AAF International Type W RotoClone - Manual (Page 9)

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4.9 Replacement of Shaft, Impeller or Water Cone
Removal of the shaft, impeller, or water cone requires access to
the front of the scroll. This is most easily accomplished by removing
the inlet piece and scroll inlet cone. The water piping should be
disconnected before removing the inlet sections. The water cone
should be marked to indicate the bolt hole locations in relation to
the scroll, before removal. The old water cone can be used to match
mark the replacement water cone, which comes undrilled. Note the
distance from the back of the impeller to the scroll before removing
the impeller. The impeller is fastened to the shaft by a taper lock hub.
It is easiest to remove the impeller from the shaft by using a wheel
puller, after unbolting the hub; or one can reinsert the hub screws into
the unused holes in the hub to “push” the shaft off of the hub.
However, on units that have been in service for years, this method
may not provide the necessary force to “break” the hub away from the
shaft, and the wheel puller will be necessary. Finally, the bearings and
driven sheave are taken off and the shaft can be removed.
Reinstallation is the reverse of removal. The shaft is replaced and the
bearings and driven sheave tightened back onto it. New set screws
should be used, when single piece bearings are supplied, as the old
ones will most likely have blunted ends that can no longer adequately
Shaft
Front Bearing
Assembly
Shaft Seal
Shaft Seal
Housing
Bearing Bracket
RotoClone Back Sheet
Taper Lock Hub
Disc Plate
Lock Bushing
Key
Hub Cap
Hex. Head
Cap Screws
Figure 5 — Construction details of Type W RotoClone Shaft Assembly showing heavy duty bearings, oversized shaft, watertight shaft seal, laminated impeller disc,
and cast iron hub with taper lock for easy impeller removal.
Shaft Assembly — Arrangements A and D
secure the collar to the shaft. Be sure to tighten the set screws to the
proper torque as recommended by the bearing supplier (or contact
AAF for recommendation). The impeller is reattached to the shaft,
but the taper lock hub screws are not tightened yet. All old gasketing
material should be removed from the scroll and water cone. A new
water cone gasket should be cemented to the water cone. The water
cone is then reattached to the scroll using the match marks to orient
it in the same position as the original. The impeller is then checked
for proper distance from the water cone edge using Figure 6 and
the Table on page 10.
The taper lock hub screws are tightened After confirming the proper
position of the impeller. Note that the impeller may shift as the hub is
tightened onto the shaft; the impeller position should be checked while
tightening the hub and repositioned as necessary. A wooden block
and hammer can be used to “tap” the impeller back if required.
Recheck the impeller position and rotate the impeller to insure that
it turns freely, once the impeller is locked onto the shaft. The inlet
pieces and piping can then be reattached. A waterproof caulking/
gasket is used between the inlet flanges; remove any old material
before reinstalling, and be sure to encircle bolt holes with caulk,
or leaks may result.