Page 198 - Vetus

Power hydraulics

Power where you need it, for as long as you need it

The concept

VETUS Hydraulic Systems are an excellent way to move the power of a “Prime Mover” engine to user devices around the vessel, by
means of the controlled flow of high pressure fluid moving through flexible hoses or rigid tubes. The prime mover may be a main
propulsion engine, the engine of a diesel generator, or a “power pack” engine dedicated to powering the hydraulic system.
A user device is any item or system of mechanical equipment, including bow and stern thrusters, windlasses, capstans, winches,
cranes, hatch lifters, roll stabilizers and power steering.

The heart of the hydraulic system consists of one or more hydraulic pumps, each mounted on a simple gearbox called a Power Take
Off (PTO), itself mounted on an engine or propulsion gearbox. When a main propulsion engine is the prime mover of the hydraulic
system, mounting the PTO on the gearbox will usually provide the most convenient installation.

The hydraulic pump draws hydraulic fluid (a light oil) from a reservoir tank, and sends
that oil, at high pressure and flow, to valves that then control the flow of fluid to each
of the user devices.
VETUS hydraulic pumps are of the variable volume, load sensing type and provided that
the prime mover engine is developing enough power, these pumps can deliver maximum
flow and pressure at any engine speed. When no user device is operating, the pump
essentially freewheels, so no clutch is necessary. The temperature of the hydraulic fluid
must be maintained within certain limits and a seawater-cooled oil cooler is installed in
almost all systems.

Integrated hydraulic systems require advance planning so that engines or gearboxes are
ordered with appropriate PTOs and so that adequate space is reserved in the engine room
for the hydraulic reservoir tank. The installation of a hydraulic system requires extensive knowledge
of hydraulic theory and practice, with a larger skill set and more training and experience than is required
for the installation of electrical devices and equipment.

The cost of installing a single hydraulic user device such as a bow thruster will exceed the cost of installing a single electrically
powered device of similar output, but as more devices are added to the vessel and powered by the same central system of pumps,
oil coolers and reservoir, there will be a substantial reduction in the cost difference between the integrated hydraulic system and a
collection of electrical devices.

Compared to electrical systems:
• Hydraulic systems tend to get less expensive as more devices are installed whit-inn the same system (Pump, Tank, Cooler)
• Hydraulic systems tend to get lighter as more devices are installed to the single system
• Hydraulic systems are capable of generating more power compared to their size
• Hydraulic systems in general require less maintenance
- As far as single devices: An hydraulic thruster requires less maintenance than conventional thruster. But compared to the
RIMdrive and BOWpro, the maintenance level is the same
• Hydraulic systems in general are more reliable when looked after properly because most sensitive components stay with-inn the
warm, dry conditions of the engine room
• Hydraulic systems have the ability to operate continuously without run-time and overheating limitations compared to convention
electrical system
- The RIMdrive and BOWpro are examples of electrical systems that have no overheating limitations
Hydraulic windlasses

Hydraulic pumps

Hydraulic thrusters
Hydraulic thrusters
Hydraulic
stabilizers
Hydraulic tanks

198 Power hydraulics - Want to know more? Visit www.vetus.com