German watch maker Rainer Nienaber presents a new watch model- Antero, inspired by vintage car’s revolution counter. This exceptional timepiece indicates the current time by an hours hand alone. Due to its scale, the time can be read with an accuracy of approximately 5 minutes. The small seconds hand is used as a function control. The hours hand skips over the 9 on the dial (anterograde display) so that the seconds hand is not concealed.
The design of the dial and hands was adapted from a technical measuring instrument from the 1940s. A manually wound ETA/Unitas 6497 movement with a power reserve of more than 40 hours ensures that this unusual timepiece runs smoothly. The 42 mm stainless steel casing is 12 mm deep and fitted with two sapphire glasses. The upper glass has an anti-reflective coating.
Retrograde Vs Anterograde
In a retrograde time display, the retrograde hand only sweeps an arc or segment of a circle. During its travel, a spring is tensioned which causes the hand to jump back to its starting position when it reaches the end of its scale. This spring naturally restrains the additional wheels in the mechanism so that the unavoidable play between the gear teeth is permanently taken up in opposition to the direction of rotation.
With the appropriate mechanism, any hand can be given a retrograde display. Power reserve displays, for example, usually have a retrograde configuration, but do not return with a jump: these hands usually move back slowly as the mainspring unwinds.
Anterograde means “directed forwards”. Either a spatial or a temporal dimension may be implied by this. In an anterograde time display, too, the hand only sweeps an arc or segment of a circle. However, it jumps over part of the scale, for example, to avoid obscuring part of the dial. In this case too, a spring is tensioned in the course of the hand’s travel, and the play between the gear teeth is taken up in opposition to the direction of rotation.
However, this spring must switch over at the right moment from TENSION to COMPRESSION in order to cause the hand to jump forwards. But in this case, the play between the teeth is taken up in the same direction as the direction of rotation and the extra spring must first switch back to COMPRESSION.
This occurs in the first hour after the hand has jumped. In this anterograde time display, the hand sweeps an arc of 26° in each hour; except in the first hour after the jump, when it sweeps an arc of 23°, the distance required by the spring to switch over from COMPRESSION back to TENSION.