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ELECTROMAGNETIC SINGLE-DISC CLUTCHES, BRAKES & BEARING-MOUNTED CLUTCHES.

ELECTROMAGNETIC SINGLE-DISC CLUTCHES, BRAKES & BEARING-MOUNTED CLUTCHES
Electromagnetic Single-disc Brakes Type EAA
VORTEX ENGINEERING WORKS manufacture a wide range of Electromagnetic single-disc clutches and Brakes, which are intended for start-stop applications. They come in various types to meet different requirements. Type EAA Vortex Electromagnetic Single Face Brake Type EAA is a "Normally Off" type brake and it has two basic parts; the stator, which consists of a coil and fiction material, and the armature plate. The braking torque is produced by means of the electromagnetic force which is developed when the current flows through the brake coil, thus attracting the armature plate to the stator with friction material, thereby arresting the motion and is released immediately due to a sinusoidal wave spring, when current through the coil is cut off. These are used for dry applications only.
	FEATURES 1. These brakes are designed for simple mounting and are easily adaptable . ....to any mounting requirement as it is manufactured in varied design. 2. The sinusoidal wave spring enables a backlash free transmission, .....enabling very short response time on disengagement. 3. The friction faces are completely separated by the spring eliminating any ....drag and permitting use at very high idling speeds. 4. These units are practically maintenance free due to the stationary coil and ....highly wear resistant asbestos-free friction surface. 5. These brakes are specially treated and machined for out-of-box use and ....give the rated torque right from cycle no.1 of operation. 6. The specially heat-treated armatures give a very long operating life and ....increase the longetivity if the brake unit.

Type EB-ER VORTEX also produce EB-ER series of single disc brakes which typically work on the same principle as the EAA 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 brakes 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 relatively large bore.

The brakes 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 attached 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.
These brakes comprise a stationary magnet body and coil, in which the brake is permanently fixed and acts as the braking surface. The armature is secured to the mating part with 3 bolts.

The torque reaction during braking is taken by the mounting of the stationary magnet body, e.g. on the machine housing, motor frame or similar fixed part.

DESIGN NOTES

1. These single-disc brakes 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 brakes 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 action will not occur. When installing a new brake the friction surfaces should be cleaned to remove the anticorrosion 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 brakes lubricated with oil or grease have lower torque capacities and 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 in transferred to the shaft using keys to DIN 6885, Sheet 2. In the case of small types with bores up to 8 mm the connection between shaft and rotor is made by pinning, bonding or interference fit. The rotor must to be located axially on the shaft.

3. The magnet of the body is bolted to a stationary part of the machine and in the case of brakes; the torque is taken by this connection.

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

5. When clutches are used for connecting two shafts the value of centre 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.

In the case of brakes, the permitted centre offset tolerance of the armature relative to the magnet body is sufficiently large for the location provided by the fixing bolts of the magnet body to be adequate.

6. 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 head 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 brake. 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 brakes of sizes EB-ER 0.05 and 0.16. In special cases the sizes EB-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.

The tables do not cover the entire size available for offer, so kindly please get in touch with our design team to get more sizes at the lower-end as well as the higher-end of the torque transmission capacity. There are continuous ongoing developments to suite a wide plethora of customer applications.

SPECIAL VERSIONS

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