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RC models by Robert Holsting

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  Slewing ring.

The slewing ring (also known as slewing bearing, turntable, drehkranz) is the bearing that supports the full load of the crane incl. load, and allows it all to turn a full 360 degrees!

The slewing bearing is subjected to surprisingly strong forces, and I highly recommend that these forces are examined prior to construction, or purchase.
My tool (click here!) will help you determine these forces, and are based on an excellent brochure from SKF, which can and should be downloaded.
Link is supplied at the tool page.

  I plan to use a slewing bearing of this type: Outside gearing, single or double row of balls, high quality steel.

Normally the outer ring would be the stationary one, and the inner ring would be bolted to the crane. I might have to turn this around for design reasons, and the fact that the motor that will turn the crane will be in located in the carrier and not in the crane base. I'll get back to these details later.

  This is where the slewing bearing will go! Bolted on to the steel chassis, and a support structure not shown in this image.
A set of contacts will be developed and placed within the ring, so power and signals can be transferred to the crane from the carrier.

I will aim for a full, unlimited 360 degree capability, and about 1 rpm max slewing speed (Like the real crane).


  I was at an exhibition with my Scania heavy hauler, also there was the guy who is working on my slewing bearing.
I HAD to take it for a ride!

  My friend Jesper made this! (Jesper is called "Mr. Big" at this club: http://modeltruck.dk/index.html )
The slewing ring has about 125 steel balls, 5mm in diameter. It runs absolutely smooth, no slack what so ever, and it does not grind or bind. His skills continue to amaze me.

The total outside diameter matches the crane's width of 220mm.

  The upper side.
Now the gearing will be cut in the outer ring to match the slewing bearing on the real crane.

  The lower side.
The reduction on diameter is there to match the real crane.


  The day has come! The gear has been cut, and the slewing bearing is thereby very, very close to being complete!
The outer diameter is 220mm, and the overall thickness is 19mm.
The module 1 gear is 8mm wide.
Material: Steel. Weight ended up at 3,362kg

  Underside.

  This is not just a component, that Jesper has made.. it's a piece of art!

  First test-fit on the actual chassis and body of the crane. Now I need to make a solid platform that the bearing can rest on.. and when that's done: Drill holes and cut thread in the bearing for fitting etc.

  Platform made, and M4 holes made for fitting, and all painted!
Assembly and a lot of grease is all that's left to do.

Also in the picture: The painted chassis.


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