Ronda 4135

 
Ronda 4135

Ronda 4135

Description

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 34 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.

Video on YouTube

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

gears and trains

gears and trains

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 jewel

detail: 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 plate

main 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 barrel

empty 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 mechanism

date 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 clutch

driving wheel and clutch

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

Ronda 4135 dial side

Ronda 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.

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.

Timegrapher result

On the timegrapher, this unadjusted movement performed well, especially, when you take into account, that it was stored for many years before.
crown right (12 up)

crown right (12 up)

crown up (3 up)

crown up (3 up)

crown left (6 up)

crown left (6 up)

crown down (9 up)

crown down (9 up)

dial up

dial up

dial down

dial down


horizontal positions
dial up+24 s/d
dial down+10 s/d
vertical positions
crown right (12 up)-15 s/d
crown up (3 up)-15 s/d
crown left (6 up)-30 s/d
crown down (9 up)+-0 s/d
Timegrapher output

Technical data

Manufacturer:Ronda
Caliber:4135
Number of jewels:17
Escapement:Pallet lever
Balance types: Nickel anular balance
Shock protection(s): KIF Protechoc
Balance bearing / direction hairspring:Counterclockwise
Moveable stud:yes
Adjust mechanism:Hairspring key
Construction:
  • lever
  • escape wheel, seconds wheel, third wheel, large driving wheel
  • mainspring barrel
Construction type:solid construction
Winding mechanism:yoke winding system
Setting lever spring:4 hole(s)
Features:SCD,QG,RDR
Functions:hour, minute, second, day
A/h:21600
Size:8 3/4''' (measured: 19,1mm)

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