This Cincinnati GEM water pump chain sprocket with shaft is the drive-component replacement for the chain-driven Cincinnati GEM pump system. The sprocket converts the rotational motion of the pump’s hand crank into linear travel of the bucket chain that lifts water up the well casing — making it one of the most-stressed wear components in the system.
Over time, sprocket teeth wear, the shaft develops play, and the assembly stops engaging the chain reliably. At that point, the pump stops working effectively and needs the dedicated replacement sprocket-and-shaft assembly to return to service. Buying the matched assembly rather than separate parts ensures the sprocket and shaft are properly aligned and dimensioned for the original Cincinnati GEM specification.
For households operating Cincinnati GEM pumps for off-grid or backup water supply, this kind of major-component replacement extends the pump’s working life essentially indefinitely. Pair with replacement pump buckets (sold separately in the Lehman’s catalog) for a complete chain-and-sprocket rebuild that returns the pump to like-new performance. Lehman’s catalog selection.
