Electromagnetic single disc brakes
Without slip-ring, Zero Backlash, Dry operation, Simple construction & Maintenance, Non-asbestos friction surface .
Application :- Textile, Packaging & printing machinery, Paper-making machinery, Welding machinnery, Machine tools, Food-processing machinery, Automation & business machinery, Book-making, Wood processing & Watch making machinery.
Torque :- 3 N-m to 2500 N-m ............... Micro-clutches from 0.3 N-m to 3 N-m**
(** Numerous custom-built variants, especially for business machines, copying machines, etc.)
Type EK-ER

VORTEX also produce EK-ER series of single disc clutches which typically work on the same principle as the EBA series but are characterized by their higher flexibility due to their metallic friction surfaces as opposed to the conventional steel-friction liner mating surfaces. They also give a higher torque for the similar size and more importantly can function even in wet environment albeit with slightly reduced torque transmission capacity.


These clutches have no slip rings and are maintenance-free. An important feature is the double magnetic flux path in the armature, which enables the force of the magnetic field to be used twice. This gives a high torque capacity with small physical dimensions and a relativity large bore.

The friction surface are of metal, making these clutches particularly acceptable from the environmental point of view because the organic friction linings containing asbestos commonly found in other single-disc clutches are eliminated. They are also suitable for wet or dry operation.

The clutches need to be run-in briefly or to be operated a few times with a speed differential before they will develop their full rated torque. In dry operation they are unaffected by oil or grease.

A diaphragm spring is used for transmitting the torque without radial float. It is attracted to the face of the armature at 3 or 6 points and secured to the mating component (driving or driven gearwheel, flange, etc.). by 3 bolts.


The clutch comprises a stationary magnet body containing the coil, rotor and armature.

The magnet body is bolted to the machine housing whereas the rotor is mounted on the shaft to be coupled.

It rotates in the stationary magnet body with a small radial air gap. The armature is secured to the face of the driving or driven part by 3 bolts.

The torque is transmitted by the rotor and the armature; it is unimportant whether the rotor or armature is driving or driven, it simply depends on the mounting arrangements of the particular application.

Good central alignment of the three parts (magnet body, rotor and armature) is necessary in accordance with the tolerance stated in "Design notes" (paragraph 4 and 5).


1. These single-disc clutches have metal friction faces and are suitable for dry or wet operation. The following criteria ....affect the choice of suitable operating conditions :

Dry operation

In dry operation, single-disc clutches have high torque capacities and short operating times. The actual torque values are given in the Selection tables. However, the friction surfaces are subject to wear in normal use and therefore have a finite life.
Should small quantities of oil or grease contaminate the friction surfaces in dry operation, the torque capacity will be reduced briefly but will be regained after a few operations involving slipping. If there is no slipping, i.e. frictional work, this self-cleaning will not occur.

When installing a new clutch or brake the friction surfaces should be cleaned to remove the anti-corrosion oil film applied, prior to dispatch otherwise the stated torque values will not be attained. If there is constant heavy contamination by oil or grease there will be a reduction in torque capacity.

Wet operation

Single-disc clutches lubricated with oil or grease have lower torque capacities and longer operating times. Provided the lubrication is adequate according to the energy dissipation diagrams however, they are completely free from wear therefore require absolutely no maintenance. More detailed design notes regarding wet operation are available on request.

2. The torque loading of the clutches is transferred to the shaft using keys to DIN 68856, Sheet 2. In the case of small ....types with both up to 8 mm the connection between shaft and rotor is made by pinning, bonding or interference fit. ....The rotor must be located axially on the shaft.

3. The clutch can be installed either horizontally or vertically with the armature at the top or bottom, as required.

4. When clutches are used for connecting two shafts the value of center offset must be within specified limits for ....which please contact our design team, for your rough reference these values are also given in the tables. If the ....required accuracy cannot be obtained, the rotor and armature must be located centrally on one shaft extension and ....the torque transmitted to the second shaft extension via a flexible coupling.

A radial air gap must be left between the rotor and the magnet body otherwise both will suffer damage. This is why the stated value of centre offset must never be exceeded. Central alignment is provided by diameters D4 and D3 on the magnet body. It is preferable for the central alignment to be on an anti-friction bearing in D3 enabling the axial position of the magnet body to the rotor to be fixed at the same time.
Central alignment of the armature is provided by the 3 fixing bolts only. It must not be centered or located in other way. However, it is essential for the tapped holes to be accurate in pitch and pitch circle diameter.

5. Fitting the armature

The armature is bolted to the mating part (flange, belt pulley, etc.) at 3 points. There are appropriate through-holes in the diaphragm spring and counter bores for the bolt heads; socket and screws to DIN 84 or hexagon socket-head screws to DIN 7984/6912 should be used. Locking of the screws to the diaphragm is impractical; they must therefore be secured by adhesive, caulking or locknuts.

When the armature is fitted, the diaphragm spring is preloaded in the axial direction in order to produce rapid operation of the clutch. This also ensures that the armature does not rattle or rub against the rotor or brake disc.

This preloading is unnecessary on the electromagnet types of the clutches of sizes EK-ER 0.05 and 0.16 in special cases the sizes EK-ER 0.5 to 125 can also be used without preloading, to utilize the greater travel and hence achieve long intervals between readjustments in dry operation.


Limited external diameters with internal mounting arrangement in applications having space constraint are also possible to suite customer machine design requirements. VORTEX can also offer other custom built variations for which you are requested to contact our design team.