Reduction gearbox 1:7

Jefa RG10-70 reduction gearbox
Click for larger view The Jefa RG10-70 reduction gearbox transforms a rotational movement into a push-pull movement. The reduction gearbox is always positioned close to the rudder stock. Via a draglink with rose joints, the push-pull movement is transmitted to the tiller lever and rudder shaft. The RG10 gearbox is very versatile as it can be equipped with one (standard), two or three input shafts. On top of that one can choose the output shaft at the opposite side of the input shafts (type 1) or at the same side (type 2). The gear ratio IS 1:7 (2.5 revolutions of the input shaft for a corresponding 72 degrees of rudder travel). This can be increased with steps of 1.2:1 by using step ratio bevel boxes (3.1 turns with one step ratio and 3.8 turns with two step ratio bevel boxes). The output lever centres are 165 mm to a corresponding 250 mm centres of the tiller lever or 200 mm to a corresponding 307 mm of the tiller lever. This difference in length results in the so called "wide angle geometry". Please click here for more in depth explanation.
The RG10-70 gearbox has 6 positions to integrate an optional Jefa transmission autopilot drive unit. Integrating an autopilot drive in a steering system has never been so easy.
The maximum input torque is 40.5 KgfM resulting in a maximum rudder torque at full rudder of 828 KgfM. The maximum rudder torque according to the CE rating is 291 KgfM midships and 552 KgfM full rudder (the CE regulations use a safety factor of 150%). This makes the gearbox suitable for boats from 45' to around 65'. Except for the input shafts and the gears, the complete gearbox is machined out of solid aluminium 6082 for maximum strength and minimum weight. Positioning the reduction gearbox correctly to the rudderstock is very important for the wide angle geometry to function correctly. Please look at the mounting examples at the bottom of this page. Please click on the picture for a larger view.

Jefa transmission bevel reduction gearboxes

Part No.


Price in Euro


Reduction gearbox 1:7 including output lever



Shaft and bracket for autopilot for RG10 gearbox


RG10-70 autopilot drive integration
The layout below shows a typical integration of a transmission autopilot drive unit on a type 1 RG10-70 reduction gearbox. The drive can be mounted on 6 positions: 3 at the input side and 3 at the output side.

RG10-70 mounting example
The layout below shows a typical installation of a RG10-70 gearbox. The gearbox is placed near the rudder stock at an offset of 127 mm or 162 mm. This offset is necessary to achieve a correct wide angle geometry (click here for more information). A good confirmation of the correct geometry is to check if all 4 endpoints of the lever pins are in one line (see the green line in the layout).

RG10-70 operating centres in mm valid for 72 (2x36) rudder travel.

Output centre distance Offset distance Tiller centre distance
130 (short lever) N/A N/A
165 (standard long lever) 127 250
200 (extra long lever) 162 307