HPP 431

Description

In the 1950s and 1960s, the German manufactury Henzi und Pfaff produced first pretty well, later only simple pallet lever movements in compareatively small figures.

Even more rare than their windup movements are their selfwinding movements, starting with the caliber series 420/430 probably around 1960.

With a diameter of 29mm (12 3/4 lignes, but officially only listed with 12 lignes), it is a pretty large movement, but only the inner part of the base plate is used for the movement itself, the outer part is used for the oscillating weight.

Of course, on all important bearings, rubies were used, even for the selfwinding mechanism, which has got it bearing at position 8 o’clock.

With the directly driven center minute wheel, the HPP 431 uses the conventional, high building gear train, on which the third wheel follows, then the directly driven center seconds wheel and finally the (very filigree executed) steel escape wheel.

As escapement, a swiss pallet lever escapement is used.

The HPP already uses a screw-less anular balance, which has got two slantes legs. On caliber 431, it is beared between two Incabloc shock protections and beats slowly with 18000 A/h.

The adjustment can be made only directly at the hairspring key.

The selfwinding mechanism is implemented in an detachable module. If it is not mounted, only the bearing besides the crown wheel reveals, that it is not a windup movement.

A remarkable detail are the screws: They have not only very large screw heads, but are also very long.

The selfwinding module is attached with two screws on the gear train and mainspring barrel bridges.

The selfwinding module, too, uses ruby bearings, which promise long durability.

The rotor drives a rocking bar changer, which ensures, that the first reduction wheel always turns in the same direction, regardless in which direction the oscillating weight turns. For this, a ratchet blocks the reduction wheel in the “wrong” direction. Unfortunately, that ratchet has got a round thorn which wears out and loses its blocking functionality.

Already the second reduction wheel is led outside and engages with the crown wheel.

To disengage the selfwinding mechanism at manual winding and to preserve it agains excessive wear and tear, the second reduction wheel has got a Breguet clutch.

When only the base plate of the selfwinding module is mounted, you can see, where the engagement with the crown wheel will happen.

Here again the fully equipped selfwinding mechanism.

Both, the pawl and the rocker changer and both reduction gears are ruby-beared!

Another ruby bearing is found in the center of the oscillating weight, which is axle beared.

On the yet empty dial side, you can see the yoke keyless works.

Interestingly, the bearings for the lever and for the escape wheel show preparations for cap jewels, but the only cap jewel, which you can actually find, is on the bearing of the third wheel, where it is far less useful. Why? Probably a confusion by a former watchmaker?

The HPP uses a very simple calendar mechanism with a large, once per day revolving switching wheel, on which a finger was stamped out.

This mechanism doesn’t allow a quickset correction, and so, for any date change, you have to “crank” a lot with the crown, either forward or backward.

The cover of the calendar mechanism has got a spring mounted mandrel, which is responsible, that the date ring properly snaps and additionally, the spring doesn’t fly away.

In the lab

Timegrapher result

The crude execution of this movements shows, that it does not belong to haute horlogerie, but is “only” a mass produced movement, and the timegrapher rates prove this very well. However, with a real service, they should improve a bit.

Technical data

Usage gallery