Diesel Locomotive Pocket Guide 3/1978

Karl - Good observations on the E7's! Though the Frisco and the Katy originally regarded the two-unit E7 sets as a single locomotive, at least the Frisco had the sense to number each differently. The two MKT E7's were MKT 101 & 101A, and/or 101A & 101B or 101A & 101C, or something like that.

Also note no mention of top speed on the original E7's. They would fly like the wind - far faster than anyone had the right to go on the curvy hog-back profile down the Frisco Eastern Division from StL.

FYI, I posted the question to the Katy HS and to a couple of MKT friends about the gearing on the MKT E7's. We'll see what they say.

And .... I forgot to crop the rebuilt E7 diagram. It's reposted below. I'll get this right yet!

Ken

ps - Note also the E7's had only one steam generator, 3000 lbs, while the E8's had two 2500 lb units. You always wanted to be riding behind a set of E8's in January/February!

 

The gear ratio 57:20 means that for every 57 revolutions of the electric traction motor, the axle (wheels) will revolve 20 times. Or... a ratio of 2.85 to 1.

Most of the time gear ratios are expressed in the latter format; resolved to a number versus 1. Typically the number is derived from the number of drive teeth in a gear set compared to the number of driven teeth in that set.
Example: if the drive gear has 80 teeth and the driven gear has 228 teeth, then the gear ratio is expressed as 228/80 or 2.85:1. This may be pretty close to the actual number of teeth on the gears in drive unit!??

My response is based on a generic technical background.

I'm sure I will be corrected by someone technically oriented in railroading if I am wrong.

 

Sherrel -

See, that's the problem with you jet pilots - you never had to shift gears!

55:22 on the original E7's means 55 revolutions of the traction motor spins the truck wheel 22 times. This is a higher (faster) gearing than the 57:20 ratio, where it takes 57 revolutions of the traction motor to spin the wheel only 20 times. Obviously, the 57:20 is a "lower" gear, better for tractive effort, better for starting up, better on hills, but ..... slower at the high end.

There is a gear on the end shaft of the traction motor, and a gear it meshes with on the truck axle. There are multiple ratios available for them.

Ken

 

Well, it really depends on the ratio between the two, as Keith explained.

For example, the Frisco EMD F3's had a gear ratio of 62:15, a ratio of 4.133. The Frisco ALCo FA's had a ratio of 74:18, for a ratio of 4.111. Essentially the same, so Frisco's EMD F3's and ALCo FA's easily ran together.

Note these ratios arer quite a bit "lower" (higher number) than those for the passenger E's. These were freight locomotives, built to pull, not run. The max speed for the F3's and the FA's was listed on the diagram as 65MPH, quite a bit lower than the E's.

Ken

 

Update - I have not heard back from the Katy RR HS yet, but it turns out I do have a diesel diagram book for Katy's diesels. Shows you how well I remember what stuff I have back in the "stacks".

Interestingly, it is also a "vest pocket" diagram book, very similar to the Frisco ones.

Looking at the 4/7/55 MKT issue, the answer is "yes", the Katy did regear their two Texas Special E7's, MKT 101A & 101C, down to 57:20, just as the Frisco did to the SLSF E7's. The diagram does not show the previous ratio, but it obviously has been updated on the sheet, and these units were almost certainly identical to the Frisco E7's when purchased, with an original gear ratio from EMD of 55:22.

The Katy's E8's that they bought after the two E7's were also geared for 57:20, just as the Frisco's were.

The verdict must have been 100% - neither railroad liked those 55:22 speed demon E7's.

Ken

 

Karl - Indeed, you are correct. I overlooked the Rev AA.

Here are the vest pocket issues I have. Does anybody have any others?

8/15/52 (no Rev letter, signed by Lee Buffington - makes it a treasure!)

Rev F (no date)

Rev H (no date)

Rev K (no date)

Rev W 9/73

Rev Y 3/78

Rev Z 11/78

Rev AA 2/80

Ken

 

Whoa!, I stand corrected! I thought I had more Frisco vest pocket diagram books than those I listed above, but I couldn't find them all. Reason is, the others are xerox copies of issues Lee had. He let me borrow them and copy them. I have not gone to the trouble to cut all the copies up and make them in the vest pocket sized booklet. So, here's the complete list I have, including the copies:

8/15/52 (no Rev letter, signed by Lee Buffington - makes it a treasure!)

Rev F (no date)

Rev H (no date)

Rev K (no date)

Rev M (no date)

Rev R 5/68

Rev T 1/70

Rev U 6/71

Rev V 6/72

Rev W 9/73

Rev Y 3/78

Rev Z 11/78

Rev AA 2/80

Now I feel better. I recall Lee saying he had a bunch of others, but he couldn't find them. I bet he had them all during his time with the Frisco!

Again, does anybody in the group have any other vest pocket issues?

Ken

 

Mike, Chris -

I suggest you put a copy of Keith's posting above of the Frisco Vest pocket Diagram booklet, Rev Y, of 3/78 (the start of this thread) in the Diesel Diagrams folder. That way it will be easier to find in the future.

Ken

 

The copy has been posted in Diesel Diagrams.