G&O Vibration Compensator

Vibration Problems? Why deal with the symptoms, when we can eliminate the source!

Gertsen & Olufsen Vibration Compensators are world leaders in eliminating unwanted vibrations and improving the performance and comfort of ships and power plants. The company specialises in the development, production, installation and sale of electrically driven moment compensators.

A Gertsen & Olufsen vibration compensator is designed to do the exact opposite of the inducer (engine or propeller) by delivering a cyclic and opposing counterforce in a specific direction at a specific time. Main engines, propellers and hulls are all having very low natural frequencies; our systems have a corresponding operational frequency bandwidth from 1to 25Hz depending of the type of compensator in question.

The system creates an opposing sinusoidal varying force and phase angle that simply outbalances the source of vibration. Two sets of counter rotating irregular masses are driven by an electric servo drive ensuring a cyclic counterforce. The two counterweights can be individually adjusted to any required counterforce – once the necessary force has been determined it will be locked in that specific position. The servo drive is synchronized with the main engine ensuring that the correct and opposing phase angle is maintained.

There are two types of compensators: The horizontal- and the vertical type of compensators. The compensators are delivered in different sizes comprising the varying size of forces required.

A complete Gertsen & Olufsen vibration compensator system comprises three main components:

The synchronising unit controls frequency and phase angle of the compensator unit, based on the measured inputs from the encoder unit.

The Compensator ensures synchronising with the main engine by means of

small mass-moments of flyweights and high torque of the servomotor.

The main engine RPM detection system detects the main engine rpm

(3.000 pulses per engine revolution) and the top dead centre (TDC) of

main engine cylinder no.: 1.

In the following we will give you a general overview of different type of vibrations induced by either main engine or propeller and some practical application examples of how to solve the problems. Generally we are working with the following different fields of vibrations;

External Unbalanced Moments
External unbalances are caused by the inertia of the rotating unbalanced masses of the engine - The most common external unbalanced moment is the 2nd order moment acting in vertical direction only and with a frequency corresponding to two cycles per engine revolution.
Read here

Guide Force H-Moments
The purpose of the cross heads of a two stroke slow speed diesel engine is to convert oscillation forces into rotation forces. The transverse reaction forces that occur when the engine crossheads are acting on the engine upper structure cause this guide force moment. Engines with 4-7 cylinders are having a guide force H-moment, which is identified as a transverse rocking movement of the engine top.
Read here

Guide Force X-moment
The purpose of the cross heads of a two stroke slow speed diesel engine is to convert oscillation forces into rotation forces. The transverse reaction forces that occur when the engine crossheads are acting on the engine upper structure causes this guide force moment. Engines with 7-14 cylinders are having a guide force X-moment, which is identified as a horizontal twisting movement of the engine top.
Read here

Hull Beam & Propeller Vibration
In cases where it is not possible to outbalance the source of a vibration, the second best choice is to outbalance the local vibration (symptom) where it occurs. The advantage of a lever arm between the inducing source and the compensator is utilized and consequently a relatively small imbalance is required to outbalance the local vibration.
Read here

How to calculate required compensator imbalance:

Main Dimensions

Download reference list here

Installation Examples

Compensator unit

Main engine RPM detection system

Synchronizing unit

Gertsen & Olufsen Vibration Compensators are world leaders in eliminating unwanted vibrations and improving the performance and comfort of ships and power plants.

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Name:	Susanne Knudsen
Initials:	SUK
Job title:	Shipping Secretary
E-mail:	suk@g-o.dk
Phone:	+45 45 164 167

Susanne Knudsen
Shipping Secretary
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The first systems were developed and commissioned back in 1989 and today more than 300 systems are in operation onboard ships and at power plants around the world. The compensator systems are produced, assembled and tested in Denmark.

Using a G&O vibration compensator as an alternative to traditional vibration damping

The majority of all harmful vibrations onboard a ship originate from either the propeller or the main engine, consequently our products are targeting these inducers. Traditional vibration damping tend to focus on the vibration itself (the symptom) and how to remove the local resonance – by using this method the symptom will be either reduced and/or transferred to other components, but the source will still be present.

The patented G&O systems, however, are having its focus on the source of a vibration problem – the vibration compensators are typically mounted directly on the main engines neutralizing the induced forces and moments and consequently no forces are transferred from the engine to the ships structures. When eliminating the source; the symptoms (vibrations) will automatically be eliminated.

Using a G&O vibration compensator as an alternative to traditional vibration damping gives the user many operational and economical advantages – Furthermore it opens new perspectives when designing vessel and corresponding main engines – engines types that in the past were considered troublesome can now be considered more or less moment free when using a compensator.