Keim Steam Pump


The first pump manufactured was in 1993 of a 1” scale single cylinder pump based upon an article that first appeared in Modeltec. It took 2+ years to get it to operate somewhat reliably and after discussing the project with other club members who had tried to build the same model, I realized that I was not alone with my experiences.

During this time period (1990 – 1996), I was employed by the Ohio Central Railroad Steam Passenger department as a Fireman, Machinist, and eventually Steam Locomotive Engineer. The inspiration to develop a better looking and more reliable pump was reinforced each day when I would start up the pair of Westinghouse 9.5” single cylinder air compressors used for our train air brake system.

 1999, I started to design a scale pump using 3-D solid modeling software. The design criteria I set for myself was to:
1) make is scale in overall proportions (external cylinder diameter and length, overall height, bolt count, etc.)
2) Design to use O-rings wherever possible to avoid using graphite string packing.

For manufacturing, I incorporated into the manufacturing process for the Steam and Water piston bores to be honed on a Sunnen Precision Hone machine to ensure roundness, straightness, and smoothness of bore, thereby guaranteeing sealing ability of the O-rings while minimizing drag.

2000, I produced the first 1.5” scale water pump and offered it to a fellow Live Steamer for extensive testing.

2001, Two important developments took place. First, I incorporated the “stepped face steam piston” concept to all pumps. This allows more of the piston end face to be exposed to live steam when piston has reached the end of the stroke. With a flat face piston, the only surface area (and resulting force) acting upon the piston is the .078” diameter steam port opening at the ends of the cylinder. At 100 psi, the force acting upon the piston is only 0.477 pounds, hardly enough needed to overcome friction from all of the O-ring seals. This was recognized as a major reason why many other pump designs also tend to stall and fail in the field. I was asked to rebuild other pump manufacturer designs, fitting them with improved pistons which made them work just as well as mine.

                       Traditional Flat Face Piston                                                        Stepped Faced Piston

Traditional Steam Piston at end of cylinder stroke

Stepped Faced Piston at end of cylinder stroke showing steam space for easier starting

The second important development was to address the design, manufacturing, and operation problems associated with the composite shuttle piston + slide valve design commonly found on all single cylinder pumps.

Sitting in my living room during a wintry afternoon, I laid out the plans to make a single piston “switch” using only O-rings to seal the many ports to the cylinders, exhaust, steam supply, and signal ports. New fixtures and new tooling were designed and built and after the prototype was built, live steam testing proved that the response time for the pump to cycle was far superior to the previous design. In addition to the advantage of having a smooth straight bore for the shuttle piston to travel, there is also no large steam chest as with the previous design for steam to expand, cool, and condense into. The shuttle piston design solves the manufacturing, operation, and maintenance issues experienced with the traditional design. With only O-rings to replace, there is no more lapping and no metal-to-metal contact to scar the sealing surfaces.

2002 I designed and built the first 1.5” scale single cylinder air compressor easily capable of quickly charging up a scale reservoir up to within 5 psi of the steam cylinder pressure.

2002 Designed and built a 1” scale water pump.

2003 Designed and built the first 2.5” scale water pump

2004 Designed and built the first 2.5” scale air compressor

2005 Designed and built the first 2-cylinder, high flow rate water pump

2009 Designed and build Okadee style cylinder drains, using my shuttle piston design concept.

2009 Successfully tested Aflas elastomer O-rings for all steam sealing and switching applications.

2011 Redesigned some of the steam head drill fixtures, combining two drilling operations into one.

2013, Designed and built a practical Westinghouse cross compound top head assembly, using a piston style control valve.

Today, pumps are made on an “as-order” basis since each customer has unique pipe configuration needs. Many of the base components are in stock, leaving manufacture and assembly of the customer specific configuration components as the primary lead time driver.

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