Naval Torsionmeter System

Datum Electronics Series 420 Marine Torsionmeter System provides an accurate tool to assess and monitor propeller shafts on ships by measuring shaft speed, torque and power. This Torsionmeter System was originally designed for use on the Royal Navy Hunt and Sandown Class Vessels. Later variations have been provided for the Royal Australian Navy, Korean Navy and the Indian Navy. Naval Torsionmeter Shaft Powermeter

TESTED TO DEFSTAN  & MIL Specifications

The Marine Torsionmeter System had to be approved and conform to UK Royal Navy Defstans and US MIL standards . The Series 420 system has been through rigorous MOD and MIL testing programmes for use on board vessels in services with the UK Royal Navy, Royal Austrailian Navy, Indian Navy and other naval ships worldwide. The Series 420 has been tested and verified in a number of marine conditions including, Shock & Vibration, Heat & Hummidity, Salt Atmosphere and Water Ingress. Verification has been independently conducted at accredited UK and US test house.  It is the ultimate system for the harshest of environments: DEFSTAN 59-41, 61-5, 08-123 (NES 1004), MIL901D

Single or Multiple Shaft Measurement Systems

The Datum Electronics Series 420 Torsionmeter System can either be configured for a single shaft system or for multiple (2,3 and 4) shaft systems to provide highly accurate non-contact torque measurement of shaft torque, speed and power.

System Setup

The Series 420 Marine Torsionmeter System includes a shaft Unit which is fitted to the ship shaft to measure torsional strain and rotational speed. A separate stator unit is then fixed inline with the shaft and transmits the data off the shaft to the control unit.
A Control Unit to provide power to, and take data from, the shaft units, to calculate calibrated torque and shaft power (as a function of measured torque & speed). The Control Unit also records & displays accumulated running hours for each shaft.
An optional Remote Display Unit to display, Torque, Rotational Speed (and direction ‘AHEAD’ or ‘ASTERN’) and Calculated Power from Both Shafts.

Marine Torsionmeter Shaft Specifications

The Series 420 Marine Torsionmeter System fits ship shaft diameters between (160mm - 1100mm). The shaft installation comprises a standard stator unit that provides power to the on-shaft electronics and conditions the output signals. The stator housings are manufactured to cater for a range of shaft sizes.
  • Size 1   -           shafts 160mm – 250mm
  • Size 2   -           shafts 250mm – 350mm
  • Size 3   -           shafts 350mm – 500mm
  • Size 4   -           shafts 500mm – 650mm
  • Size 5   -           shafts 640mm – 800mm
  • Size 6   -           Shafts 800mm – 1100mm

Marine Torsionmeter Installation

The Torsionmeter System has a shaft installation supplied as a rotor sub-assembly and a stator sub-assembly. The installation onto each shaft comprises a dual bridge strain gauge installation. The installation of the rotor is followed by the installation of the stator. The rotor sub assembly is split into two halves and bolted over the strain gauge installation. The rotor houses the rotor electronics module, acts as a carrier for the rotor coil and physical protection for the strain gauges. The shaft rotor and stator are separated by an air gap of up to +/-12mm to allow for fitting tolerances and shaft movement relative to the stator mountings. The Control Unit is supplied as a complete assembly; it requires four physical mounting points for easy installation and connection to the shaft units, ships control systems, logging equipment and remote displays. The optional Remote Display Units are supplied as a complete assembly, with four physical mounting points.

Accurate Measurement of Shaft Performance

The Datum Electronics Series 420 Marine Torsionmeter System accurately measures the on-shaft torque (kNm), speed of the shaft rotation (rpm) and the power (kW) that is going through the shaft. The data is transmitted from the shaft in a digital format that can be processed and scaled off-shaft. The data transmitted contains the torque level, the shaft speed and diagnostics data such as the on shaft voltage and power. The System provides actual data on the power delivered that can be compared with the expected design performance, together with ongoing data, that will indicate any changes to this expected performance level. Condition monitoring of a system of this type is important to any modern day vessel. Being able to accurately measure and record the ships power and speed data can help towards determining equipment condition and efficiency. It’s a pro-active measure with the specific purpose of improving performance and efficiency through a ship transmission system.
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Measures Shaft Torque (kNm) Shaft Speed (rpm) Shaft Power (kW)
Installed directly on ship shaft
Non-Contact Transmission System
Simple Robust Design
Designed to fit variable size ship shafts
Single or Dual Shaft Applications