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Ronda 4135

Ronda 4135Ronda 4135


In the late 70ies, the swiss Ronda AG launched their caliber line 4x3y, to which belonged the Ronda 4135 shown here. It's a manual wind movement of the smallest diameter (8 3/4 lignes) of this series. All the other movements of this family, upto the 12 ligne selfwindig movement 4439R base on that movement and mostly differ by the size of the main plate and by additional features.

The Ronda 4135 is an econimically built, true pallet lever movement.

gears and trainsgears and trainsside view of the gearsside view of the gears

It's a contemporarily modern construction with directly driven center second and an indirectly driven cannon pinion on the dial side. The beating frequency is 21600 A/h and its nickel ring balance is beared in two KIF Protechoc bearings.

detail: pressed cap jeweldetail: pressed cap jewel

You can see the efficient construction of this movement on the way, the bearing and cap jewels, 17 of them, are installed: In the plates, there are quadrangular(!) recesses, which the jewels are pressed into. In which way this method is superior than using traditional round holes for pressing in the jewels, is unknown to me.

main platemain plate

Unlike most other Ronda movements, which a watch maker sees on his deck, this one is a "RAX" marked movement, which means, that it uses a swiss pallet lever. Nevertheless, some attributes of a Roskopf movement can still be found here, especially the driving of the cannon pinion by the mainspring barrel.

 empty dial side with open mainspring barrelempty dial side with open mainspring barrel

On the dial side, you can also see the economical construction: The mainspring barrel is completely open to that side, and the setting lever angle is just a rather large punched sheet. At "12:00", there's the bearing of the intermediate wheel for the date quickset mechanism, and at "11:30" the long bearing, in which the quickset wheel either advances the date ring, or disconnects it when turned the other way round.

date indication mechanismdate indication mechanism

The date mechanism is very interesting: By turning back the time, the correction wheel engages at "11:30" with the date ring and pushes it forward. By advancing the time it slips through, and discouples the mechanism.

driving wheel and clutchdriving wheel and clutchinside of the clutchinside of the clutch

To avoid damaging the quickset mechanism, the clutch is moveable and doges when it is turned backward.

Ronda 4135 dial sideRonda 4135 dial side

The date indication mechanism is clearly the highlight of this movement since it is really unusual and rare, but it is very efficient and due to the U-spring, it's a challenge for a watchmaker.


 Technical data

Number of jewels17
EscapementAnchor with pallets
Shock protection(s)KIF Protechoc
Balance cock directioncounterclockwise
Hairspring studmoveable
Regulator typeHairspring key
Movement constructionFork
Escapement wheel, Fourth wheel, Third wheel, Large driving wheel
Mainspring barrel
Construction typesolid construction
Winding mechanismyoke
Setting lever spring4 holes
FunctionsHour, minute, second, day
Beats per hour21600
Size83/4''' (measured: 19,1 mm)
Ronda 4135RondaRonda41358 3/4'''Ronda 413517 Jewels, 8 3/4''', 21600 A/h, SCD,QG,RDR


In the lab

The specimen shown here is a NOS movement, which was probably stored for twenty years, before it got into the lab. It was not serviced at all.

On the timegrapher

On the timegrapher, this unadjusted movement performed well, especially, when you take into account, that it was stored for many years before.

crown rightcrown right crown topcrown top crown leftcrown left crown bottomcrown bottom 
dial topdial top dial bottomdial bottom 

vertical positions
12 up  -15 seconds/day
3 up  -15 seconds/day
6 up  -30 seconds/day
9 up  +-0 seconds/day
horizontal positions
dial down  +10 seconds/day
dial up  +24 seconds/day
timegrapher measurings

The difference between the vertical and horizontal positions could be the effect of a light gumming of the movement.

Nevertheless, for a rather low end pallet lever movement, the results are absolutely OK, and maybe, if the movement ran for some weeks or a full service were made, it had performed even better.



Thank you very much to the Ermano Uhrwerke Gmbh for the donation of this movement and further technical papers.