Motor for rotating platform

Replies

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  Al-Otaiby

  The way that I've seen it done for smaller purposes is to use a sprocket under your rotating platform and drive it with a chain from the side.
  To make it simple you can use Castor wheels that rotate on the edge of the platform.
  In the center of the platform you can put a shaft to fit the sprocket to and then you can get a housing to fit a bearing on the top and mount the other housing in the floor.
  The nice thing about a housing is that you just need to hold the outside and you can use a pipe if you wanted.
  You could also clamp is between two pieces of plastic or wood. It is just to hold the shaft in place. If you really want you can mount a solid shaft to the platform and cement a pipe in the floor and have the shaft rest in the pipe and just fill the sides with grease. The wheels will take the weight and the shaft will stay in place and rotate the platform with the sprocket.
  I would use a DC motor at you can easily change direction. You just have to swop the wires by using two sets of car relays to either have the wires one way round or the other and then you can use a car battery to power it up. A wiper motor from a Mercedes truck is a very good motor to use. But in your case the same concept might apply, however, the motor and shaft shall differ!
  I hope these info where useful, I gathered it with a help of my mate.
• 

  Al-Otaiby

  By the way,
  I managed to find this motor which would suite you:
  
  1PT - 3,000 LB Gear Tilt Positioner 1PT-100
  Load Capacity*: 3,200-1,200 lbs (0"-18" from chuck face)
  Rotation: 18,500 in-lbs turning torque;
  Tilting Torque: 35,000 in-lbs
  Tilting Speed: 0.09-0.9 RPM (135° in 35 seconds)
  Height Adjustability: 28"-48" center height adjustment in 5" increments; 34"-54" turntable working heights in 5" increments; (taller height range options available)
  Footprint: 64" x 48¼ " x 43" (height)
  Controls: 6-Button Pendant, c/w power on/off w/light, variable speed rotation, bi-directional rotation, tilt-up, tilt-down and variable speed tilting functions on 30 ft of heavy duty cable
  Power Requirements: 230, 3-ph, 20A input (110V, 1-ph, 15A available), alternative input power compatibility optional
  Rotation Speed: 0.2-2.2 RPM
  Turning Torque: 20,000 in-lbs
  Equipment Mass: 2,650 lbs (excluding gripper)
  Gripper Options: 26" diameter chuck mount plate accepts 16", 25" lathe style chucks and 25"-45" welding grippers; larger diameter chuck plate optional
  Ground Capacity: 750 Amp Rotary Ground (standard), 1500+ Amp optional
  
  Its originally a welding positioner motor, but if you managed to get the motor itself, that would be fine
  
  Source: #-Link-Snipped-#
• 

  Mr Zakaria

  Thanx Al-Otaiby and ur mate for the thought and quick response.
  I'm trying to build a tracker which later will have low operating power and high precision.
  So, actually i'm thinking to make a platform which is made of rectangular frame by connecting I-beams and put the four wheels at the corner of the rectangular frame.
  The solar module will be place flat on top of the frame. The module will not be tilted, it will be only rotated according to the sun azimuth motion
  The idea is to put directly electric motor attached to one or two of the wheels so that i can use the torque to rotate the platform.
  I'm also thinking to make it modular for example i want to play with the size of the module. That means with different radius of the rotation.
  If you can help me find a way or to calculate the motor needed, this will be really helpful. The calculation will help me if i want to change the radius of the rotation and size of the module. The information that i have is the mass of the frame and solar module, the radius, min and max tangential speed of sun and the motor can locate according to sun in this precision of 0.01°
  Thank you so much again Al-Otaiby and ur mate
• 

  Mr Zakaria

  btw, your idea is very good and i can use the concept as an alternative.
  Could you please tell me how you come to choosing the motor?
  What calculation should i perform to get to that?
  
  Thank you in advance
• 

  Al-Otaiby

  Speed is controllable by gears, belts or chains,
  I did a rough calculation ( not a precise ones) just to ensure that the shaft won't break or crack during rotation! because you are having, a 4 Tons weight on a 10m diameter platform, I took into consideration the tensile strength and the weight on the shaft 😉 btw, such motors (as ones on the welding positioners) will suit your need!