Rusty Hopper's Modeler's Corner

O-ring Ramblings

| February/March 2004

  • Scale Gardner
    Two views of Robert Brandie's scale Gardner No. 0. The Gardner No. 0 was first introduced in 1895 and rated at just over 1/2 HP, but output was eventually increased to 3/4 HP.
  • Scale Gardner
    Two views of Robert Brandie's scale Gardner No. 0. The Gardner No. 0 was first introduced in 1895 and rated at just over 1/2 HP, but output was eventually increased to 3/4 HP.
  • Corliss steam engine
    Maury Uebelhor's scale Corliss steam engine. This prototype was made from bronze, but Maury plans to build another from cast iron.

  • Scale Gardner
  • Scale Gardner
  • Corliss steam engine

Hello again everyone. The other day a friend of mine asked me about using an o-ring instead of piston rings in a scale engine. I love the idea, and I use o-rings in most of the models I build.

Further, sometimes I install a cast ring in the ring groove below the o-ring. After the engine is broken in I'll pull the o-ring and install another cast ring, which gives it great compression.

The o-ring method will give you some piston slap as you are running only one 'ring,' and it is at the top of the piston. In my experience this hasn't caused any problems.

If you want to run an o-ring, here is the way I do it. First, fit the piston close to your bore size -just so it passes smoothly through the bore. Next, cut the groove you normally would for a regular cast ring. I have found that each o-ring needs a custom fit as they come in many different sizes, both in diameter and thickness. With the o-ring installed, you want the piston to fit snug in the bore since the o-ring will expand some.



Now, I know some of you are thinking an o-ring won't last for long, and you're right. The engines I have built (and those of some friends') with o-rings will generally run for about 100 hours before the o-ring fails. If you think about it, that's some serious running time over the course of a season.

One benefit of using an o-ring is you don't need a great hone job to seat the rings, as a smooth bore works best with an o-ring. Have you ever looked at the inside of a hydraulic ram? They have almost a polished surface.



SUBSCRIBE TO GAS ENGINE MAGAZINE TODAY!

Gas Engine Magazine A_M 16Gas Engine Magazine is your best source for tractor and stationary gas engine information.  Subscribe and connect with more than 23,000 other gas engine collectors and build your knowledge, share your passion and search for parts, in the publication written by and for gas engine enthusiasts! Gas Engine Magazine brings you: restoration stories, company histories, and technical advice. Plus our Flywheel Forum column helps answer your engine inquiries!

Be sure to take advantage of the Square Deal Subscription Program.

  • No Missed Issues.

  • No Renewal Notices.

  • No Additional Cost.

The Square Deal Subscription Program is designed as a paperless transaction with automatic renewals at a preferred low rate.   With advanced electronic notification, a 100% satisfaction guarantee and an easy opt-out plan, the Square Deal Subscription Program is the best value, risk free, eco-friendliest way to subscribe.




Facebook YouTube

Classifieds