Page 298 - Machinery Component Maintenance

280 Machinery Component Maintenance und Repair

B. End-dr ive adapter
mounted on rotor shaft;
match-marks in line.

C. End-drive adapter
indexed 180' on rotor
shaft; match marks on
opposite sides.

0 Indicates void where no key exists

Figure 6-23. Full-key method.

Basic Design Criteria

As is the case with most balancing machine tooling, an arbor should be
as light as possible to have minimum effect on machine sensitivity. This
is particularly important when using a soft-bearing machine. At the same
time, the arbor must be rigid enough not to flex or bend at balancing
speed.
For ease of set-up in a horizontal machine, the arbor should be de-
signed so that the rotor can be mounted near the center (Figure 6-24).
Where this is not possible, perhaps because the rotor has a blind or very
small bore, the rotor may be mounted in an outboard position (Figure
6-25). If the center-of-gravity of the combined rotor and arbor falls out-
board of the machine supports, a negative load bearing is required on the
opposite support to absorb the uplift.
A light push fit between arbor and rotor will facilitate assembly and
disassembly, but may allow the rotor to slip during acceleration or decel-