TT (Thrust & Torque Mounts)

General
The TT mounts are especially developed for the high-powered / low weight, close coupled engine I gearbox combinations. The unique mounting design characteristics enables to transmit both Thrust and Torque forces whilst ensuring excellent vibration isolation. The TT mounts have a linear stiffness over a wide load range varying from compression H to extension (+ I necessary to maintain the optimum isolation properties of the Mass-Spring system formed by engine / gearbox and mounts. The close-coupled gearbox reduces the engine rpm's and as a consequence, magnifies the engine torque. The reaction torque is being transferred over the TT mounts to the foundation as additional compression or extension forces which requires the TT mounts unique linear (compression I extension) stiffness to maintain the same high degree of isolation.

Specification
The stiffness ration from Vertical (Z) to longitudinal (X) is selected such to minimize displacements of the installation and connected equipment in this direction, which for instance is beneficial for shaftseals. The thrust capacity per mount, related to the actual mount load (Fl) can be taken from the capacity curves. The height adjustable TT mounts are produced in a lightweight, seawater resistant aluminum and among others feature slotted / threaded holes to secure the mounts during transportation and, or alignment of the engine installation. The castings are designed such as to protect the interchangeable rubber inserts from contamination. The central threaded stud enables easy installation and in the case of a thrust transferring application of the TT mounts; the recommended tightening torques should be kept. The TT mounts have an integrated limiter, which limits the displacements in the vertical direction to +3.1 and -11.5 mm for the TT-I mount and +3.3 and -6.3 mm for the TT-2 mount. In the horizontal direction the TT I mount is limited to + or -5 mm and the TT-2 mount to + or -3 mm. The standard rubber mix NR39 is available from 45° Sh.A up to 70° Sh.A and can be used up to 90° C continuous and 110° C peak temperature, furthermore it will ensure low creep values. The NR 11 mix is available in 45° to 75° Sh.A, which can be used up to 70° C continuous and 90° C peak temperature and will ensure higher load capacities. All TT mounts are marked with the rubber hardness derived from the individual stiffness test on one side of the top casting.

Technical Data
  1. Typical Creep
    The typical creep rate of the TT mounts will vary with compound, rubber hardness, dynamic loads, thermal loads, and strain. The typical value for the NR39 compounds will be 3% of the static deflection increase per decade. For the NR 11 compounds this value will be 4%. 48 hours after loading more than half of the total creep figure over 20 years will be achieved.
  2. Thermal Expansion
    The typical thermal expansion rate of the TT mounts will be approximately 0.01 mm / °C increase in height depending on compound, rubber hardness and strain. The expansion rate is directly related to the temperature of the rubber element.
  3. Thermo Shock
    Every temperature exceeding the latest achieved peak temperature will cause a permanent set of the mount of approximately 0.01 mm / °C in the range from 20° to 90° C. For instance the first thermal load from surrounding temperature to normal working temperature will cause an extra set of the deflected height next to the normal creep. Every time the mount temperature is raised to the normal working temperature, no extra set will occur. Once the normal working temperature is exceeded, an extra set will occur again. The permanent set is directly related to the temperature of the rubber element.

Download TT-1 Dimension Specifications
PDF Drawing of mount

Download TT-2 Dimension Specifications
PDF Drawing of mount


Download TT-3 Dimension Specifications
PDF Drawing of mount

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