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Pillow Block/Motor Mount question — Parallax Forums

Pillow Block/Motor Mount question

NWCCTVNWCCTV Posts: 3,629
edited 2012-10-09 20:37 in General Discussion
I am in the process of grinding out and drilling my pillow blocks to go on my bot. I am curious if anyone thinks it would be a good idea to mount springs underneath the pillowblocks and motors to act as shock absorbers. I had previously thought of doing this just on the motors but figured it would be a moot point if the pillow blocks were not also supported like this. My motors weigh almost 1 pound each which is the reason I designed pillow blocks to set the axles in. The axles will be roughly 5 inches in length. Before you ask, no, I do not have drawings. I tend to design things in my head and put on paper after I figure out if it will work or not.

Comments

  • xanaduxanadu Posts: 3,347
    edited 2012-10-09 16:21
    Without a drawing I wonder how would putting springs on the motors do anything for the axles? Is it chain or direct drive between the motor and the wheel? How soft are the wheels, inflated, pneumatic,or hard? Two motors per axle?

    My $0.02 is that onboard electronics and batteries can use all the cushion they can get but excess slop in the drive train will wear it out faster.
  • NWCCTVNWCCTV Posts: 3,629
    edited 2012-10-09 16:46
    Motors mount to chassis, axles mount direct to motor, wheels are lawn mower sized. 2 motors, 2 axles, 2 pillow blocks.

    Edit: Concept was to place springs underneath motors where they bolt to chassis thus acting similar to motor mounts in autos.
  • ercoerco Posts: 20,261
    edited 2012-10-09 17:09
    Pneumatic (inflatable) tires are good for absorbing shock. Supporting the wheel shaft on the outside of the wheel really spreads the load out in abusive/shock situations, per sketch below.


    But that wasn't an option in this abuse case! http://autos.yahoo.com/blogs/motoramic/camaro-owner-records-mechanics-abusing-car-scheming-damages-152707580.html
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  • xanaduxanadu Posts: 3,347
    edited 2012-10-09 17:27
    Sounds like the whole assembly needs to move together (motor, shaft, pillow block, wheel).

    If you had a chain drive you could put suspension on the pillows and motor independently and the chain will take care of the rest. I haven't done any direct drive using axles though.
  • NWCCTVNWCCTV Posts: 3,629
    edited 2012-10-09 17:38
    xanadu wrote: »
    Sounds like the whole assembly needs to move together (motor, shaft, pillow block, wheel).



    If you had a chain drive you could put suspension on the pillows and motor independently and the chain will take care of the rest. I haven't done any direct drive using axles though.

    No, Motor, Shaft, Bearing inside pillow block, wheel.

    I understand this but it is not the way I designed it. I want as few moving parts as possible and do not want to use chain becuase they tend to rust. I am not looking for new ideas. I just want to know if using springs would be a good idea or not to support the motor/axle/wheel assembly because of the weight of the motors.
  • xanaduxanadu Posts: 3,347
    edited 2012-10-09 18:03
    Oh, gotcha. Well yeah it's a good idea to have suspension if you need it.

    What it needs are some cardan joints... Then you can bolt the motors down solid and just put springs on the pillows :) Can you make those?
  • NWCCTVNWCCTV Posts: 3,629
    edited 2012-10-09 18:09
    That is actually a good idea. Not out of the question but I am closer now than I have been in 2 years to getting a rolling chassis going and do not want to complicate it right now. I will keep that in mind for enhancements down the road.
  • W9GFOW9GFO Posts: 4,010
    edited 2012-10-09 18:14
    Here is a picture of my wheelchair based robot, it has a suspension similar to what you describe.

    IMG_1028.jpg
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  • NWCCTVNWCCTV Posts: 3,629
    edited 2012-10-09 18:15
    That is pretty hefty!!!!! Nice looking work. Is that aluminum tube?
  • xanaduxanadu Posts: 3,347
    edited 2012-10-09 18:29
    NWCCTV wrote: »
    That is actually a good idea. Not out of the question but I am closer now than I have been in 2 years to getting a rolling chassis going and do not want to complicate it right now. I will keep that in mind for enhancements down the road.

    Haha, I hear you. Mine was a very hasty job to say the least and still took too long. I'd still go with soft tires, a padded battery box, and rubber mounted electronics over suspension. Then again I don't have the means to do anything else lol...
  • W9GFOW9GFO Posts: 4,010
    edited 2012-10-09 18:36
    NWCCTV wrote: »
    That is pretty hefty!!!!! Nice looking work. Is that aluminum tube?

    No, it's all steel. I completely stripped the wheel chair, cleaned and then painted all the parts. It used to be all black. I like lighter colors so that I can actually see what I'm doing.

    It's the robot I brought to UPEW 2010. I have just last week ordered a second 55Ah battery so that I can run it off 24V. It only took two and a half years... maybe by next UPEW Expo it will be fully functional.

    small1.jpg
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  • NWCCTVNWCCTV Posts: 3,629
    edited 2012-10-09 19:05
    W9GFO wrote: »
    No, it's all steel.

    small1.jpg

    WOW. That is impressive. I was thinking steel but then thought that would be too heavy!!!!! It is a nice job though.
  • xanaduxanadu Posts: 3,347
    edited 2012-10-09 19:35
    The weight of steel @ 24v w/ 55Ah starts to trade off for price and availability nicely. There is one aspect of carrying it up or down stairs that differs of course!
  • NWCCTVNWCCTV Posts: 3,629
    edited 2012-10-09 20:37
    xanadu wrote: »
    There is one aspect of carrying it up or down stairs that differs of course!

    I guess legs would be a good addition in that case!!!
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