Escapement

The inhibition (formerly also transition; double échappement; . Escapement engl ) is that assembly in mechanical clocks, which provides the connection between the gear train and the regulator (such as the pendulum). It consists usually of the escapement ( escape wheel, ratchet wheel or escape wheel ) and the Hemmstück (anchor, calm piece ). The regulator causes about engaging the escapement Hemmstück intermittent stop ( " inhibit " ) of the gears and thus moderates the regular functioning of the clock. In the reverse direction it receives energy ( elevation, pulse ) in order not to stand still. A pendulum is periodically " lifted ".

The invention of three methods of inhibition achieved English watchmakers between about 1685 and 1720.

• 3.1 Graham escapement
• 3.2 Amant inhibition (also: pin inhibition, inhibition scissors, Mannhardt gear)
• 3.3 cylinder escapement
• 3.4 duplex escapement

• 4.1 Swiss lever escapement
• 4.2 Glashütte lever escapement
• 4.3 pin lever escapement
• 4.4 English lever escapement or pointed tooth lever escapement
• 4.5 Co-Axial escapement
• 4.6 chronometer escapement
• 4.7 gravity escapement of Denison ( Westminster gear)
• 4.8 gravity escapement of Riefler

Types

Known are about 250 different designs which can be classified according to their function in three types, which also reflect the chronology of their development with increasing accuracy of watches. It is to be

• Return end inhibitions,
• Dormant inhibitions and
• Free inhibitions,

Most important of which solutions are described.

Return end inhibition

When returning escapement the escape wheel is not only stopped periodically, but it suffers, like all the rest of gear train, each time caused by the regulator small reverse rotation (hence the term " loop back " inhibition). In this way, the driving force determined over a large part of the oscillation, the oscillation period of the gait controller with, and unequal driving force causes a transition fault.

Verge escapement

A mechanical clock with verge escapement differs from the first mechanical clock with Foliot only through their equipment with a regulator instead of the Foliots. The on the shaft two (spindle) attached to each other angularly offset plates ( inhibition cloth, spinning Dell Appen ) engage alternately as in the escape wheel ( here crown wheel ) so that it is a tooth rotates at each oscillation of the speed controller on. It rotates in each half-cycle by half a tooth pitch and has an odd number of teeth: 180 ° with respect to a tooth, there is a tooth gap.

The Foliot was in the last third of the 17th century, replaced by the pendulum according to theoretical groundwork by Huygens. The verge escapement requires large deflections due to the short lever arm of the cloth. Therefore, it is only suitable for light and short pendulum, which are prone to failures as little decisive end, heavy and long pendulum. However, of greatest importance was the combination of the verge escapement with the supported by a spiral spring balance at the beginning of the 17th century. The balance wheel oscillates more stable the greater her rash is. This watches were truly mobile, they could be worn on the body ( bag watches).

The verge escapement were still used in pocket watches to the first third of the 19th century, when stationary clocks (eg Morbier clocks ) to about 1860.

Hook inhibition or relapse escapement

The lever escapement was invented in 1676 by ​​Robert Hooke and introduced in 1680 by William Clement in the watch technology. Instead of tabs on the spindle (spindle inhibition, see above) are hook to an anchor - the anchor hook - attached. The hooks engage radially (the Sami axial) in the escapement ( escape wheel here ). Their mutual distance corresponding to an odd multiple of a half tooth pitch of the rotor wheel which continues to rotate at each half- oscillation of the speed controller by half a tooth pitch. The first decision taken by a particular tooth hook is the entrance hook, the other is the output hook. The hooks are further away than the lobe of its axis of rotation. Thus, the required rotation rash is small, and you can use longer pendulums, which are less prone to failure due to their severity. Clocks with an anchor can also be built flat, since the rotational axis of the armature (and hence the gear knob) is no longer as the spindle by 90 ° relative to all other waves of the movement. The hooks inhibition suppressed the early 19th century, the verge escapement with pendulum clocks.

The anchor is a crafted from a solid workpiece, which is mounted on the shaft of the balance wheel. At clocks having separate shaft, when the pendulum is suspended from a thread or a thin leaf spring and is connected to a bracket fixed to the armature shaft of the armature. With inexpensive watches (eg Black Forest Clock ), a simple sheet anchor was used from about the middle of the 19th century. The output hook is approximately at right angles, slightly more (to create a presumption, see Dormant inhibition) of the input hook bent from sheet metal.

Dormant inhibition

The inhibition Resting the escape is only periodically stopped by the escapement. It undergoes no turning back during further rotation of the gear knob on the supplement sheet, the rest of his way to repentance. Those areas on the hook of the anchor, which in the resting phase of the escape wheel in contact with one of his teeth, are part of a cylindrical surface whose axis is the shaft of the gear knob or the armature identical. The hooks rub at this stage on the tooth, making the gear knob, the lower is less than return Leading inhibition and less affected the friction coefficient. The contact surfaces have large material hardness ( gem - pallets) and oiled.

