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