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Balcony View

Power Packs

2 x AC WR45.jpg

A selection of the Wills Ridley Power Packs are shown in the  above/below. The Power Pack is the Hydraulic power unit (HPU) used in any powered steering system as the prime mover for the system. It delivers oil to the system without the need for human effort.

These units consist of the hydraulic pump and the related output control valves.

Each pump is driven by either an electric motor or an engine driven input.


Electrically driven

The vessel's available electrical supply will determine what motor can be fitted.

Wills Ridley can provide Power Packs for all electrical supply types. Including 3 phase(50 or 60Hz), single phase or DC (12 or 24v). This supply must be stated by the purchaser when ordering.

The Power Pack selection will depend on the type of steering controls required and the hydraulic circuits necessary to provide delivery of the control to the steering actuators.

Systems requiring classification society approval form the major part of our sales of Hydraulic Power Packs.

Many systems include two separate Power Packs or one Power Pack with two motors.

These motors can be run from different supplies.

E.g One - 3 phase for main steering and One - 24vdc for emergency backup.


Engine driven

Drive of the pump unit is taken from the engine.

This can be a direct drive from one of the PTO(power take off) outputs of the engine, or indirectly via a pulley and belt drive mechanism fitted to an engine output shaft. In both cases the details of the output drive must be stated by the purchaser when ordering.


An Engine Driven Power Pack with a Pressure Compensated Pump has been designed to increase efficiency and reduce heat in the steering gear. With a standard gear pump connected to the PTO, the oil flow fluctuates based on the engine RPM and constantly circulates oil whether there is a demand or not. With the pressure compensated pump, the swash plate of the pump will back off and will only circulate a minimal amount of oil until there is a demand. 

Generally for both electrical and engine driven power packs,

The size of the oil tank and motor power will depend on the amount of oil and pressure required to be delivered to the steering system. On some systems with two motors on one tank, the oil tank is divided inside by a weir plate. The weir plate keeps oil separately available for each pump set.

Oil cooling is achieved through correct sizing of the power pack oil reservoir for the service power and conditions to which it is being fitted.

Water or air cooled systems are generally not used in Wills Ridley systems. They are more commonly used in systems with small oil tanks or high load and pressure requirements.

Water/air cooled systems can be inefficient as the cooling capacity will depend on the difference in the oil temperature to water/air temperature.


The PQ range of power packs

This range of Power Packs are generally used for small systems or for auto pilot control.

This range includes both constant running DC motor units and reversing motor units.

The constant running units use solenoid coil (12 or 24vdc) to direct the output flow.

The reversing motor unit uses the polarity change to reverse the motor running direction. This reverses the output flow.

The type of unit used must be selected to match the auto pilot or small system to which it is to be applied.

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