Ronda AG in Lausen (Switzerland) made their own inhouse entry-level movements from 1961 till the 80ies. The variety of movement was very big, ranging from simple pin lever movements to a microrotor automatic.
Among the latest movements of medium quality is the simple but true pallet lever movement Ronda 433, which bases on the pin lever caliber 1413. It was released in the 1970ies.
The Ronda 433 has got a diameter of 10 1/2 lignes and is equipped with 17 jewels.
The caliber 433, which bases on the base caliber Ronda 1413 is a movement in pillar construction, which is partially made like a Roskopf movement. More about that later.
After releasing the top plate, you'll be surprised not to find a pin lever, but a true swiss pallet lever.
The gear works are already modern made, with directly driven center second and missing minute wheel. The mainspring barrel drives the second wheel (at 1 o'clock) on the movement side.
A little odd is the position of the setting lever: It is located on the main plate (at 8 o'clock) and not, as usual, on the dial side.
How cost-efficient that movement was constructed can be seen on the balance statt: The ring balance with beats with contemporary 21600 A/h is located under a punched kind-of balance bridge, which is in fact only a balance cock, whose other end lies on the top main plate. And even more surprisingly, there are no ruby bearings for the balance, but two plastic(!) bearings.
To still achieve the number of 17 jewels, this movement has got lots of cap jewels. The three ones on top, which are attached on an own plate, have no real function, the movement works as good with, or without them.
The hands are driven on the dial side via the mainspring barrel.
The minute wheel is made of a cannon pinion with two gears at the one end.
The lower gear is driven by the outer gear of the mainspring barrel, the higher gear drives the exchange wheel. This is different to a Roskopf movement, where there's no exchange wheel, since both hands would be driven by gears on top of the mainspring barrel.
The Ronda 433 has got a rocking bar winding mechanism and a click mechanism on the dial side, which is pretty well made. The used rubies are also of better quality since they are domed and contain reservoirs for the oil.
In the lab
The specimen shown here came as completely gummed NOS movement into the lab and got a full service. After that, it still did not run. Further investigation showed, that the height adjustment of the balance cock was completely wrong and the balance wheel was stucked into the plastic bearings.
With a tiny distance ring and a screw, which was fixed by nail polish, the height adjustment could be fixed and the balance now beats with perfect amplitude, like on the its first day after production.
On the timegrapher, the movement shows rates, which are ok. Nevertheless, the maximum position difference of 50 secs per day is way too much for a pallet lever movement.
With better adjustment, the rates could more or less compenate them, so that there's no big deviation when worn.