The things you should know
What if there was a resilient mount that:
- has superior isolation caracteristics
- has no creep (permanent setting under load)
- is not sensative to mineral oils
- has a long life time
- is dimensionally interchangable
- has different stiffnesses to match the needed capacity
- is available in generator and propulsion execution (height adjustable)
- can be delivered from stock
This sounds too good to be true..
Meet the CR1-H!
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New Lo-Rez “Series” Steel Spring Couplings with lower Torsional Stiffness Ratings
The new Lo-Rez `’Series Spring” steel spring couplings feature a double row coupling with the two spring rows are arranged in series. The torque is carried from one spring row to the second through an intermediate transfer plate (shown in blue). The resulting overall torsional stiffness of the coupling is reduced to one half the single row rating at the same torque. Preliminary series spring coupling selection can be made using the coupling information in the Lo-Rez `Steel-Spring Flexible Couplings Brochure”, online at www.lo-rez.com. For example, an excerpt from the brochure for a standard Lo-Rez Model H coupling is shown below:
The standard “97.5/1.57” coupling highlighted in yellow carries a torque of 11,000 Nm and has a torsional stiffness of 177,000 Nm/rad. The new series arrangement would also carry a torque of 11,000 Nm, however the torsional stiffness is reduced to 88.500 Nm/rad. The axial, radial and angular stiffness are also reduced by half. The transfer plate adds an extra inertia element to torsional vibration models (typically mid-value of the coupling halves), while the cover is longer than the standard. The axial width is slightly more than double the standard single row coupling width.
ExaktAlign AB contributes to Crowley’s new builds
‘El Coqui’ and ‘Taino’
ExaktAlign AB was asked by Crowley to be part of a team of specialists performing construction supervision on the newbuildings numbers 135 (El Coquí) and 136 (Taino) at VT-Halter Marine Inc., in Pascagoula, Mississippi in the United States.
The ships, which run on liquefied natural gas (LNG), are state of the art ConRo (combination container – roll on, roll off) vessels that will sail in the trade between Jacksonville, Florida and Puerto Rico. These are the first ships of their kind to run on LNG fuel, which contributes to significantly cleaner exhaust emissions. The propulsion of each ship is provided by a MAN 8S70ME main engine, which is driving a Wärtsilä Fixed Pitch Propeller.
ExaktAlign’ s was present in the shipyard during the installation phase of the propulsion machinery to ensure each engine was installed properly.
ExaktAlign solves vibrations problems
MY Ocean 7 suffered from severe vibration proplems when sailing at high speed. ExaktAlign was hired to investigate the alignment of the propulsion installations during the upcomming docking of the vessel in the UAE. During the alignment survey was concluded that the PS propeller shaft was sightly bend. Furthermore, it was concluded the both the gear boxes as well as the main engines were misaligned. ExaktAlign was able to straigthen the shaft in the workshop of the shipyard.
Originally, the machinery was chocked by means of epoxy. Therefore it was not possibe to adjust the alignment of the driving components. It was decided to install the machinery on RotaChock adjustable steel chocks, to make it possible to re-adjust the position of the engines and gears to compensate for future setting of the resilient mounting (creep of the rubber).
Originally, the ship was equipped with LIPS branded fixed pitch propellers. During a scan of the pitch on the pressure side, it was concluded that the pitch deviated too much. ExaktAlign organized the repair of the propellers, in cooperation with Plug&De Boer in The Netherlands. The scope of the repair consisted of the repair of the pitch, static and dynamic balancing and finally polishing to ISO-class 1.
When the propellers were mounted again, the vessel was launched. During the sea trials, satisfactory vibration levels were measured.