Worm Gear Replacement

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Smudge617

Smudge617

Well-Known Member
I have a Athearn SW7 Switcher but minus the worm gear, service sheet says part#40020 which I've having trouble in sourcing, so my question is can I use a #31428 worm gear ?
 
I can send you a heap of worms if you like @Smudge617. Not sure how alive they will be when they get though ... :confused:

Oh, not that type of worm huh ... okay, in that case - sorry mate don't have a clue sorry :( What is the difference between the two gears though? Would it be financially viable to buy one of the #31428 gears and see if it will fit?

I'm just guessing that there will be some sort of a difference between the two. Can't logically think of any other rational reason for making two different gears for the same engine?
 
Smudge: I suspect that there will be a difference between the 2 gears. Specifically teeth pitch and depth. Either needs to match the gears in the gear tower almost exactly or you are gonna have binding and probably noise. Could be that the shaft diameter is different also.

Later
 


wombat457 said:
I can send you a heap of worms if you like @Smudge617. Not sure how alive they will be when they get though ... :confused:

Oh, not that type of worm huh ... okay, in that case - sorry mate don't have a clue sorry :( What is the difference between the two gears though? Would it be financially viable to buy one of the #31428 gears and see if it will fit?

I'm just guessing that there will be some sort of a difference between the two. Can't logically think of any other rational reason for making two different gears for the same engine?
Click to expand...
As far as I can see the only difference is that one is brass and the other plastic
 
ctclibby said:
Smudge: I suspect that there will be a difference between the 2 gears. Specifically teeth pitch and depth. Either needs to match the gears in the gear tower almost exactly or you are gonna have binding and probably noise. Could be that the shaft diameter is different also.

Later
Click to expand...
That's what I'm worried about, but apart from one being plastic and the other brass, visibly (on a photo) I can't see any difference
 


Smudge: did a quick check on evilbay - search for 'Athearn worm gear', or 'Athearn 40020'. Found one auction with 4 gears - $15 including shipping. Did not find any 31428's though. Don't know what shipping would be across the pond.

Later
 
ctclibby said:
Smudge: did a quick check on evilbay - search for 'Athearn worm gear', or 'Athearn 40020'. Found one auction with 4 gears - $15 including shipping. Did not find any 31428's though. Don't know what shipping would be across the pond.

Later
Click to expand...
Thank's I'll take another look.
 
Smudge617 said:
I have a Athearn SW7 Switcher but minus the worm gear, service sheet says part#40020 which I've having trouble in sourcing, so my question is can I use a #31428 worm gear ?
Click to expand...
Smudge I have a dumb question Where did you get that part number #31428 I only find #34128
The 34128 is a direct replacement for #40020 It's just plastic instead of brass Hence the "High Performance" I don't think it will make any difference how the engine runs maybe less gear noise ??
That 40020 was used in just about all blue box athearn engines
 


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