Hi, First time here and a bit of a leftfield question, but if anyone will be able to give the answer I suspect it will be you guys! We're building a large scale turntable for an installation and have been thinking about the possibility of a slewing ring. It won't have to turn much weight (probably about 20kg) and we aim to use a motor to rotate it. This is the ring we're looking at: Trailer Ring U01N105, which has a 945mm diameter - there is a PDF spec sheet here: http://www.nbcgroup.co.uk/assets/fi...ings/Technical Leaflet - Trailer rings LL.pdf Having had no experience with these the main question is how easy are these to turn? I know one person's idea of easy is very different to another's, so could it for example be turned by hand or a small motor? Or am I way off? Any replies and advice very much appreciated. Thanks!
My experience is on hydraulic excavators, but here goes. A good swing bearing/slewing ring/rotec bearing on a hydraulic excavator is very easy to turn. When we dismantle an excavator and remove the swing drive, a man can literally rotate the revolving frame by hand by pushing on the counter weight. If the revolving frame is not on level ground, the revolving frame will rotate so the center of gravity is at its lowest point. But to answer your question, I would think it would be easy to move by hand. If not, design an easy to attach cheater bar to rotate it. Chris Hill http://ihmusedparts.com
Thanks for replying so quickly Chris, very much appreciated. That certainly gives us a good clue and already puts me leaps ahead in terms of knowledge from where I was before lunch Guess the rotation also gets easier once they are worn in? Thanks again, thought this would be the place to get answers from experience.
My closest experience is with a small bucket truck that's turned by a small hydraulic motor through a worm gear but no other reduction. It has enough slop that I can rotate the boom by hand from the bucket easily, that's with ~300KG? weight and a nylon shim as the only bearing. I'd guess those smaller slew rings would be less than 1 foot pound of torque to rotate. I wouldn't expect a ball bearing to wear in any, the torque will be mostly related to what kind of grease is in it and how much preload is on the bearing.
Superb, All sounds very promising indeed. Thanks guys for sharing your experience and knowledge and doing it so quickly.
Balance is the key. A example is the cable cars in San Francisco. They get turned 180 degrees by hand at the ends of the line. There is a roundhouse near here built by historical group that turns the railroad cars and engines by hand to go into the various bays. I've watched 4 men turn a steam locomotive a 1/4 turn from the track to the storage bay. But as said earlier they are particular about where they stop it for balance.
I think we need to clarify something first. Your OP says a load 20kg, is that correct ..? Because if all you're looking to rotate is a total load of 20kg supported on that slewing ring (which according to the link has a maximum load capability of 45KN or about 4600kg/10,000 pounds) you could turn it with the end of your little finger so long as the turntable was mounted perfectly level and was well-lubricated. I can't see why you would need one that large simply to support the load you mention, the smallest version on that data sheet is capable of supporting 5KN (510kg/1125 pounds). As you can see I'm a bit suspicious of your numbers, and I think it's worth clarifying them before commenting further.
Thanks guys, old-iron-habit - Thanks for your reply. Balance is always the key Nige - seems like overkill I know, but can confirm it is only for approx a 20kg load - we need to rotate a small load at a specific distance from a fixed centre - looked at other ways of going about it but the slewing ring seems to go a long way towards fitting our needs straight off. Great that you guys can give more informed and straightforward answers than the people who sell these things Superb forum and thanks again for all the replies.
OK, so if all you want to rotate is a load of 20kg then why go for slewing ring that's so big physically and has a maximum capacity of 500 times what you need to move...? Wouldn't the smallest one on that data sheet do for you..? It has a maximum capacity of over 500kg and even that sounds to me like overkill TBH.
Thanks Nige, agreed - in terms of weight it is total overkill. However, I need a specific space in the centre of the ring, hence not using a smaller one. Got one on order now so fingers crossed and thanks again to everyone for all the help and advice.
Glad to help.
Just as an update, slewing ring arrived today and can indeed turn it with my little finger. Just the job and thanks again for all the solid advice.
Good to know we get it right occasionally..........