direct drive unit type DD3 |
Jefa 5040 Nm (525 KgM) autopilot direct drive unit type DD3 |
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Some mounting possibilities: |
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The left illustration shows the direct drive combined on the steering tiller lever. A long output lever is fitted to achieve the correct geometry. The right illustration shows a direct drive mounted on a separate lever independently from the steering system. |
The three possible operation centres: |
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Direct drive operating centres in mm valid for 72° (2x36°) rudder travel. |
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Output centre distance | Offset distance | Tiller centre distance |
130 | 106 | 200 |
165 | 127 | 250 |
200 | 162 | 307 |
The choice of multiple tiller centres is a great advantage over other drive units. Depending on the application, the appropriate centres can be chosen. When the direct drive operates on an independent lever, the small tiller centres are chosen. When the direct drive is combined with the steering on one lever, the 250 mm tiller centres are chosen. The 307 tiller centres are only chosen when there is no possibility to use the smaller tiller centres. |
The construction |
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The above assembly drawing shows a cross section of the direct drive. The drive can be separated in
4 main parts: The electric motor
(1), the three stage planetary gearbox (2) and the
electro-magnetic clutch (3) and the 1:5 spur reduction gearbox (4). The Jefa
direct 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 used in the Jefa drive units is not a standard industrial motor, but specially designed and produced for this application. This solution is more expensive but there are multiple advantages over standard industrial motors.
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 (4) and controlled automatically by the autopilot junction box. Jefa has developed a unique and patented engagement clutch. The solution is based on two electrically operated spring loaded clutch pins that engage and disengage the outer gear ring of last planetary gear step. This solution has multiple advantages over the existing friction plate clutches:
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DD3-12 volts performance table: |
rudder torque full rudder (KgM) |
rudder torque midships (KgM) |
power usage (amps) |
rudder rotation per second (degrees/sec.) |
time for 72° rudder (sec) |
0 (no load) | 0 | 0.2 | 4.5 | 16 |
145 | 73 | 5 | 3.8 | 19 |
218 | 109 | 7.5 | 3.4 | 21 |
364 | 182 | 13 | 2.5 | 29 |
436 | 218 | 15 | 2.3 | 32 |
582 | 291 | 21 | 1.3 | 55 |
DD3-24 volts performance table: |
rudder torque full rudder (KgM) |
rudder torque midships (KgM) |
power usage (amps) |
rudder rotation per second (degrees/sec.) |
time for 72° rudder (sec) |
0 | 0 | 0.1 | 3.7 | 19 |
145 | 73 | 2 | 3.6 | 20 |
364 | 182 | 5 | 3.2 | 23 |
582 | 291 | 8.5 | 2.9 | 25 |
Connections: |
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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 4 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 at midships and full rudder that can be generated by the Jefa DD3 direct drive in combination with various autopilot junction boxes. |
Autopilot junction box 12 Volt version. | Max. output (Amp.) | Rudder torque midships (KgM) | Rudder torque full rudder (KgM) |
Garmin GHP12 sailboat APS (*1) | 40 | 263 | 525 |
Simrad AC12 | too small, don't use in combination with this drive | ||
Simrad AC42 | 30 | 263 | 525 |
Raymarine ACU-200 (*2) | too small, don't use in combination with this drive | ||
Raymarine ACU-400 (*2) | 30 | 263 | 525 |
NKE gyropilot 2 RVP (*3) | 25 | 263 | 525 |
Furuno Navpilot | not advisable due to lack in speed control and dynamic braking see this page | ||
B&G H5000 Pilot (*4) | 30 | 263 | 525 |
B&G Triton Pilot - High Current | same as Simrad AC42 - see above |
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Compatibility in 24 Volts. |
Following table shows the maximum rudder torques at midships and full rudder that can be generated by the Jefa DD3 direct drive in combination with various autopilot junction boxes. |
Autopilot junction box 24 Volt version. | Max. output (Amp.) | Rudder torque midships (KgM) | Rudder torque full rudder (KgM) |
Garmin GHP12 sailboat APS (*1) | 40 | 263 | 525 |
Simrad AC12 | 12 | 263 | 525 |
Simrad AC42 | 30 | 263 | 525 |
Raymarine ACU-200 (*2) | 15 | 263 | 525 |
Raymarine ACU-400 (*2) | 30 | 263 | 525 |
Furuno Navpilot | not advisable due to lack in speed control and dynamic braking see this page | ||
B&G H5000 Pilot (*3) | 30 | 263 | 525 |
B&G Triton Pilot - Low Current | same as Simrad AC12 - see above | ||
B&G Triton Pilot - High Current | same as Simrad AC42 - see above |
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Jefa direct drive units type 3 |
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Part No. |
Description |
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DU-DD3-12 |
Direct drive 525 KgM type 3 12 Volts |
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DU-DD3-12/GA |
Direct drive 525 KgM type 3 12 Volts, incl. Garmin rudder feedback and cables |
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DU-DD3-24 |
Direct drive 525 KgM type 3 24 Volts |
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DU-DD3-24/GA |
Direct drive 525 KgM type 3 24 Volts, incl. Garmin rudder feedback and cables |
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DU-TS-RFB1 |
TS integrated rudder feedback for Garmin and NKE autopilots (10 kΩ) |
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DU-TS-RFB2 |
TS integrated rudder feedback for Raymarine autopilots (5 kΩ) |
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DU-TS-RFB3 |
TS integrated rudder feedback for Raymarine autopilots (5 kΩ) |
The direct drive comes standard with the long output lever and should be completed with a draglink, a tiller pin and in some cases a tillerarm. |
Service information: |
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Please click the left picture to open the DD3 folder on our ftp server for the explosion drawings and parts lists. |