Pulsafeeder Pulsalube 8 GS Ultra Operation & Maintenance Manual Download Page 146

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DRIVESYSTEMS

HOLLOW SHAFT WITH

SHRINK DISC

RETAIN FOR FUTURE USE

1. Shrink disc design concept

A shrink disc option is adaptable to many NORD hollow-bore
reducers. The shrink disc applies a high-capacity, zero back-
lash, interference ﬁ t to the driven machine shaft. The dou-
ble tapered inner ring converts most all of the screw clamp-
ing load into radial contact pressure, as the outer clamping
discs are pulled together by proper tightening of the locking
screws. As the inner ring is contracted, the clearance between
the customer solid shaft and reducer shaft is absorbed.

• In their relaxed state, shrink discs provide a generous
assembly clearance, thus eliminating the typical assembly
and disassembly challenges of using interference ﬁ ts.

• Shrink discs also reduce solid machine shaft stresses by
eliminating the need for shaft keys and keyways.

• When properly applied, high shrink ﬁ ts help eliminate
shaft fretting corrosion and allow for easier shaft mounting
and

dismounting.

TAG:

Shrink Disc Type

& Bolt Torque

Reducer Shaft

Customer Solid Shaft

Locking Screws

Outer Clamping

Discs

Inner Ring

(Ferrule)

Do Not

Lubricate!!

2. Solid (machine) shaft design guidelines

Always use a solid shaft material of adequate strength and
apply proper shaft ﬁ ts in order to establish adequate clamp-
ing force during assembly and assure proper shaft release
during disassembly.

• Use solid shaft material with yield strength of at least
52,260 psi (360 N/mm

•  The solid machine shaft should be machined according to
  ISO 286-2, Class h6 ﬁ t tolerances, with a shaft ﬁ nish of 125
  micro inches (3.2 μm) or smoother, per Table 1.

• The solid machine shaft must extend the full length of the
reducer hollow shaft.

STOP

HARMFUL SITUATION

STOP

Contact NORD when using a shrink disc in an application
where the shrink disc connection must simultaneously
transmit torque and thrust.

3. Safety

WARNING

• The supporting solid shaft or driven machine shaft must
be of adequate size and strength to withstand normal
operating loads and peak loads without damage to
itself or any of the system components.

• The transmissible torque and the gripping capacity of
the shrink disc may be reduced if shaft tolerances or
clearances are larger than speciﬁ ed.

• Excessive tightening torque can result in permanent
deformation of the inner ring and the reducer hollow
bore, making disassembly very difﬁ cult. Do not over
tighten the shrink disc to compensate for excessive
clearance between the machine shaft and reducer bore.

• Observe the published ratings and safety factors
  for both the reducer and shrink disc. Overload
  conditions or excessively high torque can cause the
  shrink disc connection to slip. In extreme cases localized
  galling or welding of components may occur.

4. Shrink disc shaft tolerances

Recommended solid shaft tolerances and reducer bore toler-
ances are shown in the table below.

Table 1: Shrink disc shaft tolerances

Above &

Including

ø [in]

To &

Including

ø [in]

Solid Shaft

Tolerance

ø [in]