|Reversing a F-M 38D 8 1/8
Post Number: 1
|Posted on Friday, October 28, 2005 - 02:13 pm: ||
I saw your post and have a couple of questions and cant seem to find an answer for about Fairbanks Morse 38D 8 1/8 OP's .I have been around a lot of marine / generating station equipment and involved with a lot of OP's on tugs with reversing gear boxes but a lot of referance has been made to direct reversing units. All of my experience has shown me that the F-M OP's direct drive all the accessories-- fuel, oil and water pumps and the blower off of the crankshafts, not to even mention crankshaft timing 72 and 28 degree timing stuff etc. Enterprise and Superior engines are pretty sraight forward with a slip of the cam with WABCO controls but not the F-M's. Any help would really be appreciated.Check out my freind Franz Von Reidel's web site at www.northeasternmaritime.org. Its strange the stuff we talk about around a cup of coffee but I promised him I would find an answer. Thank you in advance, you must help a lot of knuckleheads!!!! Best regards, Bill Stephan 630 920 8816 email@example.com
I should be demoted to MM 3rd for this one LOL.
Post Number: 5
|Posted on Monday, November 14, 2005 - 09:09 pm: ||
Bill, the lag and lead was achieved by the position of the respective ports in the liner, not in the gear train. Some F-M's used gear trains and others had a shaft drive with bevel gears. There were two camshafts, one either side with both ahead and astern cams,a fuel injection pump either side and two injectors per cylinder. Can you follow that? I have a section drawing somewhere, will look it up tonight.
|Posted on Saturday, May 27, 2006 - 08:29 pm: ||
Here's your answer, even if it is too late for you to find it.
The upper and lower cranks are connected via a vertical shaft operated in/out with spiral bevel gears. A very few had variable crank timing- not many.
Not all Fairbanks had two injectors per hole. Regardless, all injectors on the direct reversing engines work for both directions.
The injector timing is changed for reversing by an arrangement which changes the camshafts' position relative to the crankshafts. The camshafts are driven by a multi-row chain and by shifting a device that has some idler gears on it, the cams move, relative to the cranks.
While this device is fairly simple, some find it difficult to comprehend, even when staring directly at the factory's cut-away display that is a hand's on demonstrator. They watch it do it's thing and still don't get it.
I don't mean to sound chauvanistic, but this is a fact.
Anyway the cams rotate into correct position and fire all injectors for each direction.
Concerning the various pumps here's how that is done: The fuel transfer pump, the scavenging blower, the lube oil pump, and the lube oil scavenging pump all have their own "reversing valves". They are really pretty simple. Both sides of each pump connects to a valve "box" that has a series of check valves that "convert the pump's porting to suction or discharge, depending on rotation.
These reversing valves are automatic. Since these pumps are all positive dispalcement types, the rotation of the pump causes flow which pushes the check valves into the needed positions. When the engine is started up in the opposite rotation, these reversing valves all move into position according to the out flow of the pump.
The raw water pump and the cooling water pumps are pretty ordinary centrifugal pumps. They will pump water in either direction but much better in one direction which is used for foreward (ahead). In reverse, the pumps still work but with reduced performance, but this is acceptable since reverse will be used relatively little.
I hope this makes sense. I ran a direct reversing O.P. for thousands of hours.
|Posted on Tuesday, April 08, 2008 - 03:23 am: ||
Does anyone know about Fairbanks Morse 4 cylinder 38D 8-1/8 with Universal Gear Corporation Reverse Gears? We have a old buoy tender "the Fir" we are trying to get going and am having trouble figuring out the gears (how they work, oil kind and capacity, oil filters etc etc) we dont have any manuals or instructions