- Joined
- Jan 1, 2014
- Messages
- 233
Here is my effort at making a 2 cylinder air driven engine. Design is common for a stationary engine with sliding valve air chest, eccentric cams, 90 degree crank, and reversing mechanism. Didn’t have any blueprints so pretty much made things up as I went along. I used a 1” bore, 1-1/2” stroke, 3/8” eccentrics and 6” flywheels having 1” wide rims and 2” hubs. Used solid Delrin pistons sans rings in C12L14 steel sleeves. Rods are 4” centre to centre while the eccentrics are 5-1/4”long. Made extra long cylinder & air chest flanges with integral 1-1/2” long bronze bushing in lieu of crossheads for the piston rods and the same for the valve rods. Seals of HDPE in lieu of stuffing glands on all of the rods. Piston and valve rods are 1/4” CRS. Everything was bolted down on a HDPE base with a stay rod between the cylinders and the centre crank web to give rigidity between the two engine sections. The expansion and lifting links gave the biggest difficulty. Made three versions of the expansion link and eccentric rods but didn’t like the way they “danced” on the ends of those rods due to location of the pivot points. Also tried a centre pivot expansion link with single eccentric rod but liked the look and action of dual rods. Finally decided on a sort of boxed link but with coincident pivot points to reduce movement. I also found that the lifting link moved the least when attached at the centre of the expansion link. Engine runs and reverses fine on about 10 lbs of air. Haven’t checked the RPM but this type of engine was never meant to run fast. It has a really interesting exhaust note. At really slow speed the engine “lopes”. Overall the engine is 6” high, 12” wide, 14” long and weighs 18 lbs.
Hope you find this interesting.
Hope you find this interesting.
Attachments
Last edited: