quality products for mechanical & fluid power: www.jbj.co.uk

quality products for mechanical & fluid power: www.jbj.co.uk

Tyre Couplings

Regardless of etymology and spelling, tire or tyre couplings,
are torsionally soft, shaft couplings with a flexible body that compensates misalignment and protects other components in the transmission system.

ATEX mechanical power transmission tyre couplings from jbj Techniques Limited
ELPEX-B® tyre couplings are highly flexible and free of torsional backlash. Because of their low torsional stiffness and damping capacity, ELPEX-B® couplings are especially suitable for coupling machines with a highly non uniform torque pattern. These tyre couplings are also suitable for connecting machines with high shaft misalignment. The elastic tyre can simply be slipped over the hub parts. The elastic tyre is held firmly in place by fitting the clamping ring. The connection transmits the torque by frictional engagement. Standard ELPEX-B® tyre coupling types are designed as shaft to shaft connections. Application-related types can be implemented on request.
Available as a catalogue standard in 15 sizes with a rated torque of between 24 Nm and 14,500 Nm. The coupling can be fitted with elastic tyres made of natural rubber for ambient temperatures of -50°C to +50°C and with elastic tyres made of chloroprene rubber for -15°C to +70°C. The chloroprene rubber tyre is marked FRAS, "Fire-resistant and Antistatic".

Benefits

The ELPEX-B® tyre coupling is suitable for horizontal and vertical mounting positions or mounting positions at any required angle. The elastic tyre is slit at the circumference and can be changed without having to move the coupled machines. The elastic tyre is fitted without backlash and gives the coupling linear torsional stiffness, thus the torsional rigidity remains constant as the load on the coupling increases. Especially suitable for reversing operation or operation with changing directions of load. The coupling parts can be arranged as required on the shafts to be connected. If the elastic tyre is irreparably damaged or worn, the metal parts can rotate freely against one another because they are not in contact with one another.

Design and Configurations

The ELPEX-B® coupling's transmission characteristic is determined essentially by the elastic tyre. The elastic tyre is manufactured from a natural rubber or a chloroprene rubber mixture with a multiply fabric insert. The elastic tyre is fastened to the hubs with bolts and two clamping rings. In type EBWT, the shaft-hub connection is achieved with taper clamping bushes, in type EBWN with finish-drilled hubs and parallel keys. The type EBWZ connects the machine shafts additionally via a detachable adaptor.

Torsional Stiffness and Damping

The damping coefficient is Ψ = 0.9.
The technical data for the elastic tyres made of natural rubber and chloroprene rubber are virtually identical. Torsional stiffness depends on the ambient temperature and the frequency and amplitude of the torsional vibration excitation. More precise torsional stiffness and damping parameters on request. With flexible couplings the manufacturing process of the rubber elements and their aging primarily influence the stiffness value CTdyn. For this reason calculation must be made with a tolerance for the dynamic stiffness of ±20%. The specified damping coefficient Ψ is a minimum value with the result that the damping performance of the coupling corresponds at least to the specified value.

Permitted Shaft Misalignment

The permitted shaft misalignment depends on the operating speed. As the speed increases, lower shaft misalignment values are permitted. The correction factors for different speeds are specified in the following table. The maximum speed for the respective coupling size must be noted. ΔKperm = ΔK1500 • FKV

Speed 500 rpm - correction factor FKV = 1.2
Speed 1000 rpm - correction factor FKV = 1.1
Speed 1500 rpm - correction factor FKV = 1.0
Speed 3000 rpm - correction factor FKV = 0.7

The restorative force (including in the axial direction) depends on speed, system torque and shaft misalignment. Restorative forces on request.

Industry Sectors

Tyre couplings are used in many sectors where transmission from a motor to the connected machine is needed. Iron and steel industry, shipbuilding, compressors, mining industry, paper manufacturing machinery, cement manufacturing installations, pump installations, electrical power generators and hoisting applications for instance.

Link to full technical specification catalogue
Additional torsionally soft, highly flexible couplings for mechanical power transmission are the ELPEX® and the ELPEX-S® series

ELPEX®

ATEX mechanical power transmission tyre couplings from jbj Techniques Limited
ELPEX® couplings are highly torsionally flexible and free of torsional backlash. Because of their low torsional stiffness and damping capacity, ELPEX couplings are especially suitable for coupling machines with a very non-uniform torque pattern. ELPEX couplings are also suitable for connecting machines with high shaft misalignment. Standard ELPEX coupling types are designed as shaft to shaft connections or flange to shaft connections.
Application-related types can be implemented on request.

The ELPEX® coupling is available in 9 sizes with a nominal torque of between 1600 Nm and 90,000 Nm. The coupling is suitable for ambient temperatures of between -40°C and +80°C. The ELPEX coupling is frequently used for high-quality drives which have to guarantee very long service life in harsh operating conditions. Examples of applications are mill drives in the cement industry, marine main and secondary drives or drives on large excavators powered by an electric motor or diesel engine.

