Page 285 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Gear and Coupling Best Practices Best Practice 4 .10
manufacturers use similar arrangements. There are some slight required range from 103,000-206,000kPa (15,000-30,000
differences which are: PSI) depending on shaft dimensions, coupling dimensions
Hydraulic oil enters the coupling hub and not the shaft. and shrink fit.
Figure 4.9.2 shows a nut which is manually turned to push the 11. When coupling is on shaft correct amount, do not remove
coupling axially. dial indicator but reduce pump pressure to zero and back
The basic coupling mounting procedure is as follows (al- off hydraulic tool slightly. Observe that dial indicator does
though readers must refer to the specific vendors’ instruction not move before removing tool.
book for the exact procedure):
Promptly assemble shaft end coupling nut.
1. Clean shaft end and coupling bore with light oil. Measure between shaft end dimension (BSE) to ensure it is as
2. Remove all ‘O’ rings from shaft end and coupling. stated on coupling drawing before assembling coupling
3. Lightly blue the coupling hub. spacer. If this dimension is not correct, consult instruction
4. Push coupling on shaft without ‘O’ rings and tap hub with book and O.E.M. if necessary before taking corrective action.
wood to ensure tight fit. Under no circumstances should coupling spacers be added
5. While hub is on shaft, index coupling hub axial position unless allowed by the coupling manufacturer or should
relative to a machined surface on shaft (usually shaft end). equipment axial shaft position be changed without O.E.M.
6. Remove hub and confirm contact area of blue is a minimum consent.
of 85%. If not, correct as required. When coupling is properly assembled check alignment using
7. When coupling contact of 85% is confirmed, clean shaft and ‘reverse dial indicator procedure’. NOTE: For coupling
coupling hub and install shaft and coupling ‘O’ rings. removal, consult vendor’s instruction book. Under no
8. Hand push coupling on shaft to indexed position in step 5. circumstances should coupling be pulled or heated. Usually,
NOTE: It may be necessary to use pump since ‘O’ rings hydraulic pressure required for removal will be higher
can provide significant resistance to movement. (5-10%) than that required for assembly. If the value
9. With hub at indexed (zero drive) position, use hand pump required exceeds 241,000kPa (35,000 PSI), do not proceed
to push coupling axially to value noted on coupling drawing. until consulting O.E.M. for additional options concerning
10. Coupling drive must be within tolerances noted. NOTE: removal.
Pump pressures will be high. Be extremely careful when
connecting pump and tubing. Be sure to secure pump so Incorrectly mounting a hydraulic coupling can cause
that hand jacking cannot break tubing. Pressures typically catastrophic coupling and/or shaft end failure.

Best Practice 4.10Practice 4.10
Best
Correct hydraulic coupling hub installation will ensure Lessons Learned
trouble free operation and optimum unit safety and Installing a hydraulic coupling with hub and shaft (if appli-
reliability. cable) “O” rings installed will result in insufficient coupling
Always install shrink fit couplings first without ‘O’ rings. shrink and can cause hydraulic coupling slippage.
Measure proper (80% contact) and standoff of coupling hub to shaft
end. Benchmarks
Assemble ‘O’ rings to obtain previous standoff.
This best practice has been used since 1975, and has resulted in
Drive (push) coupling to specified axial movement.
trouble free hydraulically shrunk coupling installations and coupling
removals.
See procedure contained in B.P. 4.9 Supporting Material for further
details.

B.P. 4.10 SUPPORTING MATERIAL
Please refer to material in B.P. 4.9.

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