couplings & dampers
an outer diameter of 3,360mm. “This seems large but, compared with the engine size, these dampers are still small. The advantage of using a Geislinger damper is that the shipowner can avoid a barred speed range – in times of slow steaming this can result in actual savings on operation costs.” MAN Diesel has manufactured its own dynamic damper for many years – the Hülsenfeder Dämpfer for its four-stroke engines – which works on a similar principle
to the Geislinger damper. Its spring packs are C-shaped and tend to have higher maintenance due to the friction between the springs which is necessary for damping. Per Rønnedal, MAN Diesel’s senior manager of marine low speed engines, says the company’s general policy is to design its two-stroke engine as cost effectively as possible, and avoid torsional dampers unless required for specific reasons. “As such, our 11 and 12 cylinder marine two- stroke engines are normally equipped with
a damper in order to reduce the stresses in the crankshaft. For most other engines, the question of whether to select a torsional damper is a matter of general shafting design and optimisation. A lot of parameters go into the decision, both relating to engine operational aspects and to classification rules and shaft design options available in the given case.’’ MAN Diesel is also moving towards outsourcing the research and development and the production of torsional dampers.
Versatile coupling compensates for high displacement
KTR Kupplungstechnik’s (KTR) markets a coupling solution suitable for multiple applications: the double-cardanic Radex-N composite. Its extremely stiff laminas, made from stainless spring steel, allow the coupling to compensate for high displacements with low restoring forces. This type of composite coupling has a special feature: the CFK spacer. It bridges
long distances between the driving shaft and impeller without any additional bearing. KTR recommends the use of a Rotex coupling in combination with a KTR-SI overload system for the propeller unit in an azimuth drive driven by an electric motor. This combination protects the gearbox of the propeller unit against high-torque shocks and increases the service life of the drive
Rubber link couplings suitable for high speed craft
system, especially if the steering unit collides with the seabed. An example of this is when the vessel is manoeuvring in shallow water.
KTR says that using its Clampex KTR 400 and 402 clamping sets will help keep a ship on course. These products have been developed, in particular, for high loads, high alternating torques and high torsional forces. The non-positive shaft- hub connection has been designed for large shaft diameters up to 400mm and is able to transmit much higher torques and axial forces than a positive-locking connection. KTR’s torsionally flexible Rotex shaft coupling is used on deck winches and cranes and in electric power packs in marine hydraulics. KTR’s BoWex coupling is proven on hydraulic power packs in combination with IC-engines, using the BoWex curved-tooth gear coupling as a highly flexible BoWex-Elastic or torsionally rigid BoWex FLE-PA flange coupling. Both couplings can be plugged in axially and are therefore easy to disassemble. Sometimes, a separate power source is required on board ship. This is not a problem, says KTR. With a powerful marine generator and a fail-safe coupling, Rotex and BoWex-Elastic can again be used, as they are compact and flexible, transmitting high torques and damping vibrations.
The Jaure Ixilflex coupling is bi-directional
Having been first sold to wind turbines 15 years ago, Jaure Ixilflex couplings are now being targeted for offshore support vessels, including the next generation that will be used to support offshore wind turbine installation and maintenance. The Jaure Ixilflex coupling is a
bi-directional rubber link coupling for high misalignment. The couplings first marine
54 I Marine Propulsion I February/March 2012
application was on patrol boats. Today they can also be found on fast ferries and other high speed craft. Over 11,000 Ixilflex coupling are in service. Today Jaure’s marine product portfolio of flexible couplings also includes MT gear and Lamidisc disc pack coupling. Other components like bearings, bulkhead seals and brake systems are integrated on demand.
Hydraulic coupling is a compact option
All Cedervall hydraulic flanges are designed to optimise the allowable torque offered from the prime mover, tight fitting tolerances are achieved between shafts and couplings meaning installation pressures used are as high as 1,200 bar using gearbox oil of ISO VG 100 viscosity. For hollow bored shafts a reinforcement sleeve may be needed in order to optimise the design. Hydraulic pumps and fittings are delivered upon request. For flanged couplings, fitted or hydraulic bolts are also available. MP
www.mpropulsion.com
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92 |
Page 93 |
Page 94 |
Page 95 |
Page 96 |
Page 97 |
Page 98 |
Page 99 |
Page 100 |
Page 101 |
Page 102 |
Page 103 |
Page 104 |
Page 105 |
Page 106 |
Page 107 |
Page 108 |
Page 109 |
Page 110 |
Page 111 |
Page 112 |
Page 113 |
Page 114 |
Page 115 |
Page 116 |
Page 117 |
Page 118 |
Page 119 |
Page 120 |
Page 121 |
Page 122 |
Page 123 |
Page 124 |
Page 125 |
Page 126 |
Page 127 |
Page 128 |
Page 129 |
Page 130 |
Page 131 |
Page 132