Vetus EHPA12R2 Instructions D'installation page 9

Introduction
The installation of an electrohydraulic pump (EHP), integrated
into an hydraulic steering system, makes it possible to steer a
boat via automatic steering gear (autopilot) or selector switch
(gear lever 'joy stick' or a manual remote control unit) options.
The capacity of a suitable EHP should match the stroke volume
of the respective cylinder (displaced oil volume for board-
to-board rudder deflection) and the required board-to-board
steering time.
Calculation of an EHP
Determine the volume of a cylinder that has been or is to be
installed. For details please see the technical specifications
published by the supplier of the control unit.
Divide the cylinder capacity by the required board-to-board time
to determine the capacity of the suitable EHP .
Example:
The board-to-board time of a given boat is 15 seconds.
The selected cylinder is a Vetus MTC72 model. This cylinder
has a volume of 146 cm3.
Capacity calculation:
3
Cylinder volume in cm
Board-to-board time in seconds
3
146 cm
3
x 60 = 584 cm /min (35.6 cu.inch/min)
15
Thus, the required EHP must exhibit a capacity of approximately
584 cm 3 /min (35.6 cu.inch/min).
A suitable EHP type for this purpose is the Vetus EHP type
'EHPB R2' with a capacity of 700 cm
The board-to-board time is 12.5 seconds.
Operation EHP with a reversible motor (EHPA R2,
EHPB R2, EHPC R2)
The EHP consists of an oil pump (driven by a reversible elec-
tromotor), relief valves, suction valves, a check valve, a by-pass
valve and a tank.
Depending on the rotation direction of the electromotor, the oil
is pumped from one side of the piston to the other side of the
piston - and vice versa.
vetus® Electro-Hydraulic Pumps
3
x 60 in cm /min
3 /min (42.7 cu.inch/min).
General
There are two types of cylinders; i. e., 'balanced' or 'symmetri-
cal' cylinders (with a continuous piston rod) and 'unbalanced'
cylinders (with a non-continuous piston rod ).
The Vetus EHPs may be connected to balanced as well as
unbalanced cylinders, due to the fact that the EHPs possess
a bypass. Thus, the oil volume which enters the oil pump from
one side of the cylinder does not need to equal the volume
which leaves the oil pump in the other direction.
Besides, the Vetus EHPs also lend themselves to use with a
cylinder set (2 cylinders with a non-continuous piston rod, a
double rudder, or two single rudders).
The following recommendations should be observed to
prolong the lifetime and improve the performance of your
electrohydraulic pump (EHP).
- Only use hydraulic oil in accordance with the technical
specifications
- Make sure the battery voltage is correct
- Limit the voltage loss over the battery cables by using
cables with an adequate diameter
- Ensure regular maintenance
ENGLISH
7
020203.06