American Flyer 312 drive issue

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  • Member since
    January, 2012
  • 236 posts
American Flyer 312 drive issue
Posted by rrswede on Wednesday, May 02, 2018 12:19 PM

I recently received assistance from a forum member regarding a AF 325 tender I had volunteered to repair. The owner has now asked if I would get a model 312 operational. My knowledge of AF is far more limited than for Lionel pre and post war equipment and I need more help.

After cleaning, lubricating and rewiring, the motor, chuffer, smoke unit and lamp all functioned. The motor was then reinstalled in the locomotive shell with the wheels properly quartered and with the side rods and balance of the running gear also installed. When power was applied, the motor operated as it should, forward, neutral and reverse. However, the driving motion was herky jerky, like the drive wheels were not rotating in unison. Upon manual inspection, it appeared the front pair of wheels had a great deal of slop in them. Is that normal? They are not gear driven like Lionel wheels and I am thinking that at operating speed, they hesitate in their rotation and once forced to rotate, create the herky jerky motion.

I removed all of the running gear and inspected the side rods comparing them to the Ebay photo, below. The photo indicates the hole at one end of the side rod is circular and the other end is somewhat slotted. Which end is fastened to the front wheels? The circular hole or the slotted hole? 

I can visually distinguish the circular hole from the slotted hole on the locomotive I am servicing but both are either worn or have been altered. Both ends are slotted, with the slot at one end being bigger than at the other end. Can normal wear create this distortion?

Not realizing the holes on the side rods were supposed to be different, I refitted them to the motor both ways but still experience the slop and herky jerky movement when power is applied to the motor. Should new side rods get rid of the slop and herky jerky movement?

Thank you, swede



  • Member since
    July, 2003
  • From: North Texas
  • 4,942 posts
Posted by wrmcclellan on Wednesday, May 02, 2018 5:46 PM

swede - there are many locos that use a "loose" side rod to account for slop in the quartering of the drivers - particularly on locos where all drivers are geared.

I would double check your quartering as it is pretty important to get the ungeared drivers to spin smoothly. 

Also check that one of your drivers has not "spun" on its axle after you quartered and mounted it. If it has you can use Loctite red to secure it. Note red is pretty permanent. Anytime I have had a jerky motion after a major repair it turned out to be an unquartered driver.

Regards, Roy


  • Member since
    December, 2001
  • From: Austin, TX
  • 9,786 posts
Posted by lionelsoni on Thursday, May 03, 2018 11:43 AM

Quartering does not need to be anywhere near exact, but it must be the same on all axles.  The Lionel "General" locomotives, for example, have no quartering at all, but still run just fine.  If there are axles driven by the side rods only, there must be some quartering, but it still may be approximate.

Most American prototype locomotives had the right side leading the left side, except for the "Standard Railroad of the World", the PRR, which used left-side lead.

Bob Nelson

  • Member since
    January, 2012
  • 236 posts
Posted by rrswede on Thursday, May 03, 2018 3:06 PM

Thank you for the responses Roy and Bob. The two rear wheels of this locomotive are driven by a helical gear meshed with a matching gear on the motor shaft. The other two sets of wheels are driven by the side rods. 

I have quartered quite a few Lionel motors and sometimes I have been off by an axle spline or so. Never have I experienced a binding issue. The quartering on this locomotive was not perfect, either, but I thought it would be fine, especially since 4 wheels were going along for the ride. 

This morning, I requartered the main drive wheels, reinstalled the side rods and manually rotated the motor and drive wheels, checking for any binding. There was none, but there still was quite a bit of rotational play in the front and middle sets of wheels. When a small amount of power was applied, the wheels rotated as they should, forward and back, with no binding. The last check was at full power and, again, no issues.

This was a first for me. I honestly did not believe quartering on this locomotive could be so finicky. Another lesson learned the hard way.

Thanks very much, swede


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