Large Diesel Engines – Using the Mainline as the Reference Point

At left, CAT 3616 block in Rottler F109. At right, CAT C175-20 in Rottler F105A

Large High Horsepower engine blocks have their own inherent and unique wear factors.   Machining the deck and cylinder bores while using the mainline as the reference point is critical to proper alignments and efficient operation – consider this…

C175-20 block in Rottler F105A using the mailline as a reference

The exact same engine block could be used in many different and demanding applications such as mining, marine, stationary power, oil and gas.   Take a mine truck for example… the engine is under tremendous load and stress with variable and extreme cycles.   The block undergoes torsional fatigue, liner seating issues, fretting on the deck, etc. etc.    As machinists, we always need to consider the best repair strategy that will yield better overall reliability and uptime for the operator.

Unlike most traditional bore mills which use the pan rail as reference, Rottler’s EM100s series machines use the main line as the reference point for machining.   There are a number of key benefits which include:

  • The decks are machined parallel to the main line to within .001”.  This allows for consistent piston protrusions for engine assemblers.   Torsional fatigue / gasket sealing finishes are properly addressed yielding better engine life with fewer problems.
  • The upper and lower receiving bores are machined perpendicular to the deck while achieving better concentricity.   This equates to less fatigue on the liner flange due to better alignment.
F105 line boring CAT 3508 block with CAT 3408 setup for deck / bore work

This simple difference is one of many examples of how Rottler Manufacturing teams up with machine shops and engine builders in critical industries to improve overall engine performance and reliability.

Stay tuned for the next technical bulletin in this series… or go to for more information.

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