“A safe bet – Safety couplings protect your investments”


Sensitive damage in today’s industrial plants occurs quickly, regardless of whether incidents are caused by human or mechanical errors. In many cases, safety couplings are used to protect the complex and often sensitive components. JAKOB Antriebstechnik presents newly revised series that ensure higher torques and a series of unlocking safety clutches, which automatically re-engage when the direction of rotation is reversed at a slow speed.

For several decades, JAKOB Antriebstechnik has been active in the field of overload protection and torque limiter. The scope of application covers all demanding drives in mechanical engineering, from the highly dynamic servo axis of a machine tool to the overload protection of conveyor systems. Particularly in modern applications with ever-increasing degrees of automation and dynamization, machine damage not only means repair costs, but also rapidly and costly downtime, causing massive financial losses. Appropriate protection against such scenarios should therefore be a high priority nowadays.

Safety couplings from JAKOB Antriebstechnik are designed as breakpoints or overload limiters. At the center of the clutch is a robust and high-precision release mechanism with steel balls as a spring-loaded positive-locking body. The drive torque is guided by the shaft via a keyway connection or a non-positive, play-free clamping or cone connection in the centrally arranged hub. The hub is designed as a ball cage and serves to receive a driven-side flange ring, a switching disc with plate spring and the adjusting nut. Special disc springs press the balls over the pressure or indexing disc into hardened calottes of the flange ring. In normal operation, the drive torque is transmitted without play into the flange ring. For torque transmission, a compensating element (metal bellows or elastomeric star), a toothed belt or pulley, or a corresponding connecting flange is attached to the flange ring. Depending on the selected compensation torque, the clutch is able to compensate for significant shaft misalignment. If the set release torque is exceeded, the flange ring rotates relative to the cage hub, the balls are pushed out of the calotte. The powertrain is interrupted within a few milliseconds. Due to the tension of the steel balls between the ball cage, hub and flange ring play-free torque transmission and high torsional rigidity are guaranteed.

As in the past, JAKOB Antriebstechnik continues to rely on its tried-and-tested modular principle in order to guarantee short delivery times with consistent quality. This system makes it possible to select the optimum design of the overload mechanism for the particular application, as well as the desired types of attachment covering almost all indirect and direct drives. For direct drives, the safety coupling to the shaft-shaft connection is supplemented by metal bellows or elastomer attachments. Recently, now the designers of JAKOB Antriebstechnik have revised numerous series, which can secure a much wider torque range now, so now a number of other applications for the proven torque limiter comes into question. The maximum release torques were doubled from 3000 to 9000 Nm. New versions are available for both indirect and direct drives. The series SKY covers indirect drives, and provides a connection by means of conical clamping sleeve respectively for the larger torques (3000-9000) by a cone-shrink disc, while the number SKW is a less expensive alternative, are transmitted in the torque by means of keyway connection, Direct drives, on the other hand, can be protected by the SKY-KS series with metal bellows coupling attachment and double-sided cone clamping. The new sizes also cover a wide range of diameters and are available for bore diameters of up to 130mm.

Of course, it is for the competent sales staff by Jakob Antriebstechnik to advise potential users in detail and to find the optimal technical solution for each problem, and to find a possible solution for unmet tasks in cooperation with customers.

Background knowledge:
The backlash-free ball detent mechanism
A patented clamping of the hardened and polished steel balls between the ball cage of the hub and the flanges of the flange ring guarantees a backlash-free torque transmission with high torsional rigidity. The mechanism acts in reversing mode equally for both directions of rotation.

The degressive spring characteristic
The function of the JAKOB safety clutches is significantly influenced by the disc springs specially developed for this application. Due to the design in the degressive characteristic curve range, the spring force decreases with increasing spring travel (switching travel), as a result of which the torque immediately drops off when responding. In conventional spring-loaded overload clutches, however, increases the spring force and the disengaging torque z. T. considerably. This results in an undefined functional behavior between response and disengagement.

The dynamic release behavior
JAKOB safety couplings are characterized by outstanding dynamic release behavior. The reason for this is the degressive spring characteristic and the minimized masses (ball and indexing disc), which are to be accelerated axially when disengaged. This guarantees that the powertrain is interrupted within a few milliseconds in the event of a collision. The product of mass and acceleration (F = m • a) results in a force that has to be added to the spring force. In conventional couplings with large mass fractions to be moved, the static disengaging torque and the switching time can increase many times over.


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