Amida 4350

Description

In the mid 1970s, Amida released their caliber family 420 with pin lever movements in a Roskopf-like construction, to which the Amida 4350, a 10 1/2 x 11 1/2 ligne windup movement with direct read indication, belongs. This movement was e.g. used in the legendary Amida Digitrend, which should be a low-cost alternative to the popular LED (LCD was still too expensive) watches at that time and even achieved cult status.

On the base plate of this pillar movement, you will immediatly recognize the lack of bearing rubis. Additionally, you should not be fooled by the hallmark “Amida 420”, since this is the base caliber number, engraved in all base plates of this caliber family.

Contemporaneous to the caliber family Amida 420, there was the caliber family Amida 710, which used the same Roskopf-like construction, but had a pallet lever escapement, bearing jewels for all pivots and a better executed ratchet. In this caliber series, there was a direct read version, too.

The gear train is a Roskopf construction. It does not have a movement side minute wheel, but four reductions wheels following the mainspring barrel: Second wheel, third wheel, decentral seconds wheel and escape wheel.

The shape of the escape wheel is noteable, since it reminds strongly of this of a pallet lever movement.

The Amida 4350 has got a simple two leg anular balance, which is beared in two KIF Protechoc shock protection bearings with steel bearings and caps.

The beating rate of this pin lever movement is 18000 A/h. It can be adjusted at the hairspring key only.

On the dial side, there are multiple oddities:

First, Roskopf-like, the hands are driven on the dial side only, but in contrast to a true Roskopf movement, no slipping clutch on the mainspring barrel is used, but a skipping clutch on the changer wheel, which is driven on its lower side by the mainspring barrel, and which drives minute and hour wheel simultaneously, like every changer wheel does.

Here you can see the (upside down standing) double changer wheel. The silver colored wheel engages with the mainspring barrel, the other two drive minute and hour wheel.

The latter remains unised for display, since the direct read mechanism advances the hour disc by a lever, which sits on the cannon pinion instead of a minute indicator.

And even more interesting, the minute wheel is also driven by the changer wheel and is mounted on the open hole on the setting lever spring.

The two discs for hours (left) and minutes (right) reveal, that the hours are jumping, while the minute disc are driven slidingly.

It’s interesting, how far outside (on the left side), the hour disc protudes the movement, because this makes it possible to show hours and minutes next to each other without overlapping discs.

For the “Digitrend” models, this had the effect, that there was a large space between hour and minute display, because due to the prism, the numbers had to be shown from the lower (at 6 o’clock) part of the disc and not from the center of the movement.

In the lab

Timegrapher result

For a pin lever movement, assembled out of three broken ones, the timegrapher result is acceptable. The big amplitude difference between vertical and horizontal position are probably caused by the ruby-less bearings of the balance wheel pivots.

Technical data

Usage gallery