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The new mount launched on the market by Officina Meccanica Bellincioni is named Beta P (“Beta” is the model and
P stands for “Pesante”, heavy in Italian) and it has several unique and innovative characteristics.
The first important characteristic of the P mount, that no other mounts on the market have, is that the polar
axis tube can rotate through 90°. This characteristic gives two main advantages; the first one is that it can be used from the equator to the poles with a simple adjustment of the rotation system and
with no need to dismantle or perform any potentially difficult movements, the second advantage is that the Equatorial mount can also be used as an Altazimuth mount, providing 2 instruments in 1 and
therefore being very marketable.
Moreover, the P mount is available in both the traditional German set up and the fork set up, providing 4 different configurations, as shown
below:
Beta P mount possible configurations :
German Equatorial - German Altazimuth
Fork Equatorial - Fork Altazimuth
The 90° rotation movement has been achieved with an especially designed reduction system made of a screw worm
and gears. The whole mount structure has then been fixed onto two 30 mm thick hinges with a 180mm diameter, undoubtedly over-specified for the load declared. Thanks to a clamp system it is possible to
loosen the hinges and adjust the polar axis and then tighten them up again. In this way the whole system acts as a unique box releasing the forces on a wide base made of two arms in solid aluminium 30mm
thick. Bench tests have also proved how effective this system is in preventing vibrations which could disturb the observation session being transmitted to the body of the mount and reach the telescope.
The Fork set up is made of two 25mm thick arms with a C shaped section. One arm is provided with a screw worm
reduction system used to drive the telescope, the other one is provided with a double crown ball bearing having a slight axial play to compensate possible expansion and a bar with counterweights to
balance the weight differences between the two arms to avoid any strain on the structure.
The distance between the two saddle support plates of the fork is a generous 547.5 mm which gives the opportunity of mounting a wide range
of telescopes with their photographic instruments.
Talking about stability, another element which gives extra-strength to the P mount is the rotation group for the right ascension and
declination which moves on SKF bearings (normally used for extreme applications). According to what SKF declares, the life of a 33013 bearing (like those used on the P mount) is 2 million cycles with
loads of around one tonne. The use of over-specified bearings for an application which wouldn’t normally need them will guarantee against endless structural flexions due to the telescope load.
The other elements of the mount are just as robust. The tube and the bell housings are made at the machine tool from solid aluminium, the
rotation shafts are turned on a lathe from high quality thick stainless steel bars which guarantee high loads and resistance to corrosion.
Last but not least, we ought to mention the sensitive transmission system consisting of a bronze toothed wheel
and a ground stainless steel screw worm used for the right ascension and declination movements. This system was designed, manufactured and carefully checked by Franco Bellincioni to limit the periodic
error as much as possible. For this purpose, the Bellincioni workshop owns a testing bench with high precision optical ruler to check the movements of all the models in production.
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