|
compact
autopilot drive unit |
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| Jefa 100 KgM autopilot compact drive unit |
The Jefa compact drive is a strong and compact integrated autopilot drive
and much more efficient than existing hydraulic and electro-mechanical
linear
autopilot drive units (for the why and how, please see our
Q&A page). With a max. rudder
torque torque of
100 KgM (equivalent to 100 Kg force on the end of a 1 meter steering
tiller) it's build for 24 hours per day continuous operation with a
total weight of only 9,7 Kgs. The combination of the flat wound (pancake) electric motor with the ultra efficient
planetary gearbox results in an extremely efficient drive unit to keep
the battery charging time to the minimum. The drive can be used on boats
from 20 to 45 foot l.o.a. (or up to 100 Kgm rudder torque) equipped with a
Jefa mechanical rack and pinion steering system.
Please click on the picture for a
larger view. |
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The Jefa compact drive unit is designed to be integrated with the Jefa
RP100, RP150, RP200, RP300 & RP400 rack and pinion pedestal. It's
mounted just underneath the cockpit floor saving the room in the back of
the boat normally occupied by an autopilot drive unit. The compact drive
is very easy to mount. The original stopring is removed and the pedestal
mounting bolts are used for mounting the drive unit. Please have a look
at the below video which shows how the compact drive is mounted. |
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Deck thickness limitations: |
|
This illustration shows the limits of 20 to 32 mm of the deck thickness.
Outside these limits the compact drive is not usable without custom work
on the pedestal. |
The above animation shows the setup of the compact drive. The drive can be separated in
4 main parts: The electric motor, the planetary gearbox,
the
electro-magnetic clutch and the final spur reduction gearbox. The Jefa
compact drive has multiple
advantages over existing integrated drive units. These advantages will
be explained per section of the drive:
Electric Motor: The flat wound electric motor
(pancake motor) used in the Jefa
drive units is carefully selected for this application. Pancake motors
have multiple advantages over normal electric DC motors:
- A large flat wound rotor to achieve a high starting toque and an
immediate response to the autopilot speed control signal.
- A motor efficiency of 72,5% to achieve a minimal power consumption
and maximal mechanical power output (compared to max. 50% efficiency
of a normal DC motor).
- Compact main dimensions compared to achievable output.
Planetary
gearbox: To achieve a correct rudder travel speed (hard over time)
the electric motor has to be highly reduced in speed. Some
autopilot drive producers use a worm reduction box, but the efficiency
is extremely low as the gears rub each other. The Jefa compact drive uses a
planetary gearbox which has following
advantages:
- The highest possible efficiency compared to any other gearbox.
- All forces are equally spread over 3 gear teeth in stead of one
allowing a much compacter and stronger solution.
- The forces and torques from the motor to the output shaft remain
in the centre line of the drive unit, resulting in a higher
efficiency and extremely reduces the loads on the housing and other
internal parts.
Electro magnetic clutch: On the moment the mechanical steering system on the yacht is manually operated, the autopilot drive
has to be disconnected from the steering system. This is achieved with
the electro-magnetic clutch and controlled automatically by the
autopilot junction box. Jefa has developed a unique engagement clutch. The solution is based on
a electrically operated
spring loaded clutch pin that engage and disengage the outer gear ring
of the planetary gear step. This solution has multiple advantages over
the existing friction plate clutches:
- Less friction to back drive the unit.
- Lower power consumption (1.4 Amp. at 12 Volt).
When the clutch isn't powered, it's disengaged and engaged when
powered.
- The clutch doesn't wear in time.
- More compact than any friction clutch.
- When the autopilot is switched off, the helmsman isn't suddenly confronted
with the full rudder torque, but has to put loading on the wheel to
equalize the forces so the the clutch can disengage, making the
manual take over much safer.
|
This illustration shows the minimal components for a working autopilot
configuration. Jefa autopilot drives work together with all mayor
autopilot electronics. The connection of the Jefa autopilot drive to the
autopilot junction box is quite simple. The two 1.5 mm˛ red and black
wires have to be connected to the plus and minus of the autopilot clutch
line. This will make sure that when the autopilot user engages the
autopilot on the control screen, the clutch will engage and allow the
autopilot motor to drive the rudder. The two 2 mm˛ red and
black wires have to be connected to the autopilot drive output
connection. Now the Jefa autopilot drive is integrated into the system. |
| Compatibility in 12 Volts. |
|
Following table shows the maximum rudder torques that can be generated
by the Jefa compact drive in combination with various autopilot junction
boxes. |
| Autopilot junction box
12 Volt version. |
Max. output
(Amp.) |
Rudder
torque (KgM) |
|
Garmin GHP12/GHC10 sailboat APS (*1) |
40 |
100 |
|
Simrad AC12 |
12 |
100 |
|
Simrad AC40 |
40 |
100 |
|
Raymarine X-10 (*2) |
10 |
100 |
|
Raymarine X-30 |
30 |
100 |
|
Nexus-Silva A-1510 (*3) |
15 |
100 |
|
NKE gyropilot 2 RVP (*4) |
25 |
100 |
|
Navman G-Pilot (*5) |
20 |
100 |
|
Northstar MCU600 (*5) |
20 |
100 |
|
Furuno Navpilot 500/511/520 |
25 |
100 |
| (*1) A special Garmin version of the
compact drive is available under code number DU-CD-12/GA.
The Garmin rudder feedback unit is integrated and special Garmin
connectors are wired to the drive unit. |
| (*2) We strongly advise to not use the
standard X10 autopilot as it delivered without rudder feedback unit.
Without rudder feedback unit the autopilot is not aware of actual rudder
angle. In very slow speed conditions or in conditions of a stalling
rudder blade, the autopilot doesn't stop with powering the drive unit,
running it against the rudder stops and still continuing to power the
drive. In time the drive fuse will blow, but mechanical damage can occur
in the drive unit which will not be covered under our warranty terms as
we can identify this specific damage. We strongly advise only to use the
X10 unit in combination with the optional rudder feedback unit or use
the X30 unit. Please read the special installation instructions for the
clutch available on our FTP server via
this direct link. |
| (*3) Please read the special installation
instructions for the clutch available on our FTP server via
this direct link. |
| (*4) Please read the special installation
instructions for the clutch available on our FTP server via
this direct link. |
| (*5) Please read the special installation
instructions for the clutch available on our FTP server via
this direct link. |
Jefa
compact drive unit |
Part
No. |
Description |
Price
in Euro |
DU-CD-12
|
Compact autopilot drive unit 12v for RP100-400 |
€ 1.880 |
DU-CD-RFB |
integrated rudder feedback unit for compact drive (*6) |
€ 203 |
DU-RE-12 |
contactor (relais) for clutch 12 volts. (see above *2 to *5) |
€ 17 |
| *6: Only possible for Jefa, Garmin, Nexus and NKE
autopilots (all 10 kΩ). |
 |
Please click the left picture to open the compact drive explosion drawing
with parts list. |
