Saving time, money for quarry operators, OEMs

Shaft-mounted gear units are a popular choice for quarry operators and OEMs. The gear units can be mounted onto conveyor shafts, eliminating auxiliary transmission elements such as couplings, chains or belts and associated guarding. 

Compared to a solid shaft mounting method this saves time and money during assembly and achieves a more compact design. TorqLOC, available from SEW-Eurodrive, revolutionises the connection of the hollow shaft to the conveyor shaft and eliminates pitfalls associated with contact corrosion.

Historically, V-belt to gear box input shaft arrangements have been utilised on most quarry sites. The use of a V-belt between the motor and gear unit with various combinations of pulley diameters enables operators to change the input speed to the gear unit. The V-belt also acts as a sacrificial protection device during overload conditions.

The legacy solution, however, has presented requirements for extra guarding and maintenance. The adaptation of close coupled gear units and motors ? ?gearmotors? ? has diminished the  connection of motor to gear unit via a V-belt.

The availability of robust variable frequency drives can change speed electrically rather than via mechanical elements.

Gearmotors with various ?hollow? output shaft designs have been available for many years. Designers and operators have shied away from direct coupling of gearboxes because after exposure outdoors, it is difficult to remove the gearbox from the driven shaft.

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Traditionally, the connection between a gear unit hollow shaft and a conveyor shaft is made by either interlocking via key or non-positive connection with a shrink disc. However, these connection systems have disadvantages. 

Machining the conveyor shaft and the assembly is difficult due to the tolerance fits between the hollow and conveyor shafts. 

If contact corrosion occurs between hollow and conveyor shafts after extended operating time, despite all preventative measures, removing the gear unit from the conveyor shaft is difficult and may require cutting off the conveyor shaft.

The TorqLOC hollow shaft mounting system from SEW-Eurodrive is the alternative to conventional connection technologies. The system consists of a shrink disc, a stop ring and two conical bushings inserted on each side of the hollow shaft. Before mounting the gear unit onto the conveyor shaft, the conical bronze bushing is secured against axial slipping through the stop ring on the conveyor shaft.

Next, the gear unit is mounted. 

This is possible without adjustment and expenditure of force since no fits must be overcome between hollow shaft and input shaft. Next, the shrink disc is placed and the steel counter bushing is inserted. After tightening the shrink disc, the gear unit is mounted on the input shaft.

The metallic fixed protective cover shields the rotating shrink disc, thereby providing an additional means for accident prevention. Disassembly is carried out in reverse order. In this case, the gear unit is removed from the conical bushings using lifting screws.

Contact corrosion between a hollow shaft and a conveyor shaft is prevented by using TorqLOC. It offers other advantages in addition to simple assembly and the possibility of safe disassembly even after many operating hours.

TorqLOC allows the use of drawn, unprocessed material up to quality level h11 for the shaft. However, quality level h6 is mandatory for standard shrink discs. TorqLOC allows compensating shaft diameter tolerances from 0.1 to 0.15. TorqLOC eliminates the need to cut keyways or turn the solid shaft to exacting tolerances, which saves time and money.

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Besides the rated diameter, it is possible to adapt different diameters of the conveyor shaft to a hollow shaft. Conveyor shaft diameters up to rated diameter -5mm can be implemented by using the corresponding bushings. 

This allows gear unit types held in stock and different bushings to be used in machines with different input shaft diameters, thereby reducing storage space and saving storage costs.

TorqLOC is available for helical-worm, helical-bevel and parallel shaft helical gear units, which allows it to be used for output torques to 18kNm. In addition to the standard one sided mounting position of the driving shaft, a TorqLOC hollow shaft is also available for mounting shrink discs on either side. 

The TorqLOC hollow shaft mounting system comprising hollow shaft, shrink disc and steel bushing is also offered as corrosion-resistant stainless steel.