Reduction gearbox 1:3.2 & 1:5

Jefa RG10-32 and RG10-50 reduction gearbox
The Jefa RG10 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 can be 1:3.2 (1.15 revolutions of the input shaft for a corresponding 72 degrees of rudder travel) or 1:5 (1.8 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. The output lever centres are 130 mm to a corresponding 200 mm centres 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 1:3.2 version is used for cruising/racing yachts with a big wheel (>1500 mm) fitted to achieve a direct and responsive steering (X43 and X46 example). The 1:5 version is used on yachts with smaller wheels (<1400 mm) when more revolutions are required.
The RG10 gearbox has 4 positions to integrate an optional 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 378 KgfM when the 1:3.2 input is used and 591 KgfM when the 1:5 input is used. This makes the gearbox suitable for boats from 30' to around 48'. 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 pictures for a larger view.
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Jefa transmission bevel reduction gearboxes

Part No.


Price in Euro


Reduction gearbox 1:3.2 including output lever



Reduction gearbox 1:5 including output lever



Shaft and bracket for autopilot for RG10 gearbox



Stop for RG10 gearbox


RG10 autopilot drive integration
The layout below shows a typical integration of a transmission autopilot drive unit on a type 1 & 2 RG10 reduction gearbox. The drive can be mounted on 4 positions: 2 at the input side and 2 at the output side.

RG10-32 and RG10-50 mounting example
The layout below shows a typical installation of a RG10 gearbox. The gearbox is placed near the rudder stock at an offset of 106 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).