Principle of operation
When a direct connection between the rudder shaft and the column is not possible by means of an “RP” transmission system, the most direct, reliable and robust steering system, in this case is the Jefa transmission system.
This system can be installed from series 100, 200, 300 and 400 columns. It is based on the same principle as the rack and pinion system; the rotational movement of the wheel is transformed into an alternating linear movement through gearboxes, drive shafts and cardan joints. In this way, the distance between the steering wheel and the rudder shaft can be very large and the path very complex.
The advantages of this system compared to traditional brake systems are considerable:
– Reduction of the efforts transmitted by the system to the structure of the boat.
– Variable gearing: thanks to the two arms of different lengths, the system progressively becomes more and more geared as the rudder angle increases.
– Possibility of installing the autopilot actuator directly above or below the reduction box.
The BG12 and BG15 transmission boxes are intended to be mounted from inside the column or bulkhead.
The reduction ratios are 1:1 for BG12 and 1,2:1 for BG15 respectively. Both models are complete with disc brakes.
When mounting is to be carried out completely from the outside, the BG12QM or BG15QM are used.
The Jefa BG10 and BG13 gearboxes are made of black anodized 6082 aluminium and are used when the path of the reduction system requires a 90° angle.
The shafts are made of special stainless steel and rotate on sealed bearings. The mounting flange can be positioned as desired without disassembling the input shaft. The reduction ratios are 1:1 for BG10 and 1,2:1 for BG13 respectively.
A further 4 models of return boxes are available:
– BG11 and BG14, 3-way models, ratios as for BG10 and BG13.
– BG11AP and BG14AP, 3-way models with flange for Jefa pilot actuator (see page 13)
The reduction boxes transform the rotation movement into an alternating linear movement and are made of black anodized 6082 aluminium. The shafts are made of special stainless steel and rotate on sealed bearings.
There are two types of reduction boxes available:
The BRG10-50 and 67 are reduction and bevel gear boxes, while the RG10-32,50,70,100 are reduction only boxes.
Universal couplings, drive shafts, bulkhead bearings
The universal joints of the 10 series are made from solid 6086 aluminium. The 7075 aluminium cruise is strong and light.
The TT10 drive shafts are extruded from silver anodized 6082 aluminium. Outer diameter 45 mm. The UJ11 joint is a special version of the UJ10 joint. It is used in conjunction with the FB10 bearing for installation through a bulkhead.