Center Pivot?

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RonRock

Member
Joined
Sep 18, 2007
Messages
18
Bobcat 331. Year 2000, 2000hrs. How can I tighten up the center pivot? When I turn and stop there is some slop that I would like to tighten up.
 

Fishfiles

Well-known member
Joined
Feb 8, 2007
Messages
1,698
The swivel (center post) as you mention is bolted to the lower and has a bracket that keeps it from turming on the top , I have seen the bolts loosen up and even come out but I really don't think that is what would cause what you refer to as slop as the center post as you call it doesn't give any rigidity to the pivot of the swing -------------------------------------------- give more detail as to what slop is -------------- I am think a few things I am thinking of --------could it be , when you swing and try to stop the machine will drift past where you intended to stop and stop eratic , this is caused by the two brake cartraiges mounted on the block of the swing motor , if it does it one way and not the other only one is bad , you can switch the two and if the problem switches sides you will know which ones is bad , an other problem could be in the slew bearing ( swing bearing ) it could have wear in it , there are grease fittings that are neglicted that will put slack in it , the bearing is checked with a dial indicator , also I have seen the bolts of the swing motor housing loosen up and give slop in the swing
 

RonRock

Member
Joined
Sep 18, 2007
Messages
18
The swivel (center post) as you mention is bolted to the lower and has a bracket that keeps it from turming on the top , I have seen the bolts loosen up and even come out but I really don't think that is what would cause what you refer to as slop as the center post as you call it doesn't give any rigidity to the pivot of the swing -------------------------------------------- give more detail as to what slop is -------------- I am think a few things I am thinking of --------could it be , when you swing and try to stop the machine will drift past where you intended to stop and stop eratic , this is caused by the two brake cartraiges mounted on the block of the swing motor , if it does it one way and not the other only one is bad , you can switch the two and if the problem switches sides you will know which ones is bad , an other problem could be in the slew bearing ( swing bearing ) it could have wear in it , there are grease fittings that are neglicted that will put slack in it , the bearing is checked with a dial indicator , also I have seen the bolts of the swing motor housing loosen up and give slop in the swing
Thanks, that gives me some things to check.
 

Land-Tech

Well-known member
Joined
May 13, 2008
Messages
160
Thanks, that gives me some things to check.
Hey, sorry this is such a late post,I have to finish up my season before I can play on the computer.Refer to the slop I mentioned in a previous thread, it feels to me that the lash between the pinion gear and the ring gear is excessive and I was hoping to maybe take a shim out or adjust the drive motor to tighten up. I have not attempted to even check to see if the motor is loose. I have been meaning to get a manual for the 331 but I've never had a serious problem with this machine so never really needed one. My 435 which I do have a manual shows the motor brakes but the 331 locks the house with a pin that manually drops down into the lower end to keep the house from swinging.Being a 1997 model I don,t think there is a brake system, just a motor coupled to a pinion. also when I swing I hear a noise that sounds to me like an incorrect lash, The slew bearing seems tight and the house doesn,t rock like it would if it were loose. The 2000 model may have an upgraded system closer to my 435 and may be quite a bit different.
Again since I have no manual or been into the machine its all guessing on my part but I plan on finding out later this winter.Hopefully it will be a simple fix (loose bolts),and not semi expensive (pinion drive bearing or brake shoes) or expensive (worn ring gear and pinion). thanks
 

Fishfiles

Well-known member
Joined
Feb 8, 2007
Messages
1,698
Hey, sorry this is such a late post,I have to finish up my season before I can play on the computer.Refer to the slop I mentioned in a previous thread, it feels to me that the lash between the pinion gear and the ring gear is excessive and I was hoping to maybe take a shim out or adjust the drive motor to tighten up. I have not attempted to even check to see if the motor is loose. I have been meaning to get a manual for the 331 but I've never had a serious problem with this machine so never really needed one. My 435 which I do have a manual shows the motor brakes but the 331 locks the house with a pin that manually drops down into the lower end to keep the house from swinging.Being a 1997 model I don,t think there is a brake system, just a motor coupled to a pinion. also when I swing I hear a noise that sounds to me like an incorrect lash, The slew bearing seems tight and the house doesn,t rock like it would if it were loose. The 2000 model may have an upgraded system closer to my 435 and may be quite a bit different.
Again since I have no manual or been into the machine its all guessing on my part but I plan on finding out later this winter.Hopefully it will be a simple fix (loose bolts),and not semi expensive (pinion drive bearing or brake shoes) or expensive (worn ring gear and pinion). thanks
The brake on a 331 swing are those two cartraiges ( non adjustable relief looking gizmos) on the manifold block that is mounted on the top side of the swing motor , they seal for over $200 each , usually I don't see two go out at the same time , when they go bad the machine will continue to swing after you let off the joy stick , if it does it one way and not the other I change the position of the two , if the problem switches direction then it shows which one is bad , ----but I don't think tht has anything to do with your problem , I have always considered the 331 were very sloppy in the swing , there are no shims between the motor and the upper
 

Land-Tech

Well-known member
Joined
May 13, 2008
Messages
160
The brake on a 331 swing are those two cartraiges ( non adjustable relief looking gizmos) on the manifold block that is mounted on the top side of the swing motor , they seal for over $200 each , usually I don't see two go out at the same time , when they go bad the machine will continue to swing after you let off the joy stick , if it does it one way and not the other I change the position of the two , if the problem switches direction then it shows which one is bad , ----but I don't think tht has anything to do with your problem , I have always considered the 331 were very sloppy in the swing , there are no shims between the motor and the upper
Thanks for the reply and info. Still haven't put the machine in shop,other projects take up the room. Below 0 tonight so heated space is a premium.
I do agree with you about the 331 being sloppy from the factory compared to some other brands.looking forward to getting it repaired. thanks
 
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