The TS3 'Commer Knocker' engine
Tech & Auto
What Makes The Commer Knocker One Of The Strangest Engines Ever Built
While most engines made in the last 100 years have adhered to the standard single-piston per-cylinder design, the TS3, also known as the "Commer Knocker," is an exception.
This supercharged three-cylinder, two-stroke diesel engine used by the British commercial truck manufacturer Commer in the 1950s and '60s featured an opposed-piston design.
The opposed-piston engine has been utilized since the 1920s and uses two pistons in each cylinder mounted with the heads of the pistons facing each other.
The TS3 engine differs from others as it has one crankshaft instead of two. Additionally, one piston is designated as the exhaust piston, and the other serves as the air intake.
The exhaust piston had a much shorter travel distance to ensure its port was sealed when air was pulled into the cylinder.
This quirk and the large lobe-shaped blower that captured exhaust gases and forced them back through the intake manifold set the TS3 apart from other opposed-piston engines.