What do Lovejoy jaw coupling numerical sizes stand for?

Most products in the industrial sector have straight forward naming conventions that can be easily understood by looking at the specification sheets of the related components. Be it max torque, length, outside diameter... there is usually some rhyme or reason to the sizes of a given product.

But what about the Lovejoy jaw coupling? What exactly does the "35" mean in an L035, and how is that relative to the "150" in an L150 jaw coupling?  Looking through a catalog, the answer is far from obvious. No single feature of the coupling matches these numbers.

The secret lies in history. At one point in time, remember Lovejoy first launched the jaw coupling in 1927, the number signified the max bore of the jaw coupling. A L035 had a max bore of 0.35 inches, and a L150 had a max bore of 1.5 inches.  Over time, given technical advances of steel and rubber technology (Lovejoy's elastomeric spiders were original not rubber but layered leather), the max bore of these coupling hubs increase while the components themselves maintained the same external dimensions.

Given the product dimensions remained the same (other than they could now be bored out larger), Lovejoy opted to maintain the legacy naming structure... and not rename it every time technology allowed the performance specs of the product to be increased.

Today a L035 has a max bore of 0.375 inches and the L150 has a max bore of 1.875 inches.

Bonus Fun Fact: Lovejoy's proprietary standard NBR rubber spiders have and continue to include SOX in the product description. While many (internally and externally) assume that SOX is an acronym or reference to a feature of the product, the reality is much more lighthearted. Around the time of the spider's development, the owners of Lovejoy (located in Chicago) were close to members of the Chicago White Sox (and also avid fans). As such, "SOX" was embedded into the product description as a hidden shout out to Lovejoy's favorite baseball team. Today's Lovejoy is heavily splintered, both in regards to favorite baseball teams as well just about every other professional sport, so perhaps this information should be suppressed? Nahhhh.... this blog is like TMZ. The cat is out of the bag!