Special performance or high popularity: that's what makes an All-Stars team in sports. On the occasion of our centenary we have set our All-Stars team of cable glands from one hundred years of product history. And here is our selection.
WISKA launches its first cable gland in 1919. The box and cable gland are made of cast brass, as they are primarily used for shipbuilding. The material is inexpensive and, above all, robust and can withstand the heavy loads on board. In order to ensure that the screw connection is leak-proof, the insertion is cast directly onto the junction box.
In 1925, WISKA decided to manufacture its first plastic cable gland. The so-called "ISOSTABIL" is manufactured with the common Witworth thread. Named after its inventor Sir Joseph Whitworth, it is the first standardized thread in the world. The material used is Bakelite, a phenolic resin duroplast which is now available for industrial production. The screw connection can be sealed as follows: A sealing ring is placed between the pressure screw and the connection piece and squeezed around the cable when the screw is turned. Often, some cement is still lubricated into the screw connection in order to seal it even better.
(Product illustration from 1936. Iso-stable cable gland with WISKA's patented mounting receptacles for a "hamburger" hook wrench)
To further improve the tightness of the cable gland, the KVG ("glass fibre reinforced cone gland") gets designed in 1960. The sealing concept is adapted by providing the nozzle with a bevel inside. The bevel resembles the shape of a cone. By tightening the pressure screw, the seal is squeezed against the bevel and pressed tighter against the cable. The strain relief of the KVG is thus increased and the securing of the cable improved. The KVG is developed with the armoured conduit thread (PG), which at this time meets the current industry standard.
The KVG was successfully introduced to the market and in 1987 WISKA decided to further develop its cable glands. The "SPRINT®" cable gland shines with an extended strain relief, a larger clamping range and a new sealing concept. The sealing ring is placed together with a clamping cage at the upper end of the connection piece. The bevel, which resembles a cone, is now in the cap nut and no longer in the nozzle. By tightening, the seal is squeezed into the cap nut together with the clamping cage, thus optimizing the strain relief. The principle of the KVG is therefore reversed. At this point, the cable gland is still manufactured with a PG thread.
During the course of time, regulations change with regard to connection threads on cable glands within the EG. WISKA's answer to the new EN standard is the completely new development of the SPRINT® system. In 1997 WISKA decides to produce and sell completely new screw connections with metric threads. Most competitors only adapt their PG products to the thread and do not develop anything completely new. The idea behind the SPRINT® system is to offer the customer a modular and flexible series for various applications. Since 1989 the brand name "SPRINT®" has been successfully communicated and promoted on the market.
In 1965 it is time to fight condensation within the junction box. The "filter nozzle", which is similar to today's "VentPLUG", ensures "breathing" in the housing for the first time. The connecting piece enables an air balance between the inside of the housing and the outside air. Dust could not penetrate, also the penetration of splash water is prevented.
The "filter socket" approach is resumed and further developed in 2007. WISKA launches the world's first "breathing" cable gland on the market. The "VentGLAND®" combines pressure compensation and cable gland in one product. It prevents condensation inside the housing while at the same time protecting against dust and water. The holes inside the connection piece allow the air to circulate. The VentGLAND® is the highlight within the SPRINT® system.
A further development of the cable glands is the "MARATHON®" in 2017. Almost one hundred years ago, brass was the first choice, but today modern plastic injection moulding processes are used to optimally connect cables and cable glands. The new "MARATHON®" cable gland, for example, is characterized above all by a further developed principle of strain relief with simultaneous cable-friendly sealing properties. The clamping cage is directly connected to the seal by 2-component injection moulding. The cable gland is extremely robust, as the outer metal parts are made of zinc by pressure casting.
The filter connection already ensures a dry housing 54 years ago. Shown here in a catalogue from 1965.
A product flyer about ISOSTABIL from 1937.
The KVG in a WISKA catalogue 1960.
WISKA presents a wide variety of cable glands early on at trade fairs.
WISKA presented cable glands and installation material at the Hanover trade fair in 1950.