Transmission drive unit 200 Nm (12V)

Jefa 200 Nm transmission autopilot drive unit
The Jefa transmission drive is one of the most compact autopilot drives in the world. It's as strong as a human being (the max. output torque of 200 Nm is equivalent to 40 Kg on the rim of a 1 meter wheel) and is build for 24 hours per day continuous operation with a total weight of only 6 Kgs. The combination of the specially designed electric motor with the ultra efficient 3 stage 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 30 to 60 foot (or with a rudder torque up to 525 KgM) equipped with a Jefa transmission steering system and is available in three different speeds: 3.5, 6, and 8 revolutions per minute. The speed choice depends on the reduction of the steering system. See the compatibility table below. Please click on the pictures for a larger view.
Click for larger view Click for larger view
Main dimensions
The Jefa transmission drive is very compact with a length of 162 mm and a maximum diameter of 158 mm. As space is always a problem on sailing yachts, the compact drive unit can be integrated into the steering system even when a very limited space is available. The drive can be mounted on the BG11 and BG14 bevel gearboxes or directly on the RG10 reduction gearboxes. Please remind that a preparation for the autopilot integration is required when ordering the steering system. 
The mounting possibilities:

The transmission drive can be mounted on every (prepared) bevel gearbox in the steering system or directly on the RG type reduction boxes with multiple input shafts.
The construction:

The above assembly drawing shows a transmission drive mounted on a bevel gearbox. The drive can be separated in 3 main parts: The electric motor (1), the three stage planetary gearbox (2) and the electro-magnetic clutch (3). The Jefa transmission 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.
  • Aluminium motor housing in stead of sheet steel plate to avoid corrosion.

Planetary gearbox: To achieve a correct rudder travel speed (hard over time) the electric motor has to be reduced in speed with a factor 486:1. Some autopilot drive producers use a worm reduction box, but the efficiency is extremely low as the gears rub each other. Some producers use a combination of a planetary gearbox with a 2 stage spur gear set (one small gear and one big gear), but this creates a much bigger unit with an offset to the centre and much heavier loaded gears. The best way to achieve this high reduction in combination with a high torque is a 3 stage planetary gearbox. It's also the most expensive way as every gear step has 4 gears in stead of 2 gears but the huge advantages overrule the higher price:

  • 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 transmission 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:

  • Less friction to back drive the unit.
  • Lower power consumption (1.4 Amp. at 12 Volt, 0.7 Amp at 24 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 equalise the forces so the the clutch can disengage, making the manual take over much safer. 
200 Nm transmission drive DU-TS24-12 performance table: (in combination with the 1:7 reduction box RG10-70)
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
Connections:

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 0.75 mm² 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 steering system. The two 2 mm² 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. (not available in 24 volts)
Following table shows the maximum rudder torques at midships and full rudder that can be generated by the Jefa 200 Nm transmission drive in combination with various autopilot junction boxes and reduction gearboxes. As the transmission drive drives the steering system, the maximum rudder torque depends on the type of reduction box used in the system. The hard over time (HO-time) states the time it takes the drive to travel the full 72 degrees of rudder travel when the speed control of the pilot is set to maximum speed.
Autopilot junction box 12 Volt version. Max. output (Amp.) BRG10-50 & RG10-50 midships (KgM) BRG10-50 & RG10-50 full rudder (KgM) RG10-70 midships (KgM) RG10-70 full rudder (KgM) BRG10-67 midships (KgM) BRG10-67 full rudder (KgM)
DU-TS24-12 8 revs/min 11 sec. 16 sec. 15 sec.
DU-TS18-12 6 revs/min 14 sec. 21 sec. 20 sec.
DU-TS10-12 3.5 revs/min 24 sec. 36 sec. 34 sec.
Simrad AC12 12 123 233 172 327 165 313
Simrad AC20 20 169 321 237 449 226 430
Simrad AC40 40 fully functional, but smaller autopilot is advisable (money can be saved by choosing smaller autopilot)
B&G h1000 (*1) 25 169 321 237 449 226 430
B&G h2000 ACP-1 25 169 321 237 449 226 430
B&G h2000 ACP-2 40 fully functional, but smaller autopilot is advisable (money can be saved by choosing smaller autopilot)
Nexus-Silva A-1510 (*2) 15 158 299 220 419 211 401
NKE gyropilot 2 RVP (*3) 25 169 321 237 449 226 430
Navman G-Pilot (*4) 20 169 321 237 449 226 430
Northstar MCU600 (*4) 20 169 321 237 449 226 430
Furuno Navpilot 500/511/520 25 169 321 237 449 226 430
Raymarine X-10 (*5)(*6) 10 123 233 172 327 165 313
Raymarine X-30 30 169 321 237 449 226 430
(*1) Please use part number h1000-CUW specially made for Jefa drives, equipped with dynamic braking. Don't use the standard h1000.
(*2) 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.
(*6) 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.
Pricing

Jefa transmission drive units

Part No.

Description

Price in Euro

DU-TS24-12

Transmission autopilot drive unit 200 Nm 12 Volts - 8 rev/min *¹

 € 1.600

DU-TS18-12

Transmission autopilot drive unit 200 Nm 12 Volts - 6 rev/min

 € 1.600

DU-TS10-12

Transmission autopilot drive unit 200 Nm 12 Volts - 3.5 rev/min

 € 1.600
(*1) Standard version. use this one when not further specified.
Service information:
Please click the left picture to open the Jefa 200 Nm transmission drive explosion drawing and parts lists.