I need help identifying a gear on a Logan 920

[Rock]

I see what you mean... 820 here, but similar setup... and in mine, the gear works with the rest of the setup...

View attachment 482151

Yes, your setup on your 820 look's identical,.........I am curious, how many teeth are on the stud gear of your 820?

 

[wachuko]

Yes, your setup on your 820 look's identical,.........I am curious, how many teeth are on the stud gear of your 820?

Looks to be 24 …. But I am not in Orlando at the moment to measure diameter.

Best to just call Scott Logan and get his help on this. With model and serial number, he should be able to tell you which one it is.

If I looked it up correctly, the gear should be around 64.00. Not too bad, I think…

LOGAN ACTUATOR CO.
550 Chippewa Rd
Harvard IL 60033
USA
Tel (815) 943-9500

 

[Shiseiji]

If you raise or lower the lever, the gears never engage,...that's the problem.

Rock, can you take a second picture of the "stop bracket"? In the illustration I posted and the parts diagram below there is a long slot in the Stop Bracket P/N LA-517.

To lift the gear into position, three (3) bolts need to be loose.



EDIT:

1. Bolt 052 on the Stop Bracket
2. Bolt 038 on the Change Gear Bracket (banjo)
3. Stud LA-786

Sorry, I don't think we thought to mention needing to loosen the idler gear. The things we forget. Sorry. Maybe that is the rest of the problem.

The stud holds on both the idler gear and the gear used as a spacer (a place to store the thing). No need to loosen it and is counter-productive to loosen the nut. Note the 19XX manual doesn't show a stud head, it shows a grease fitting. I don't have a 9XX manual to check.

When the stop bracket is pulled up and the idler gear is slid on the Change Gear Bracket/banjo, the diagram below is pretty accurate on where the Stop Bracket will be. When the idler gear is in position, there should be a fair amount of the slot above the bolt head. If yours is solid, no slot, that is the problem. The wrong stop bracket is installed.

EDIT: Revised the marking on the 19XX parts below. I've circled the two (2) bolts and the idler gear stud that need to be loose to slide the idler gear on the banjo into contact with the stud gear. Note the 19XX manual I have doesn't show the LA-785 idler gear assembly idler gear center bolt/stud you have.





EDIT: Both 8XX & 18XX, 19XX & 19XX early model lathes shipped with 24 tooth stud gears and 48 tooth screw gears.
Per Scott Logan: "prior to S/N 67839, all 10” and 11” lathes with a QC Gearbox used the 24T Stud Gear. So that would include all 800 and 900 Series with the QC Gearbox.
After S/N 67839, they used the 36T Stud Gear."

Check the QCGB table on your own lathe to see if the table is for a 24 or 36 tooth stud gear train. Also "In any case, as long as the Stud Gear has half the number of teeth as the Gearbox Gear (or the same number for the coarsest threads), the gear ratio will be correct."





EDIT: The 24 tooth stud gear threading table from an up to S/N 67839 lathe manual. 8XX/18XX & 9XX/19XX would use the same table though the banjo etc are different part numbers..



EDIT: The 36 tooth stud gear threading table from an after S/N 67839 lathe manual. 8XX/18XX & 9XX/19XX would use the same table though the 9XX/19XX banjo etc are different part numbers.



Rock, what table is on your QCGB?

 

[Shiseiji]

Removed duplicate information.

 

[Shiseiji]

EDIT: Deleted duplicate information.

 

[Shiseiji]

It looks like you just need to adjust the banjo to achieve proper engagement of the gear train. Loosen the circled socket head cap screw and rotate the banjo assembly upward.
View attachment 482149

There are three that must be loosened. I missed #2 below too.

1. The idler gear under the white stud gear so it can slide in the slot on the banjo and up into contact with the stud gear.
2. The banjo you have circled
3. The stop bracket nut just to the left of the stud gear so the pin will slide up with the banjo.

 

[Rock]

Rock, can you take a second picture of the "stop bracket"? In the illustration I posted and the parts diagram below there is a long slot in the Stop Bracket P/N LA-517.

