Driver Thrust Bearing

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NP317
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Re: Driver Thrust Bearing

Post by NP317 »

Bill S said:
"What I always check is axle positioning with the axles in place and all the journals pushed FORWARD in the running position. This is what is important in the long run...not the frames."

I emphasize his comments. The actual axle positions relative to the frames are what count, not the frame openings.
They need to be checked for squareness. Your tests assume the axle boxes are machined correctly.
Assumptions can lead us astray.
RussN
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Greg_Lewis
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Re: Driver Thrust Bearing

Post by Greg_Lewis »

NP317 wrote: Sat Jan 22, 2022 9:31 pm Bill S said:
"What I always check is axle positioning with the axles in place and all the journals pushed FORWARD in the running position. This is what is important in the long run...not the frames."

I emphasize his comments. The actual axle positions relative to the frames are what count, not the frame openings.
They need to be checked for squareness. Your tests assume the axle boxes are machined correctly.
Assumptions can lead us astray.
RussN

Good thought. And this leads to a solution for a frame that's not right if it can't be corrected: correct in the axle boxes.
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Bruce_Mowbray
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Re: Driver Thrust Bearing

Post by Bruce_Mowbray »

Question,
Why don't us modelers incorporate "rock in the box" (hourglass shaped slots) when machining our journal box pedestal slots? This allows for tilt in the axle on uneven track. The fact that weight was added to the original design could have caused the engine to tilt to one side, thus causing the boxes to bind in the pedestal openings, maybe more so with the added weight. The fact that the axle tilted, and the boxes were restrained, could cause undue wear on the lateral faces and thrust washers.
Bruce Mowbray
Springville & Southern RR
TMB Manufacturing & Locomotive Works
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cbrew
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Re: Driver Thrust Bearing

Post by cbrew »

Bruce_Mowbray wrote: Sun Jan 23, 2022 9:29 am Question,
Why don't us modelers incorporate "rock in the box" (hourglass shaped slots) when machining our journal box pedestal slots? This allows for tilt in the axle on uneven track. The fact that weight was added to the original design could have caused the engine to tilt to one side, thus causing the boxes to bind in the pedestal openings, maybe more so with the added weight. The fact that the axle tilted, and the boxes were restrained, could cause undue wear on the lateral faces and thrust washers.
I didn't cause I do not have the tool set to repeatability cut that arc.
how would you set this up on a manual mill?
If it is not live steam. its not worth it.
Bruce_Mowbray
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Re: Driver Thrust Bearing

Post by Bruce_Mowbray »

Chris,
It's not an arc, but more of a taper that gets wider from the center out towards the top and bottom of the box. The amount is not much, 1/4" per foot on each side or roughly 1/2 degrees, with a 1/4 " flat section in the middle. The slot would end up being about .020" wider top and bottom.
Bruce Mowbray
Springville & Southern RR
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NP317
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Re: Driver Thrust Bearing

Post by NP317 »

I cut those axle box angles on both of my steam locomotives.
Work fine.
RussN
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Bill Shields
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Re: Driver Thrust Bearing

Post by Bill Shields »

As do I...and since my first loco do not put ears on the inside of the frame.
Too many things going on to bother listing them.
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cbrew
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Re: Driver Thrust Bearing

Post by cbrew »

when i ran the numbers, I didn't feel juice worth the squeeze. adding another .005 of Clearance.
i also only run ears on the outside of the boxes. with the thrust bearing between the back of the driver and the journal, everything stays put
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daves1459
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Re: Driver Thrust Bearing

Post by daves1459 »

NP317 wrote: Sat Jan 22, 2022 9:31 pm Bill S said:
"What I always check is axle positioning with the axles in place and all the journals pushed FORWARD in the running position. This is what is important in the long run...not the frames."