Benefits

Like the ELPEX-B® the ELPEX® coupling is suitable for horizontal and vertical mounting positions or mounting at any required angle. The coupling parts can be arranged as required on the shafts to be connected. The split flexible rings can be changed without having to move the coupled machines. The flexible rings are mounted without backlash and give the coupling progressive torsional stiffness, i.e. torsional stiffness increases in proportion to coupling load. The ELPEX coupling is especially suitable for reversing operation or operation with changing directions of load. The coupling is delivered preassembled. The flexible rings are completely assembled. On the type ENG, the coupling halves have to be bolted together after the hub has been mounted. On the type EFG, after mounting the coupling hub, only the outer flange has to be connected to the machine. Outer flanges with different connection dimensions are available for the type EFG. If the flexible rings are irreparably damaged or worn, the metal parts can rotate freely against one another, they are not in contact with one another.

Design and Configurations

The ELPEX coupling's transmission characteristic is determined essentially by the flexible rings. The flexible rings are manufactured from a natural rubber mixture with a multiply fabric lining. The flexible rings are split so that they can be changed without having to move the coupled machines. The flexible rings are fastened to the hub with a clamping ring and to the outer flange with a clamping ring, using pins and bolts. On the EFG type, the outer flange is designed with connection dimensions for connection to e.g. a diesel engine flywheel. On ENG types, the outer flange is fitted to a second hub part, which then enables the shaft to shaft connection.

Fail-safe device of ELPEX coupling

Types ENGS and EFGS are provided with a fail-safe device. In normal operation the torsion angle of the flexible rings is smaller than the gap between the cams. In normal operation there is no metal to metal contact. If the flexible rings fail, cams transmit the torque from the inner part and outer part. These enable the coupling to be used in emergency mode for a short time. This option is frequently required e.g. in the case of marine drives.

Link to full technical specification catalogue

ELPEX-S®

ATEX mechanical power transmission tyre couplings from jbj Techniques Limited
Coupling suitable for use in potentially explosive atmospheres.

Complies with the current ATEX Directive for:
II 2GEx h IICT4 ... T3Gb
XII 2DEx h IIICT120 °C ... 160 °CDb X
I M2 Ex hMb X

(Type EST is not available in Ex version.)

ELPEX-S couplings are highly torsionally flexible and because of their low torsional stiffness and damping capacity are especially suitable for coupling machines with a highly non uniform torque pattern. Standard ELPEX-S coupling types are designed as flange to shaft connections or shaft to shaft connections. Application-related types can be implemented on request.

The ELPEX-S coupling is available as a catalog standard in 12 sizes with rated torques of between 330 Nm and 63000 Nm. The coupling is suitable for ambient temperatures of between -40 °C and +120 °C.The ELPEX-S coupling is frequently used for diesel motor drives or reciprocating compressor drives.
Because the different rubber versions enable the torsional stiffness to be adjusted to meet requirements, the coupling is also suitable for drives which require a specific and preferably pre-calculated torsional vibration behaviour setting.

Benefits

The ELPEX-S® coupling is suitable for horizontal and vertical mounting positions or mounting at any required angle. The coupling parts can be arranged as required on the shafts to be connected. ELPEX-S couplings are especially suitable for reversing operation or operation with changing directions of load. The rubber disk elements are fitted virtually without backlash and give the coupling linear torsional stiffness, i.e. the torsional stiffness remains constant even when the load on the coupling increases. There are 4 different rubber element versions with different grades of torsional stiffness available for each size from stock. On certain types the flexible rings can be changed without having to move the coupled machines. If substantial overload occurs, the rubber disk element of the coupling is irreparably damaged, the coupling throws the load and thus limits the overload for particular operating conditions. The coupling can be inserted and fitted blind e.g. in a bell housing. There are outer flanges with different connection dimensions available for each coupling size.

Design and Configurations

The rubber disk element is vulcanized onto a flange on the inside diameter. The flange can mount e.g. a taper clamping bush or a hub. On its outer diameter the rubber disk element has driving teeth, which are inserted into the outer flange. The torque is transmitted positively between the rubber disk element and the outer flange. In the type for shaft-shaft connection the outer flange is screwed to a flange hub mounted on a machine shaft.

Fail-safe device of ELPEX-S® coupling

The ELPEX-S coupling can also be designed with a fail-safe device. If the rubber disk element fails, the coupling can continue operating in emergency mode for a short time. This option is frequently required e.g. in the case of marine drives. If the rubber disk element fails, cams transmit the torque from the inner and outer parts of the fail-safe device. In normal operation the torsion angle of the rubber disk element is smaller than the gap between the cams, so there is no metal to metal contact.

Link to full technical specification catalogue
Specification of tyre couplings found in this on-line » catalogue « link
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