When returning leader inhibition the escapement drives the regulator after the reversal of reverse rotation to forward rotation until the end of the hook procedure. This lack of inhibition in the Resting possibility of energy transfer to the regulator is taken from the uplift. The engagement is completed in two steps. After the contact end between the tooth and the tooth tip cylindrical surface slides over an inclined surface ( lifting surface ) on the hook or hooks on a sloping surface on the tooth. The hook is thereby pushed away radially from the escape wheel. The armature is rotated about its axis and accelerates the speed controller. A pendulum as a regulator receives a slightly larger rash, it is also lifted.

Graham escapement

The Graham escapement is a grinding, stationary escapement and was developed in the early 18th century by George Graham, because of the idea of ​​the same elevation, which is attributed to the clockmaker Vulliamy. They carrying two pallets, whose outer and inner surfaces are concentric to the anchor pivot. The surface facing towards the wheel, called the lifting surface is slanted at a certain angle, and with it the drive, which receives the adjustment member is defined. The Ankerradzähne are tapered and undercut to allow the escape wheel moves freely and nothing stuck. During the complement arc of the tooth tip rubs on the calm surface of the pallet and the wheel stands still.

All inhibitions with rubbing peace based on the principle of Graham and her are consequently very similar.

Amant inhibition (also: pin inhibition, inhibition scissors, Mannhardt gear)

When Amant inhibition of the pivot point of the armature is relatively far from the center of rotation of the escape wheel. Thus, the anchor arms are elongated and have a small opening angle. The hooks engage in a axis-parallel pins on the non-toothed escape wheel. The input hook acting radially from the inside to the outside on the pins, the output of the hook from outside to inside. The Amant inhibition allows a very precise rate and was often used for tower clocks.

Cylinder escapement

The cylinder escapement has instead of an anchor a cylinder with cutouts, called passages. The cylinder engages only one tooth ( half pitch ) of the escape wheel, and consequently has a very small diameter. This inhibition was invented by English watchmaker Thomas Tompion in 1695 and 1720 improved significantly by George Graham. Due to the extremely high demands on the manufacturing accuracy it was not established until about 100 years later in greater numbers. It replaced the spindle inhibition from in portable timepieces.

The escape wheel has crown-like shape, its functional elements for inhibiting and lifting - the shoes - are located in a second plane. The toe has been in the resting phase contact with the cylinder, the outer side of shoe is designed as a lifting surface. A tooth shoe has space in the hollow cylinder (pipe ). The inner surface of the trimmed to slightly more than half of its circumference pipe is output stop. When turning back of the regulator part connected pipe ( gutter ) the toe is released, the escape wheel turns again, the lifting surface of the shoe acts on the output edge of the gutter. After the lifting of the next shoe falls with its tip on the outer surface of the channel ( input stop).

The cylinder escapement is provided for portable clocks with balance. To enable a particularly large amplitude of the balance, the inhibition is only a single Hemmungsradzahn (shoe). This is lifted from the wheel plane with the help of a supporting stem to the second level (dental carrier ). Thus, the cylinder will not hit the Raddorn, the cylinder is cut in the amount of the wheel plane again.

The two functional surfaces to raise - lifting surface and mating edge - spread reverse to Graham inhibition.

Duplex escapement

The escapement of the duplex escapement has two rows of teeth in two levels, the first of inhibiting, the second for the lifting. Hemmen and lifting do not find each twice, but only once per oscillation of the gear controller instead. The advantage is that the low elevation, namely, pretty much in the center position of the gear controller, that is, at the moment of his greatest kinetic energy takes place. An anchor does not exist. The Hemmzähne create a regular with the regulator coaxial cylinder ( role ), they can pass through a slot on the cylinder and allow the further rotation of the ratchet wheel. During the event, the next Hemmzahns a lifting gear meets the lifting arm ( lever stone) at the regulator and accelerates this.

The duplex escapement was invented in 1730 by Jean -Baptiste Dutertre, according to other sources in 1758 by Pierre Le Roy. It was used in pocket watches, but this was soon abandoned by the roller slot due to the in practice difficult to control passage of the Hemmzähne.

Free inhibition

For a free escapement is located between escape wheel and gear knob, another to its own axis back and forth rotating part. This part of the armature or a similar part with a different name. In the resting phase of the escape wheel, it is decoupled from the regulator and together with the escape wheel at rest. The existing at the Resting inhibition in this phase friction between the Hemmteilen omitted, the vibration of the gear controller is less disturbed, he swings "free". The necessary coupling to the regulator is present only in the phases of uplift and the next one, if Hemmzahnes against a Hemmhaken. This also low friction losses occur, so that the avoided friction between the Hemmteilen can not be entirely accounted for as profit.

Swiss lever escapement

The Swiss lever escapement comes, even though the name suggests otherwise, not from Switzerland. However, the Swiss first discovered the potential of this inhibition. In German textbooks of older generations it is often called lever escapement.

The Swiss lever escapement consists of three modules: the escapement ( escape wheel synonymous ), the armature and the lever plate. It is one of the inhibitions with shared drive, ie the drive is performed on the wheel as the anchor pallets.

