Graphic of a single breech-connection
The older, rather simple transmission system, was the so-called broek- or breech-system. Each key is attached to a flexible steel wire that is pulled down when a key is struck. A second wire runs from the clapper to a point fixed on the wall of the bell chamber. Both wires are looped in the center. When the key is depressed it pulls the upper wire down and causes the clapper to swing towards the inner wall of the bell. On large bells, gravity is sufficient to pull the clapper back from the bell but smaller bells are normally fitted with return springs to pull it back immediately after the stroke, so that the bell can continue to ring.
Although the traditional carillon keyboard shares some similarities with other keyboard instruments, its playing technique is unique. Hand playing is done with a keyboard called baton keyboard or stokkenklavier. Similar to a piano, the carillon keyboard has short chromatic keys above the larger diatonic ones but the carillon keys are wooden levers, rounded at the playing end. These keys are depressed by the carillonneur's closed fist. In addition, one to two octaves of pedal keys (similar to the organ pedal) for the heavy bass bells are present. These are played with the feet. This causes the corresponding manual keys above to be pulled down. Each key is connected to a bell by means of a system of wires. Although the keys are played with a closed fist, the carillonneur does not "pound" or "beat" the keys. The playing action should sensitive enough to play with a minimum of effort and allow him to control dynamics and phrasing by variation of touch
The measurements of the breech-system must be carefully calculated. To facilitate precise playing, the keyboard should be located close to the bells in order to keep the mechanical connections as short as possible. Each key is provided with an adjuster above the keyboard which allows the performer to neutralize the effects of expansion and contraction caused by variations in air temperature of each metal wire.
The broek-system in the Zuidertoren in Amsterdam
The entire mechanical system was constructed by carillon makers and not by the bell founders. Their work was fundamental for a general harmonious sound of the carillon and a comfortable playing. The proper connection of clappers to the keyboard included the correct "trimming" for a proper interplay of the system as well as the connection of the hammers to the drum for the automatic chiming (see below). Thus, the most successful carillon makers were highly regarded for their expertise in this field. The most famous carillon makers in the 17th century were Juriaan Sprakel in Zutphen (he fit the Hemony carillon in the Dom tower in Utrecht, 1664) and his cousin Willem as well as Jan van Call in Nijmegen, who erected the automatic chiming system in the Nieuwe Kerk in Delft. Naturally, the great master of all things relating to the carillon was Jacob van Eyck, who inspected and fitted several carillons. Van Eyck required the help of colleagues and craftsmen due to his blindness.
To the left is a scheme of a bell connected with a bell-crank or
tumbler (right side). The downward movement of the key (below)
is transferred into a lateral one by the tumbler at right angles
to each other. The clapper is pulled to the sound bow, thereby
striking the bell. The return spring (left side) pulls back the
clapper to its original position immediately after the stroke.
Obviously, early 17th-century carillons were difficult to play, and they demanded considerable strength. To some degree, the sheer physical effort necessary prevented the carillonneur from fully concentrating on the dynamics and subtleties of his performance. Complaints about heavy keyboard action were documented in reports about newly installed carillons. This spurred improvements mainly in trimming of the system.
However, it took more than two hundred years, after a period of a gradual decline of the carillon art and the loss of bell tuning skills, before the most significant improvements in playing could be developed. Jef Denyn (1862-1941), from 1887 municipal carillonneur at Saint Rombouts in Mechelen, realized that it was first necessary to improve the instrument itself, making the interaction between the keyboard and the bells quicker and more sensitive. This required considerable changes in the mechanical system in which the use of so-called "tuimels" or "tumblers" were of great importance.
Another improvement was the introduction of return springs for the clappers, typically in the form of coiled leaf springs. The springs force the clapper to release the bell immediately after the stroke which enables the bell to ring out.
Apart from a more sensitive playing action, return springs permit a single note to be repeated in rapid succession, producing the tremolando, a technique which is useful for prolonging the shorter frequencies of the small "treble" bells in an artistic manner. The tremolando was perhaps the most typical element of Jef Denyn's newly developed "Flemish style" with its strong contrasts, virtuoso passages and free but perfectly controlled rhythms: a new "romanticism" in the art of carillon-playing hitherto unknown.