Post by harmonyards on Aug 10, 2024 1:52:33 GMT
Let’s fix the misnomers, and get a useful list of locomotives affected with gearbox woes, clear up the myths, and list the known in-field fixes that have been developed to correct the problems.
Lionel’s gearbox issues arose with the advent of the compound gearbox utilizing the Mabuchi 385 motor. We complied a list of earlier Legacy locomotives, and I’ll get that list of known possible troublemakers on this thread. This all began when I was getting requests to look at two models in particular. The legacy PRR K4, and the H10. Before we dive in, NOT ALL ARE DOOMED TO FAIL!!….Let me make that perfectly clear. Although I’ve seen quite a few that have completely failed, I’m sure the entire production run isn’t looming in failure mode.
Legacy PRR K4 & H10: The intermediate gear shaft ( mounted in the same orientation as the axles ) can exhibit wear and shift the gear cluster to one side, thus the driven worm wheel ( 1st gear on the cluster ) gets too far to one side of the worm gear attached to the motor. The worm gear therefore rides on the ragged edge of the worm wheel. Over time, this can grind away the edge of the worm wheel causing the the two gears to skip. I will add to the K4 & H10 lists of identified possible trouble makers. The non-invasive fix keeps the intermediate shaft centered under the worm gear, and prevents premature failure. The bar stock has a machined half moon bushing installed so the worm wheel isn’t dragging against the bar stock and acting like a brake shoe.
Legacy L1 & I1: The factory miscalculated the depth of the worm gear pressed onto the mabuchi 385 motor. I give the credit for the diagnosis and the fix to Norm C. In the case of these locomotives, when the locomotive is in reverse, the worm gear rides too close on the blind section of the gear when engaging the worm wheel. This can result in a jam, or a stutter. The fix is to use Norm’s 3D printed motor shim in selective thicknesses, and space the motor away from the mount so the worm gear’s blind spot can not ride on the worm wheel.
So to summarize, the problems the above locomotives can have are not really related. It’s different problems, resulting obviously in a broken model that you can’t enjoy.
Pat
The Water Level Route
Lionel’s gearbox issues arose with the advent of the compound gearbox utilizing the Mabuchi 385 motor. We complied a list of earlier Legacy locomotives, and I’ll get that list of known possible troublemakers on this thread. This all began when I was getting requests to look at two models in particular. The legacy PRR K4, and the H10. Before we dive in, NOT ALL ARE DOOMED TO FAIL!!….Let me make that perfectly clear. Although I’ve seen quite a few that have completely failed, I’m sure the entire production run isn’t looming in failure mode.
Legacy PRR K4 & H10: The intermediate gear shaft ( mounted in the same orientation as the axles ) can exhibit wear and shift the gear cluster to one side, thus the driven worm wheel ( 1st gear on the cluster ) gets too far to one side of the worm gear attached to the motor. The worm gear therefore rides on the ragged edge of the worm wheel. Over time, this can grind away the edge of the worm wheel causing the the two gears to skip. I will add to the K4 & H10 lists of identified possible trouble makers. The non-invasive fix keeps the intermediate shaft centered under the worm gear, and prevents premature failure. The bar stock has a machined half moon bushing installed so the worm wheel isn’t dragging against the bar stock and acting like a brake shoe.
Legacy L1 & I1: The factory miscalculated the depth of the worm gear pressed onto the mabuchi 385 motor. I give the credit for the diagnosis and the fix to Norm C. In the case of these locomotives, when the locomotive is in reverse, the worm gear rides too close on the blind section of the gear when engaging the worm wheel. This can result in a jam, or a stutter. The fix is to use Norm’s 3D printed motor shim in selective thicknesses, and space the motor away from the mount so the worm gear’s blind spot can not ride on the worm wheel.
So to summarize, the problems the above locomotives can have are not really related. It’s different problems, resulting obviously in a broken model that you can’t enjoy.
Pat
The Water Level Route