To lift the gear into position, three (3) bolts need to be loose.

View attachment 482541

1. Bolt 052 on the Stop Bracket
2. Bolt 038 on the Change Gear Bracket (banjo)
3. Nut LA-786 on the idler gear so the gear can slide on the Change Gear Bracket/banjo up into contact with the stud gear.

Sorry, I don't think we thought to mention needing to loosen the idler gear. The things we forget. Sorry. Maybe that is the rest of the problem.

Note the nut has a Logan part number because it isn't a standard nut to hold on the idler gear and any gear used as a spacer (a place to store the thing). When the stop bracket is pulled up and the idler gear is slid on the Change Gear Bracket/banjo, the diagram below is pretty accurate on where the Stop Bracket will be. When the idler gear is in position, there should be a fair amount of the slot above the bolt head. If yours is solid, no slot, that is the problem. The wrong stop bracket is installed.

I've circled the 3 (three) bolts that need to be loose to slide the idler gear on the banjo into contact with the stud gear.


View attachment 482520


The Logan 8XX lathes have a different spindle gear (circled), that's why they have a 24 tooth "stud gear" vs. the 36 tooth used on the 9/19XX lathes. I learned the 19XX series also use a 36 tooth stud gear.
Sadly, the 9XX manual appears to have has an 8XX threading table in it! It shows no 36 tooth set-ups. Now that is something to research!!!
I wonder if that's why you appear to have that nylon 24 tooth gear??? Can you give us a picture of the threading/feed table on your QCGB?

View attachment 482523


The wrong threading table from the 9XX manual.

View attachment 482524

Found on the internet (Lost Creek Machine, a good place of business IMHO) the correct 9/19XX thread/feed table with a 36 tooth stud gear. Rock, what table is on your QCGB?

View attachment 482545

Actually, after looking at the photo's you sent....I now realize that the chart for the feed table would list the number of teeth that is suppose to be on the stud gear. (I feel like an idiot,...guess I just forgot) It's a lil late tonight, but I will take a pic of my feed table tomorrow and put it on here.

 

[Shiseiji]

Actually, after looking at the photo's you sent....I now realize that the chart for the feed table would list the number of teeth that is suppose to be on the stud gear. (I feel like an idiot,...guess I just forgot) It's a lil late tonight, but I will take a pic of my feed table tomorrow and put it on here.

No worries. I am great user of the phrase "Well, now that's a Blinding Flash of the Obvious (BLUF)."

 

[Shiseiji]

I asked a poorly worded question on the forum Scott Logan moderates. I then deleted it because it was poorly worded, even though I knew many would receive the message. Scott did receive the message and provided two pieces of information to my bad question.

1. "Prior to S/N 67839, all 10” and 11” lathes with a QC Gearbox used the 24T Stud Gear. So that would include all 800 and 900 Series with the QC Gearbox. After S/N 67839, they [all] used the 36T Stud Gear"
2. " . . . as long as the Stud Gear has half the number of teeth as the Gearbox Gear (or the same number for the coarsest threads), the gear ratio will be correct."

From the Logan Lathe site: S/N 64400 - Change from 800 & 900 Series Flat Belt Drives to 1800 & 1900 V-Belt Drives. The change did not correspond with the model number change.

Summary.
The QCGB will show what the lathe shipped with.
Either a 24 or 36 tooth gear can be used as long as the stud gear and gearbox gear are 1:2. 24 & 48 or 36 & 72. Makes sense when put that way.
I believe I have a 24 & 48 mounted.

A reminder that the size of the idler gear between the stud gear and gearbox gear is irrelevant.
All three bolts that hold the idler gear must be loosened to put the idler gear in contact with the stud gear and the gearbox gear. The idler gear is mounted in a slot allowing the idler gear to slide to account for different stud or gearbox gears.
The gear on the outside of the idler is kept there as a "storage location" on the lathe. Any gear could be used.