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  1. Is there an alternative to using pillow blocks?

    I'm currently using 2 pillow blocks side by side to hold my drive shaft. The pillow blocks are constantly slipping out of alignment one way or the other. What I'm wondering is, are you guys using anything else to mount your shafts? Click image for larger version. 

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  2. #2

    Re: Is there an alternative to using pillow blocks?

    If they are slipping, then your mount is not strong enough.
    Perhaps attempt to machine some grooves and edges that are exactly the size of the pillow block, so that there's something to hold it in place?

    There are lots of different kinds of couplings and mounts that can be used, and bearings pressed into machined cavities. There are also MIG welders for making things stick in place ;-)
    It all depends on how hard you want to work for it.

  3. Re: Is there an alternative to using pillow blocks?

    Thanks,
    We are going to see if we can weld the bearing to the housing, if that doesn't work, I think we'll weld a bearing in a piece of plate and try that.

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    Re: Is there an alternative to using pillow blocks?

    There is also the option of mounting the chain sprocket and the track sprocket on a common hub (machined length of pipe or rod stock) with internal tapered pin bearings that ride on a non-rotating/passive axle (with or without suspension). It works quite well for all sorts of bikes, scooters, motorcycles, and for the non-powered wheels of cars, trucks, etc.
    Please pardon the pedantry... and the profanity... and the convoluted speech pattern...
    "You have failed me, Brain!"
    bleh

  5. #5

    Re: Is there an alternative to using pillow blocks?

    I wouldn't weld a bearing. That will very likely ruin the bearing (and set the lubricating grease on fire.)
    I thought the problem was that the pillow block moved, not that the bearing moved in the block.

    If the problem is that the bearing moves in the pillow block, then you need a tighter-fitting pillow block and bearing.
    Also, it is often the case that you'll heat the bearing so it expands, then use a press to push the bearing onto a shaft, and when it cools, it will be very strongly attached to the shaft.
    Then push the bearing into the pillow block; again probably using press fit.
    This requires very tight tolerances, and, most importantly, it must be very snug, and you will likely need a press to get enough force to actually put it on there.

    I suppose another option to fix the bearing in the block would be a pillow block with a C-like housing that clamps with big screws? I haven't seen any of those, but I imagine they must exist.

  6. Re: Is there an alternative to using pillow blocks?

    Thanks guys,
    Every pillow block or mounted bearing I've seen has some sort of self aligning feature. I've bought 2 different brands and they both shift out of place when I tension the track.

  7. #7

    Re: Is there an alternative to using pillow blocks?

    Are you using a single bearing for cantilevering the axle? If so, you probably want to add a second bearing on that axle, a little bit out from the first one. (The bigger distane, the better!)
    The torsional/twist forces on a single bearing are very strong, because the axle gives it a strong moment and the bearing edge is close to the center of rotation. Adding a second bearing a bit out moves the "center of rotation" a lot and thus the local torque is much less.

  8. Re: Is there an alternative to using pillow blocks?

    Quote Originally Posted by jwatte View Post
    Are you using a single bearing for cantilevering the axle? If so, you probably want to add a second bearing on that axle, a little bit out from the first one. (The bigger distane, the better!)
    The torsional/twist forces on a single bearing are very strong, because the axle gives it a strong moment and the bearing edge is close to the center of rotation. Adding a second bearing a bit out moves the "center of rotation" a lot and thus the local torque is much less.
    On my original post is a picture of the application. I have the 2 pillow blocks side by side and the wheel and sprocket are mounted to the shaft on the outside. I know that the pillow blocks are meant for the the 2 to be spaced and the the sprockets mounted to the center but this is not possible in my case

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    Re: Is there an alternative to using pillow blocks?

    The image shows two bottom mounted pillow blocks on the frame holding the axle to the frame.

    If 'self aligning' feature is oblong mounting holes of the pillow block that allows it to slide perpendicular to the shaft, then you simply need to machine into, or weld onto, the frame some sort of rigid stop/detent/protrusion to prevent the pillow blocks sliding as the track is tensioned. Bolts alone will not be enough to prevent the pillow block sliding in the oblong holes. Trying to weld cast iron is not easy/recommended, and many cheap pillow blocks have cast iron housings, so welding the pillow block direct to the frame is not likely to work.
    Please pardon the pedantry... and the profanity... and the convoluted speech pattern...
    "You have failed me, Brain!"
    bleh

  10. Re: Is there an alternative to using pillow blocks?

    Quote Originally Posted by tician View Post
    The image shows two bottom mounted pillow blocks on the frame holding the axle to the frame.

    If 'self aligning' feature is oblong mounting holes of the pillow block that allows it to slide perpendicular to the shaft, then you simply need to machine into, or weld onto, the frame some sort of rigid stop/detent/protrusion to prevent the pillow blocks sliding as the track is tensioned. Bolts alone will not be enough to prevent the pillow block sliding in the oblong holes. Trying to weld cast iron is not easy/recommended, and many cheap pillow blocks have cast iron housings, so welding the pillow block direct to the frame is not likely to work.
    Thanks tician, It is the bearings that are moving out of place inside the housing. When I spoke to the bearing people, they said it was common for them to shift but unlikely if I'm using 2.

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