19
APPENDIX 1
Type of Coupling
Allowable Gap (G)
(mm)
Rigid Coupling
G = 0.0005 D
All other types
Please see appropriate Installation and
Maintenance Manual for coupling type fitted.
The permitted angularity error is as follows:
Table 5
Note!
D is the diameter (mm) at which the gap is measured.
Errors of Eccentricity
The procedure for measuring eccentricity is precisely analogous to that used for angularity. In this case, however, the
measurements are taken in a radial direction and the most convenient and accurate means of doing this utilises a dial
indicator suitably clamped to one half coupling, and bearing on the hub or flange of the other, as shown in Figure 4
and Figure 5 on Page 22.
Care however must be taken to ensure the support for the dial indicator is sufficiently rigid to prevent the weight of the
indicator from causing deflection and, in consequence, inaccurate readings. Extra care should be taken where taper
roller bearings are fitted to ensure that alignment is checked with shafts in mid-point position and a final check made
with the unit at operating temperature.
The permitted eccentricity error which can be accommodated in addition to that of the angularity error is as follows:
Table 6
SPECIAL NOTE CONCERNING RIGID COUPLINGS
In lining up elements involving rigid couplings it is important that no attempt is made to correct errors of alignment or
eccentricity greater than those above by tightening of the coupling bolts. (This applies when the system is cold or at
operating temperature). The result is misalignment and the setting up of undue stresses in the shaft, coupling and
bearings. This will be revealed by the springing apart of the coupling faces if the bolts are slackened off. A check on the
angularity of a pre-assembled job, after bolting down, can be obtained in the case of rigid couplings by slackening off
the coupling bolts, when any misalignment will cause the coupling faces to spring apart. This check may not, however,
reveal any strains due to eccentricity owing to the constraint restrain imposed by the spigot.
Type of Coupling
Allowable Eccentricity
(mm)
Rigid Coupling
0.025
All other types
Please see appropriate Installation and
Maintenance Manual for coupling type fitted.
Summary of Contents for BS 40
Page 1: ...Series BS Installation Maintenance ...
Page 2: ...2 ...
Page 20: ...20 APPENDIX 2 Alternative Shaft Fixing Methods ...
Page 24: ...24 APPENDIX 4 Ventilator Position for BS40 BS71 ...
Page 25: ...25 APPENDIX 5 ...
