Details at a glance:

• High torsional stiffness due to 60mm side plate spacing
• Main rotor shaft 12 or 15mm
• Different dome bearing heights available
• Axial bearing for main rotor shaft standard
• Disc and bevel gear ratio made of high-quality steel
• Main rotor direction of rotation left- or right-rotating
• High flexibility in selecting the main rotor speed depending on the gear ratio
• Tail rotor drive directly or via special tail gear ratio
• High flexibility when selecting the tail rotor speed depending on the rear gear ratio
• Servo arrangement directly under the swash plate for direct linkage
• No centrifugal clutch
• Adjustable tension pulley for toothed belts in the 1st gear stage
• Simple turbine integration due to robust claw coupling
• Exhaust pipe selectable as Twin Exhaust or Single Exhaust (only for L version)
• Tail boom bracket optionally available
• FENESTRON actuator available, e.g. for EC145 T2
• Electronic control by optimized JetCat ECU software
• No throttle curve (Throttle Curve) necessary

The new robust 2-shaft helicopter mechanics SPT-HMS ("S" = short) and SPT-HML ("L"= long) were specially developed for model helicopters with a high take-off weight.

The side plates, struts and bearing blocks are made of aluminium, the side plate spacing is 60mm and gives the mechanics a high torsional stiffness. The arrangement of the 2-shaft turbine in the SPT-HML is shifted forward by 85mm, this arrangement is characterised by an improved centre of gravity position, e.g. in industrial helicopter applications. On so-called industrial helicopters, the tail boom is usually realised with an aluminium or CFRP tube, and can be attached to the mechanics using an optionally available tail boom bracket. The high-quality, ground gear ratios guarantee reliable power transmission to the main and tail rotor. The 2-shaft turbine (SPT5-H or SPT10-RX) is integrated into the mechanics via a large claw coupling. The drive power is then transmitted via a solid toothed belt stage to the ring gear, which is made of special steel. The input and output bevel gears have been adapted according to the latest findings. The autorotation freewheel is integrated in the output belt wheel. The tail rotor is either driven directly by the ring gear (rotating tail rotor during AR landing) or via a special tail transmission (tail rotor standstill during AR landing). The special tail gear ratio is directly driven by the turbine, in this configuration optimum tail rotor speeds can be achieved.

For the use of FENESTRON tail rotors, e.g. EC 145 T2, an adapted gear ratio can be installed. The main rotor speed can also be optimally adjusted. This allows main rotors from 2.0m to 2.6m to be driven powerfully. The direction of rotation of the main rotor can of course be freely selected. A centrifugal clutch has been dispensed with, as there is no mechanical connection between the core turbine and the power turbine in 2-shaft turbines.

Model helicopters with a large take-off weight load the main rotor shaft with a high "mast torque". Therefore you can choose between a 12mm or 15mm main rotor shaft depending on the model helicopter weight. Furthermore, the "mast torque" can be positively influenced with various available dome extensions.

The system speed of the helicopter should always be kept constant during flight, a throttle curve is not necessary with the JetCat-ECU control. A Hall sensor measures the transmission output speed. The respective transmission ratios are freely programmable in the ECU (gear output to main rotor, main rotor to tail rotor). The user can program the desired main rotor speed directly, the rest is done by the ECU software.