FEATURE CLUTCHES, BRAKES & COUPLINGS
BRAKING SAFELY R
Safety brakes from mayr power transmission have been chosen to safeguard the gravity-loaded axes of automated robot welding systems
OBA-topstop safety brakes from mayr power transmission have been
selected by CLOOS, one of the leading companies in welding technology. Dirk Haubrich, head of mechanical design at CLOOS, takes up the story: “mayr brakes are used in our large, automated robot welding systems, meaning everywhere thick steel plates are welded together – for construction machines, railways or tractors, for example. Amongst other things, these brakes are installed in our gravity-loaded stroke axes. From a certain size or a certain weight, a redundant system is required. The ROBA-topstop brakes act as a second brake in the safety system and ensure that the 2-2.5-tonne loads do not drop. They allow us to guarantee the safety of people and machines.” The brakes, which can also be used for eccentrically-loaded axes of rotation, are generally integrated into the motor adapter of STÖBER gear units. These are supplied in modified form so that the brake with plug-in coupling replaces the motor adapter otherwise used. STÖBER has designated this
modified product ServoStop. Gear units with integrated ServoStop brakes can be combined with almost all gear units. “As we use the motor gear units in all
installation positions, we place particularly high requirements on the tightness of the motor adapter,” added Haubrich. “We have applications on which more than 20 litres of gear oil press down on the motor adapter seal from above. No oil may leak from the gear unit into the brake, as the consequences would be disastrous.” For this reason, mayr power transmission supplies specially-adapted and designed safety brakes to STÖBER Antriebstechnik.
SAFETY SOLUTIONS As ROBA-topstop brake systems guarantee the safety of people and materials in gravity-loaded axes, they have to work reliably. As a result, they have been subjected to examination by the Deutsche Gesetzliche Unfallversicherung (German Statutory Accident Insurance; DGUV). This examination confirms that the brake equipment is a ‘tried and tested component’ in terms of Category 1 in
accordance with DIN EN ISO 13849-1. The company executes a comprehensive
final inspection as well as numerous quality assurance measures. Every single safety brake which leaves the plant must have passed a 100% inspection after full assembly and adjustment. mayr has, in fact, developed a final inspection test stand especially for ROBA-topstop safety brakes. Here, function-relevant parameters such as pull-in and drop-out voltage, coil resistance, the dielectric strength of the coil and the proper function of the switching condition monitoring system are determined. Furthermore, the brake is tested at high voltages for shorted coils. The braking torque in clockwise and counter-clockwise direction is also measured. On safety-critical applications, it is important that the braking torque is correct. The company would be able to recognise any deviations immediately during the braking torque measurements.
mayr power transmission
www.mayr.com
CRANE RE-DESIGN BENEFITS FROM INNOVATIVE COUPLING SOLUTION
A main drive engine plus a separate crane engine to power the lifting mechanisms were a design feature of the machines built by a well-know crane manufacturer. But, in order to reduce the cost and weight, the company decided to eliminate the second engine so that the power required for the superstructure would be derived from a power take-off using the distributor gear. The driving torque required would then be transmitted via gear shafts to the hydraulic unit used to lift the superstructure. Under testing, however, severe vibration was encountered during
operation and, while an innovative coupling solution was needed, there was no space in the new design for this. REICH-KUPPLUNGEN engineers were therefore challenged to devise a compact customer-specific
solution that exhibited the torsional stiffness required. Not only did the coupling need to be compact, but it had to be capable of dealing with a wide torque band, ranging from the torque generated at idle speeds through to that produced under full power conditions. To meet the requirements, REICH’s GUR 45-8 drive coupling was
selected as the low stiffness characteristics exhibited by it in the lower load range ensure that torsional vibrations are kept below critical levels at no-load speed. Thanks to the progressive nature of this coupling type, the stiffness
of the coupling rises as torque transmission increases. This is why the GUR 45-8 is particularly suited for applications where loads tend to increase in line with rotational speeds. Being versatile, the GUR 45-8’s can be used in a variety of
applications. As a robust rubber roller coupling featuring a fail-safe device, these be used in high ambient temperatures. For easy maintenance, the individual rubber elements can be replaced quickly and easily: simply pull the plugged coupling apart and insert the rollers radially from the outside into their specially shaped recesses. The GUR coupling series is available for different power ranges
and, in line with the D2C ‘Designed to Customer’ philosophy, can be customised to meet requirements, the company explains.
Reich Drive Systems UK
www.reich-uk.com od
mayr brakes are used in the large, automated robot welding systems produced by CLOOS
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APRIL 2019 | DESIGN SOLUTIONS
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