The 222-107 is a non-gear grooved wheel for the traction tire, one per loco on the 2-axle powered 2024(222-101 type motor except double wound field instead of single). The non-grooved non-gear wheel is the 2243-33, and the two geared wheels are 600-137.
The 634 has only one geared axle, with a 222-107 non-gear grooved wheel for the traction tire and three non-grooved non-gear wheels - 2243-33 - two of them with spacers behind them to take up the space on the axle normally occupied by the depth of the gear surface.