Oil Field Masterpiece - Part II

The Restoration Comes to an End, and the Swan Runs for the First Time in Over 50 Years

| April/May 2004

  • Fresh bearing castings

  • Craig Prucha's 25 HP Swan
    Craig Prucha's 25 HP Swan out in the sun at the Coolspring Power Museum where it's on long-term display.
  • The Swan
    The Swan is really coming together by June 1999.
  • Craig Prucha runs the Swan
    A justifiably proud Craig Prucha runs the Swan during the Coolspring Power Museum's fall show in October 2000.
  • Fitting new head
    Fitting the new head in February 1999. Note the fixing bolts, two of six 38-inch-long tie rods that bolt the cylinder assembly together and to the bedplate.
  • Machining the cylinder-locating plate.
    Machining the cylinder-locating plate.
  • Cylinder sleeve, cylinder jacket and piston assembled to bed plate.'

  • Piston-connecting rod.
    Machining the shoulder on the new piston-connecting rod.
  • Trial fitting cylinder sleeve (with piston).
    Trial fitting cylinder sleeve (with piston).
  • Mixer and governor before disassembly.
    Mixer and governor before disassembly.
  • Restored mixer and governor
    The restored mixer and governor highlight the work that went into this engine's restoration. Note the new governor gears.
  • Big-end bearings and strap


  • Fresh bearing castings
  • Craig Prucha's 25 HP Swan
  • The Swan
  • Craig Prucha runs the Swan
  • Fitting new head
  • Machining the cylinder-locating plate.
  • Cylinder sleeve, cylinder jacket and piston assembled to bed plate.'
  • Piston-connecting rod.
  • Trial fitting cylinder sleeve (with piston).
  • Mixer and governor before disassembly.
  • Restored mixer and governor
  • Big-end bearings and strap

Editor's note: This article is the second installment of a two-part series chronicling Craig Prucha's restoration of a 25 HP 1901 Swan oil field engine. Part I appeared in the March 2004 issue of GEM.

With the engine bed and cylinder prepped, I turned my attention to the sideshaft assembly. The sideshaft was pretty well rotted away, so I made a new one from stainless steel and bought a new set of gears for driving the governor. The new gears are nice, and they came with a small hole bored in the center so I could machine the gear's bore for my particular application. I was very fortunate to find gears that exactly matched the center distance of the sideshaft and the governor shaft. There are, however, some differences between the original gear set and the new gear set. For one, the number of teeth per gear is different (although the ratio is the same), and the tooth profile of the new gear set is different.

The governor assembly was the next part of the restoration to tackle. The governor shaft was rusted solid in the governor housing, and the governor housing had a crack in it from rust and moisture swelling and expanding. The governor parts are pretty fragile, so to make sure nothing broke during disassembly I drilled out all the pins holding the governor balls. I cut off both ends of the center shaft and heated up the housing with a torch. I did this repeatedly - followed by a good soaking in kerosene - but I still couldn't get the parts to free up. Finally, I put the governor housing in a press, and the shaft started to move. The shaft finally came out, and I repaired the cast iron governor housing by welding the crack with Ni-rod and grinding it flush.

Heads Up

With a materials list in hand, I made another trip over to my friend Dave Johnson's shop and got the necessary stock to fabricate a new head and cylinder sleeve mounting plate. The engine was also missing the brass bearing halves for the connecting rod big end and the strap that holds the big end and bearings together on the crankshaft. Using a bearing half of similar size from another engine, I fabricated a pattern for two bronze castings, one for each bearing. I fabricated the strap for the connecting rod, and after getting the bearings back from the foundry, I machined them up.



I first squared up the bearing halves on a shaper and clamped them in a four-jaw chuck on my lathe. I put a piece of 0.060-inch nylon shim stock between the two bearing halves and machined the bore to size. I faced each side of the bearing assembly, and machined a chamfer into the inside diameter of the face to make clearance for the radius of the crankshaft. Finally, I drilled an oil hole and cut oil grooves in the bearing surface. I assembled the bearing halves together with the strap and the connecting rod.

Next, I turned to pouring the crosshead babbitt. Before I could pour the babbitt, however, I had to finish the  cylinder sleeve mounting plate and mount the cylinder sleeve. And that meant I had to finished fabricating the new piston connecting rod - all or which play a critical role in aligning the crosshead.



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