When rebuilding their early geeps, some railroads added air filter boxes (notably IC-Paducah), while others did not (Seaboard, despite extensively replacing other components). The difference led me to thinking about the reasoning behind the upgrade, and has led to two questions:
- What type of air filter system did the gp-7,9, and 18 have that led some RR’s to replace (upgrade) the to the type with the protruding boxes?
and:
- Since not all were rebuilt with new filter devices, and many original geeps are running today with their original system, how costly and/or difficult is it to maintain the original filter system these days? I guess the answer to that also factored into Seaboard’s decision not to replace them.
Thanks to all who respond.
Most early engines had oil soaked filters behind the grills/louvers - real messy to change out. Many railroad went to a ‘paper’ air filter system and the ‘ox yoke’ filters on those IC GP’s are a good example. Air was drawn through the filter box before going to the power plant. Changing out filters was easier. Starting with the GP30, EMD went to a pressurized carbody air system where all air was run through a centrifugal air cleaner(just behind the cab) before it was sent out through the carbody. GE had been doing this a couple of years before EMD.
What is left of 1st generation GP’s have some kind of paper air filter box(could be internal) for the most part. I am not familiar with SBD engine practice, but either they did not want to invest any more in an old GP, or they have some kind of internal filter box. Maybe some SBD fans have the scoop. I know BN/BNSF converted a lot of older GP’s with a filter box that just extends above the carbody. You have to have a good ‘down-on’ photo to see them.
Jim
Thanks Jim:
I am aware of the protusions and other changes made to the sheet metal on the long hood for many rebuilds. You’ve answered my question for the most part, but let me say it another way just for clarity.
Would most of the early geeps running today have had their oil bath filter replaced with a paper filter system despite not having any protrusions or visible changes to the long hood? Or does the unchanged long hood mean they likely still have oil bath filters?
If that is the case, do you think that the railroads that did alter the long hood when upgrading the filter system did so mainly to improve the access to the filter, since they apparently didn’t have to alter the long hood just to convert the filter system to paper?
Looking the gp15, which is a later generation of gp course, it has an access hatch but no odd protrusions where the air filter is. That same access hatch is generally not found on the earlier gps, nor have any seemingly been added over the years.
Sorry for being so technical.
Early Southern Paciifc conversions required a new housing that protruded above the roofline, as experience was gained during the conversions, the air filter package was redesigned to occupy the same space as the orginal, thus no outward signs of modfications.
The upgrading and relocation of the paper filter elements to within the carbody had a profound effect on Geeps built with the later single 48 roof fans which could not accomidate the eariler box design due to space constraints, thus the fan package also had to changed out for the earlier duel 36 fan package which provided sufficient room for the conversions. I believe only a couple geep nines were given a fan package swap before the mechanical forces perfected the new revisions with the express intent of avoiding this costly conversion.
SP gradually phased out the oil bath filter in the interest of a common inventory and a unified servicing procedure Paper filters also increased the mean time between replacement , also the carbody interior remained much cleaner without all that oil in suspension.
Dave
The GP15 series of engines is sort of unusual. EMD marketing set their sights on the old F unit/early GP market and worked out a trade-in scheme that could reuse parts from the original engine(reduced purchase price). One version of the GP15 had carbody filters, another version had the centrifugal air system - It depended on how much money you wanted to spend. Just because there were no protrusions does not mean that there is no new air cleaning system.
Jim
I understand. Thanks again guys.