1. Jacobs Engine Brake Retarder

ASME Landmark # 108 (1957)
Jacobs Manufacturing Company


This is the ASME Landmark that really got me interested in this little list of eight rather random engineering achievements in Connecticut. Two reasons: One, Jacobs Manufacturing is only a few minutes from my office and two, I’d read a bit about the company in the heartbreaking book, Smoke, Fire and Angels. Long, depressing story short: The dump truck that killed six people at the bottom of Avon Mountain (right near my house) was not equipped with a Jake Brake.

It looks like they used to be in West Hartford

“Okay,” you say, “I’m sure many trucks aren’t.” True, but get this: The Jacobs employee parking lot abuts the trucking company parking lot from which the deadly brakeless truck came. Adding sad irony to that is that one of the six killed that day was a Jacobs employee. That’s just craziness.

Now you may be asking why – well, the so-called Jake Brake could very well have saved those lives that horrific day. It works by slowing those big trucks down on downhills by retarding the whole piston/combustion process. In fact, large trucks can remain at a stable speed using the Jake Brake and not even touching their brakes. Yup, and this thing was perfected here – and is still manufactured here – in Bloomfield, CT.

jbbI wrote an email asking the anonymous emailbox if they knew about their ASME award and the next thing I knew, I was invited to go see it myself! I happened to have my camera so after work I stopped by and was treated to a mini-tour of Jacobs by a very pleasant man named Paul. Heck, he even held up the plaque for my picture – AND didn’t really make fun of me for wanting to see it (to my face anyway).

Paul explained how they will re-do their lobby and give the award a bit more prominence. He also said that they have the original Cummins Engine (or something) in storage equipped with the Jake Brake. You really should read the first few pages of the pdf below – the story of how this relatively simple thing works (turning the diesel engine into an retarder) is pretty cool, but the story of how Cummins (still an important name in engine stuff) came to invent the Jake Brake is fascinating. Seriously.

Notable for: first practical mechanism for braking large trucks with engine compression as they descend long, steep grades at controlled speeds

Owner site: Jacobs
Cummins Engine site: Cummins

More about . . .
The Jake Brake permits large trucks to descend long, steep grades at a controlled speed. It was the first practical mechanism for altering on demand the valve timing on a truck diesel engine, thereby converting the engine to a power absorbing machine. The modified engine can continue to power the truck in normal operation, allowing service brakes to remain cool for emergency situations. Invented by Clessie Lyle Cummins (1886-1968), this device (produced by the Jacobs manufacturing company since 1961) has contributed significantly to highway safety.

Visiting Info: regular hours: Mon-Fri 8-5:30 (But it’s not like a museum or anything.)

Really Great pdf: Seriously.


2 responses to “1. Jacobs Engine Brake Retarder”

  1. Raul Copelo says:

    I think this is a fantastic invention.
    I just bought a truck with a cummings 350 it’s just been rebuilt but J brakes electrical’s are not conected,would you be able to send me some information on this or diagrams on the electricals .
    Thank you R.C.

  2. Steve says:

    No. Please go back and read at least 2 sentences above to find out why.

Leave a Comment

The Out Campaign: Scarlet Letter of Atheism