The Swiss lever escapement runs, divided into parts, as follows:

• Double roller / lever disc: supplement sheet rising, then falling ( about 220 ° to 270 ° ) - Trip ( about 8 ° ) - pulse before and after the dead point ( about 30 °) - supplement sheet rising, then falling ( about 220 to 270 ° ), etc.
• Anchor: rest - Trip ( 2 ° -4 ° ) - Pulse ( approx. 10 °) - Lost Way (safety from falling off the wheel to limiting pin ) ( 30' -1 ° ) - rest

• Rad: Silence - Geometric return ( 0 ° 15 ' ) and dynamic return ( 0 ° 0'15 ) - Pulse (approx. 10 ° 30') - Outer or Inner case (1 ° -2 ° ) - rest

Glashütte lever escapement

The Glashütte lever escapement is also a piston tooth inhibition as the Swiss lever escapement, hardly oxidized only a slightly altered setting angle of covert and arched pallet stones and with an anchor from a curable and non-magnetic gold alloy whose surface and watch oil thereon. The magnetic resistance and the durability of the watch oil had a positive impact on the course error. The curvature of the pallet stone, the reduced area of ​​contact with the escapement wheel, and thus the friction. The construction-related uniform weight distribution of the anchor around the pivot point keeps the focus on the oscillation process in the same place, which theoretically results in a lower response errors. However, the tare of the anchor required some experience, as subsequently followed by a hole and attaching a limiting pin. In addition, the Swiss lever escapement achieved with its variable focus similar response errors.

Pin lever escapement

The pin-lever escapement (synonym pin lever escapement ) was developed in 1798 by Louis Perron. This could pocket watches are made with an inexpensive lever escapement, took over at the metal pins enhancement and inhibition, making the use of expensive stones could be mitigated. It was also easy to manufacture in series and has been used, among others, in watches by Georg Friedrich pin lever.

English lever escapement or pointed tooth lever escapement

Works almost the same as the Swiss lever escapement, but in contrast to this the only drive on the pallets because the Ankerradzähne are pointed. She is a previous version of the Swiss lever escapement, this however did not survive, because the pointed teeth bend or break easily, it is therefore very sensitive to impact.

Co-Axial escapement

In the co -axial locking the anchor is a lateral arm which at its end is designed essentially as the anchor of the Swiss lever escapement added. Lifting ( Drifting) is not executed by the Hemmpaletten. Here are two more pallets and another sprocket ( drive wheel ) on the escape wheel are available. One of the two engines pallets ( pallets lift ) is located on the armature ( between Hemmpaletten ), the other on the balance shaft ( above the slot in the security role ). Drifting is done in favorable moments, namely, pretty much in the center position of the gear controller, that is, in moments of his greatest kinetic energy.

This inhibition is a development of the watchmaker George Daniels. It was introduced by Omega in 1999. You should (see below) to replace the shock -prone chronometer escapement in portable timepieces.

Chronometer escapement

The chronometer escapement, the similarity of the Hemmstücks is no longer present with an anchor. The part is called here, for example, rest piece. It is a tangent to the escapement arranged arm which is mounted rotatably connected to a quasi leaf spring ( spring transition ) and has only a Hemmpalette ( hearthstone ). The function is similar to that of duplex inhibition ( see above). However, the escape wheel has only one row of teeth, each tooth is used to inhibit and to lift. During the event, the next tooth on the hearthstone a third tooth meets the lifting arm ( lever stone, stone drive ) on the regulator and accelerates this. The inhibition is terminated by a second range (tripping stone) at the regulator. About the tip of the rest piece protrudes a leaf spring ( release spring, gold nib ), which is taken from tripping stone and the rest piece takes along with the hearthstone. As the inventor of the chronometer escapement, the Frenchman Pierre Le Roy and Ferdinand Berthoud and the Englishman John Arnold and Thomas Earnshaw apply. So you furnished their length Watches (later chronometer ) that emerged in the wake of John Harrison's highly accurate clock H4 ( 1759). Chronometer be built until today, but when inhibition in portable watches the chronometer escapement is less suitable. It is too sensitive to shock. The coaxial escapement is to close this gap.

Gravity escapement of Denison ( Westminster gear)

In the gravity escapement of Denison, which is used exclusively for tower clocks, decouple two lateral lever pendulum and escapement wheel about its own weight and thus cause inhibition. The necessary energy to the pendulum is supplied by these levers are raised a little after their fall through the gear wheel so that the pendulum did not need to raise as much the next time you take away, as they then fall down. The Denisongang is used in tower clocks in England, among other things, a " double three-armed Denisongang " used in the clock tower of Big Ben at the Palace of Westminster.

Gravity escapement of Riefler

This inhibition was developed by Sigmund Riefler for precision pendulum clocks. She had Gait deviations of less than 10 ms per day, making it the most accurate mechanical inhibition that has ever been designed. Therefore, it was used until the 1960s in astronomical precision watches.