Slewing Drives Review

I maintain and repair slewing drives, motors and gearboxes on BMU roof cranes. They aren't the particular style that your link shows.

What information are you looking for? Is it specific to the style you linked to or just slewing drives in general?

Bryan

Hi Bryan, The goal is to help engineers understand what these products are and how they are used. I think it would be best to cover slewing rings in general but I also think your experience and knowledge of slewing rings for roof cranes would be indispensable. Anything you can share would be very helpful. Thanks!

I think I would contact customers who have bought and are using these drives and request a picture and brief explanation of how it's being used, any suggestions for improvement or additions to the design, any problems installing or fitment....and build a database of contacts for how certain obstacles were overcome in adapting existing models to field deployment and any failures that have occurred to existing drives and the causes...I don't know what your time or budget constraints are but if I were you I would do this in person if possible...

In your presentation only the worm gear drive is presented. In many applications the drive is with spur gears when the backlash is acceptable within limits. The worm gear drive is mainly in rotational high precision positioning. In several application the auto lock of the worm gear is NOT wished since in a no active situation the rotation under external loads is required: cranes for instance where a free orientation under wind load is a must. Of course it is also possible to disengage the drive for such situations but I did not see it.

Slewing drives are a specialty type of gearbox packaged with a motor. Slewing drives are normally used with slewing ring bearings (which may or may not be incorporated into the drive package) to provide rotary motion and can can accommodate axial, radial and moment loads.Most slewing drives are single axis, meaning they only rotate around one axis. However, there are also dual axis drives that rotate around two axes. Dual axis slewing drives are basically two single axis drives mounted together at 90 degrees. Dual axis drives usually incorporate slewing ring bearings and are used for applications requiring multi-axis positioning, such as satellite dishes. Slewing drives/bearings have a series of radial holes for mounting to the object that rotates, and do not need to be mounted to a shaft, unlike most rotary bearings. Hope this helps.

To tell you the truth I'm not sure exactly how I can be of help.

The slewing action on the BMU roof cranes use a ring gear with external teeth and there are two motors with pinion gears that drive the ring gear.

There are two motors for redundancy because these cranes carry 2 workers over the side of the building so they can perform maintenance on the windows and exterior of the building.

The motors are controlled by a VFD connected to a PLC where the drive receives programming from the PLC program variables. It's a relatively simple design and is able to rotate the BMU, fully extended (approx. 60 -80 ft.) in 25 MPH winds.

If you have any questions, please feel free to contact me through this thread or you can PM me.

Bryan