I emphasize his comments. The actual axle positions relative to the frames are what count, not the frame openings.
They need to be checked for squareness. Your tests assume the axle boxes are machined correctly.
Assumptions can lead us astray.
RussN
Checking the axle position with them and journals in place is a good idea. It is easy to see that no assumptions are in play. In the case of my loco, and the original subject of this discussion, there are no assumptions regarding the journal boxes. I made the journals as replacements for the originals and can assure you that the axle bore of all four journals is equal distant within a thou or two from the leading/contact face that bears on the pedestal. Any idea just how parallel and square the axles have to be?

I'd be interested in how Bill checks axle squareness with the axles in place in the journals in the frame. There is always more than one way to solve a problem. I take Biil's comments to heart and he has influenced may approach to solving the thrust bearing wear I experienced. Since the frame is foundation of the loco and almost everything related to the rolling chassis is referenced to it a survey of the frame as an assembly seems to me to be a worthwhile exercise. I should have done that way back when I started the restoration. I could have easily made any adjustments the pedestal openings at that time and modified the journals to suit with slippers.

Regarding flanges only on the front side of the journal: Of course that will work and it will work well as many have experienced. So will a slotted journals as long as the slot is wide enough to accept the axle end play.

Finally, regarding machining relief angles on the inside of the journal flange how much vertical travel on a 1 1/2" model needs to be accommodated? I've seen such angles on drawings of prototype journals.

Dave
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Bill Shields
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Re: Driver Thrust Bearing

Post by Bill Shields »

Vertical travel can only be as much as the height difference between the frame pocket and the axle box.

Cutting the angle to be more than needed hurts nothing since in reality the box is going to ride the point of the 'wedge' created.

How do I measure axle position?

Well..I jam a piece of wood behind each axle box to shove it forward.

On a rebuild, then I use either a big micrometer (for a small loco) or a large set of calipers to measure inferred center distance (knowing axle diameter).

Keeping in mind that everything has to go up and down and side to side, caliper measurements for comparison are more than close enough since I typically drill my side rods to size...allowing ample clearance for all to wander about following typically rough track.

For a new loco...I put the frame with the axle boxes clamped in the forward position -> all on its side and bore the lot in my mill....I one side and out the other.

This way...assuming the head is square in the mill..I do not have to worry about accumulated tolerances or unwanted clearances affecting the final axle positions.

Call me Fred Flintstone but it works for me..
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Santafescotty60
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Re: Driver Thrust Bearing

Post by Santafescotty60 »

I have just a silly question are you running a loop railroad the same direction could this be putting a lot of load on that driver? I like the bronze washer idea sounds good I assume these are firebox warmed journal boxes some super plastics get squishy at 500 Degrees F? McMaster Carr sells flush mounting 10-32 or 8-32 threaded oilers or Zert (Zerk) fitting for your axles you will need to center drill and cross drill the axle to lube your roller bearings. I am using heavy steam oil /gear lube or grease in those warm areas and dripping oil on the journal boxes /suspension links for up and down motion. You will need a needle grease nozzle for the grease gun or an oil can that will push the check ball to shoot the lube.
Just some ideas hope it helps
Scotty
daves1459
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Re: Driver Thrust Bearing

Post by daves1459 »

Hello Scotty and thanks for your ideas,
The railroad is a folded dog bone shape with approximately an equal amount of right and left curves..
The loco is an old time type 4-4-0 with a deep fire box that is near the axles so there is likely some heating. How much I do not know. I going to use grease to lubricate the journal needle roller bearing as I believe Bill S. and others suggested early on. Apparently you are using grease also. I have modified the axle ends to create a sort of internal cellar and a local shop will EDM a 1/16" cross hole in the hardened journal. I'll will also make a hub cap with removeable Zirk fitting. I'm still wrestling with what type of grease to use. There are dozens of wheel bearing greases. I have assumed a low temperature lithium based grease would do. Additives like graphite and molydisulphide are available. Any suggestions (from anybody)?

Dave
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