 |
|||
|
|
|||
| ||||||||||
|
|  MIL-P-17639F(SH)
3.2.6.10 When motor driven pumps of the close-coupled type are specified,
bedplates will not be required, except as otherwise specified (see 6.2.1).
Each pump shall be provided with a support for bolting to the foundation to
augment the support from the motor frame,
3.2.7 Bearings. Bearings shall be installed in each pump unit for counter-
acting (a) any unbalanced hydraulic or mechanical thrust in either direction and
(b) the fact that rolling, pitching, listing and trim, and the athwartships, fore
and aft, and the vertical distance from the pump to the ship's rolling and
pitching center may introduce loads even though the unit is in hydraulic balance
(see 6.2.1). The contractor shall calculate the resulting static and dynamic
loads on the bearings and certify that the bearings are suitable for this loading
(see 6.2.2).
3.2.7.1 Radial bearings.
3.2.7.1.1 Radial bearings may be of the hydrodynamic or rolling contact
type. If specifically approved by the design review agency (see 6.4) hydro-
static bearings may be used.
3.2.7.1.2 Except as otherwise approved by the design review agency,
rolling contact bearings shall be of the ball type in accordance with FF-B-171.
Roller bearings may be recommended if use of ball bearings is impractical. If
approved, roller bearings shall be in accordance with FF-B-185 or FF-B-187.
Rolling contact bearings shall be selected to result in a minimum B-10 life of
10,000 hours calculated in accordance with FF-B-171, FF-B-185, or FF-B-187.
3.2.7.1.3 Rolling contact bearings specifically selected for quiet opera-
tion in accordance with MIL-B-17931 shall be used for pumps for submarine appli-
cation and for surface ships where required to meet special noise requirements.
3.2.7.1.4 Hydrodynamic radial bearings may be of the fixed or self-alining
type and shall operate under full-fluid film lubrication for all operating condi-
tions, except boundary lubrication will be permitted during pump start-up and
shut-down. Where the requirement for full-fluid film operation cannot be met, a
hydrostatic bearing may be recommended by the contractor for design review agency
approval. The hydrostatic bearing shall operate without metal-to-metal contact
over the entire range of the pump characteristic curve.
3.2.7.1.5 Water lubricated hydrodynamic radial bearings shall not be
provided with lubrication grooves unless specifically recommended by the
contractor and approved by the design review agency. If a hydrodynamic bearing
design having axial grooves is recommended by the contractor, positive proof of
the direction of radial loading shall be established. The orientation of the
bearing shall be such that the effective bearing arc will not be reduced to less
than 120 degrees at any operating condition of the pump. Orientation of the
bearing shall be maintained by positive means. The effective arc is defined
herein as the continuous load-carrying surface which is symmetrical with respect
to the load vector. Release for manufacture shall be subject to verification
of the applied load direction, by experimental data, and derived from tests of
the manufacturer's own similar designs. Where the method or experimental data
are considered inconclusive by the design review agency, the recommendation
for a grooved bearing design will be disapproved.
9
|
|
Privacy Statement - Press Release - Copyright Information. - Contact Us |
Click
here for thousands of PDF manuals