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BOW-THRUSTER
type BTM
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 The Bow-Thruster (or side pusher) type BTM foresees the coupling either to a hydraulic motor or to an electric motor, connected to the vertical transmission shaft to an orthogonal axes reducer, having a strong reduction ratio, thus allowing the use of high-performance 4-vane screws, with low cavitation index.
Easy to install, it has been studied to reduce the dimensions as much as possible, and to allow a quick extraction for maintenance operations.
The possibility of a coupling with a hydraulic motor allows to carry out also other hydraulic plants for on-board auxiliary services.
The construction accuracy and the high safety factors adopted in the design of all the components allow to the BTM propeller reliability, noiselessness and very long life. |
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Hydraulic plant:
in case of hydrostatic transmission, all the components used come from primary Companies in the field. Moreover, thanks to the diesel or electric motor available, the Bow-Thruster is manufactured to operate in the range of maximum yield of the transmission.
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- The reducer:
is manufactured in carburizing steel and the spiral-gleason toothing is ground on sides. For the lubrification we recommend to use, unless different indication, oil of SAE 90 degree.
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BTM Type
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Propeller Diameter [mm]
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Propeller rev. speed
[rpm]
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Thrust
[Kn]
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Power max Input
[Kw]
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Pressure max
[bar]
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50
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380
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1200
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4.70
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38
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350
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150
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650
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650
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14.2
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110
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350
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300
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1100
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550
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28.5
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220
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350
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500
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1350
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450
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47.5
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365
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350
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800
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1500
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400
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76.0
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585
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350
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- Hydraulic fluid:
as far as the hydraulic fluid to be used is concerned, please refer to the use and maintenance manual, supplied together with the drawings for the maintenance of the unit. Of course, the hydraulic oil will be chosen according to the operating temperatures and to the hydraulic transmission used.
We deem "standard" the application which foresees uses amongst the temperatures of -25°C and +90°C.
The filtration degree will be assured by a filter having characteristics suitable to preserve the axial piston units (pump and motor). The type and characteristics will be shown on the hydraulic sketch of the circuit, together with the maintenance and replacement modalities.
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Screw:
the screw supplied in the propeller is a 4-vane screw with high developed area / disc area ratio, with no felling, so as to obtain the same thrust in both the thrust ways, with a geometry purposely studied for the tubed functioning. |
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Painting:
standard epoxy cycle.
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Test:
The test will be requested by the buyer exclusively at the time of the order, by specifying the desired Inspection Authority.
For RINa inspection there will be a 10% extra-cost. Other authorities' inspection will be separately billed after the completion of the job. |
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Dimension
of the side pusher: to select the type of Bow-Thruster to
be installed, first of all it is necessary to know the driving motor
power and the number of revolutions at which it is available,
as well as the thrust requested to the screw. Of course, to choose
such an important component, we strongly recommend to contact, at a
preliminary stage, our technical department. |
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Installation:
for a proper operation of the azimuthal stern thruster, the following simple conditions are to be respected during ship's design:
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a) the tube where the azimuthal stern thruster will be installed will have a length L at least double of its internal diameter.
This is of essential importance to allow the water flow to start and stabilize before cover the propeller.
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b) to avoid cavitation phenomena it is necessary to avoid that the tube sucks air from the surface,
the end of the tube must be put at least at 0,25 times the diameter D under the waterline.
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c)
to avoid that foreign bodies (even solids) come into
the pusher's tube, thus damaging it or compromising its optimal
operation, the bow-thruster tube should be provided with protection
grids fitted to the end of the tunnel: a correct positioning
of the grids and a proper covering factor allow to limit the obvious
reduction of the propeller's thrust.
The installation without grids may cause the entry of foreign bodies with the consequent screw vanes' and propeller's mechanic damaging. The shipyard is therefore recommended to consult our technical department for the protection grids fitting.
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d) to avoid the starts of secondary movements below the underbody
, it will be necessary to place the bow-thruster not so near the corner of the hull underbody and it will be necessary to keep a minimum distance from the bottom of at least 0.9 times the D diameter of the tube of the lower side of the same.
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TECHNICAL DRAWINGS
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Reference for the dimensions shown in the form |
Bow
Thruster: |
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