Cartoon stick figure standing next to an HVAC compressor having a terminal with a cloverleaf (Y) shape — representing a blog post about the Fusite Cloverleaf shape mark trademark registration.

Trademark: Fusite Cloverleaf Terminal Shape

First Used: 1960

Registered: 1946

Current Owner: THERM-O-DISC, INCORPORATED (SENSIENCE) [1]

Trademark Type: non-traditional trademark; trade dress; shape mark

Primarily Associated With: hermetic terminals [2]

Brief (and likely incomplete) History [3]:

The Fusite Cloverleaf Terminal shape mark is an important piece of trademark history. It is one of the oldest, still-active shape mark registrations in the US! What’s the story on Fusite and what even is a hermetic terminal anyway? Read on to find out more!

Founded in 1942, Fusite specialized in hermetic sealing for HVAC/R compressor terminals, including one-piece, sealed glass-to-metal electrical feedthroughs. Its name came from that technology: glass fused to metal to create a tight seal around electrical conductors. In simpler terms, a glass-to-metal hermetic feedthrough allows electricity to pass into a sealed container without letting air, moisture, refrigerant, or other gases leak in or out.

That made FUSITE® [4] electrical feedthroughs especially important in the refrigeration industry, where the terminals were used in sealed compressor systems. In refrigeration and air conditioning systems, the compressor has to remain sealed while still receiving power from the outside. Fusite’s pitch focused heavily on reliability. The terminal did not just carry electricity into the system; it helped manufacturers build sealed compressors that were consistent, durable, and resistant to leaks.

One of Fusite’s most recognizable designs is its hermetic terminal having a front surface shaped like a cloverleaf or “Y”. The Fusite Cloverleaf shape mark has been used since 1946, and by the late 1950s the company was heavily advertising it directly to the refrigeration industry. One ad described the “distinctive Cloverleaf or Y configuration” as the “shape of trouble-free production,” while another noted that the terminal itself had the cloverleaf configuration typical of Fusite refrigeration terminals. Fusite also backed up that reliability pitch with numbers: one ad claimed that a major user built more than 2 million compressors with Fusite terminals in 1956, with only 69 glass leaks.