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Repairing creeping Bobcat

Discussion in 'Skid Steers' started by willie59, Aug 29, 2010.

  1. willie59

    willie59 Super Moderator

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    Well, time for another Bobcat thread.

    Ok, I'm seeing way too much of this on Bobcat machines lately, Bobcat has changed a component on the drive neutral centering device, they must be using some cheap steel or something. You don't typically see this on the older BC machines, I've got a 753 in the shop right now that looks like the original components and they don't have the wear the newer machine components have. What am I talking about? Let me get the centering plate off and you'll see it.

    T190 drive neutral plate 001.jpg

    Caution; before you make any repairs or adjustments to the drive centering device on a Bobcat, the first thing you must do is get the machine off the ground on 4 stands. Don't trust just tilting the bucket forward and lifting front wheels, it could drift down. It must be on stands or sturdy blocks.

    First, you have to remove the centering spring. Now, there's a little trick to this. You can remove it quite easily. But then putting it back on is a bit of a problem because you have to compress the spring to start the nut on the long center bolt, you only have two hands and no room for a helper in there.

    Here's a solution that works well for me. Thread a good quality zip tie under spring, at least two (three is even more durable) zips.

    T190 drive neutral plate 002.jpg

    Move one of the drive levers just slightly off center to compress spring just a little, then zip the ties.

    T190 drive neutral plate 003.jpg

    Now you can remove the center bolt/nut, and you have a handy caged spring that's ready for re-install.

    T190 drive neutral plate 004.jpg

    T190 drive neutral plate 007.jpg

    continued...
     
    Last edited: Aug 22, 2017
  2. willie59

    willie59 Super Moderator

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    Once the centering spring is removed, you just simply lift the centering plate off and you'll see the pintle arms that control the pump shafts. Now you can see the problem, the wear on those two centering spools bolted on the pintle arms. I'm seeing these worn spools more and more on newer model machines. We own an S185 that's just a little over a year old, about 800 hrs on it, and these spools have been replaced twice. Once this wear occurs, the pintle arm isn't being held in neutral position and will cause the machine to creep.

    T190 drive neutral plate 005.jpg

    The spools have a 3/8" hex key hole in the top of them, and are fastened to the pintle arms by a hex head bolt from underneath. And there's not enough room to get even a short socket under the pintle arm to grab head of bolt. Additionally, the bolt head is in a recess, can't even grip enough of the bolt head with the open end of a wrench. More brilliant Bobcat design.

    T190 drive neutral plate 008.jpg

    I have a 9/16" S-K wrench that has just enough protrusion on box end of wrench to grip just enough of the bolt head to pop spool loose with allen head socket on spool. All you have to do is break the spool loose, give it a half turn to clean metal, and lock it down. But I remove the spool and install a split ring lock washer on the bolt for a spacer, that makes getting a hold of the bolt head much easier. Here's one of thespools and bolt.

    T190 drive neutral plate 006.jpg

    Turn both spools on the two pintle arms around to fresh metal. And while your in there, be sure and check the bolt that locks pintle arm to pump shaft, that bolt needs to be tight.

    T190 drive neutral plate 011.jpg

    The steel bars bolted to the centering plate are going to be worn as well, simply remove the fastening bolts of the bars, flip the bars around, and bolt them back on. The bolt holes on right bar are round, the holes for the left bar are slotted. Lock down the bolts in the right bar, but leave the ones in the slotted holes for left bar loose to make adjustment.

    T190 drive neutral plate 012.jpg

    continued...
     
    Last edited: Aug 29, 2010
  3. willie59

    willie59 Super Moderator

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    Here's the left pintle arm with the spools turned around. Notice the two 3/8" bolts that fasten the pintle arm to the pump control arm. The bolt that's in between the two spools goes through a round hole and screws into the pump control shaft. The bolt to the right of spools goes through a slotted hole and fastens to the end of pump control arm. This is how drive centering adjustment is done using the allen head screw on front of pintle arm. We'll go over that in a few minutes.

    T190 drive neutral plate 015.jpg

    Now we have spools and bars flipped around, simply fit the centering plate in place, and re-install that handily caged centering spring.

    T190 drive neutral plate 016.jpg

    The centering bar to the right is set because we locked the bolts down on it. Now we need to set the left centering bar. Make sure the left pintle arm is in centerline with right pintle arm as best you can as it will move fore and aft. Just slightly set bolts for left centering bar in slotted holes.

    T190 drive neutral plate 017.jpg

    Tap the side of the bolt heads to move centering bar toward spools until it contacts spools. Give the bolt heads a bit more lock down.

    T190 drive neutral plate 018.jpg

    Grasp the machine right side drive lever that you use to drive the machine and move it gently fwd and rev, checking for any movement of the pintle arm. There should be no looseness of the pintle arm spools contacting the centering bars. If there is, loosen front bolt, move the drive operating lever slightly in reverse direction, and tap the front centering bar bolt with hammer to move it closer to the spool on pintle arm, lock bolt again. If you adjust too far, you will cause looseness of opposite centering bar on right side of centering plate, the side with holes that don't adjust. Once you get no looseness of either drive lever, firmly lock down bolts for centering bars and re-check that nothing moved during torquing bolts.

    T190 drive neutral plate 019.jpg

    continued...
     
    Last edited: Aug 29, 2010
  4. willie59

    willie59 Super Moderator

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    Now, let the cab down, plant yourself in the seat, and start the machine. It may try and move one of the drives because final ajustment is yet to be done. You may have to hold one or both of the levers pushed or pulled slightly to neutral the pumps until you get the engine running and brake lock released. This is why you have to have machine on stands or blocks. Once you get it running and brake lock released, raise the cab back up. You'll more than likely have at least one side, or both sides, creeping a bit. To adjust and get drive neutral, slightly loosen bolt in pump shaft.

    T190 drive neutral plate 020.jpg

    Loosen bolt in pump control arm in slotted hole.

    T190 drive neutral plate 021.jpg

    Turn the adjusting screw CCW (screwing out) until that side creeps in reverse. Slightly tension the two bolts.

    T190 drive neutral plate 022.jpg

    Crank the adjusting screw CW (screwing in) with allen wrench until that drive finds neutral. Lock down bolts. Some movement may occur during lock down, you may have to tweak a bit more.

    T190 drive neutral plate 023.jpg

    If you adjust too far and get forward creep, you have to regroup and do it over again. Once you get neutral on both drives your good to go. On older machines that have aluminum pintle arms, the adjusting procedure is a bit different. I should be repairing the drive centering on the 753 with aluminum arms this coming week, hopefully will be able to follow up on those repairs at this thread.
     
    Last edited: Aug 29, 2010
  5. m630

    m630 Active Member

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    looks like fun lol
     
  6. frogfarmer

    frogfarmer Well-Known Member

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    This is a simple adjustment operators should insist be done. There is no substitute for safety.
     
  7. willie59

    willie59 Super Moderator

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    Now a little info about the older machines with aluminum pintle arms. Got in the cab of the 753 customer had dropped off and it was all over the place. I knew immediately that the clamping bolt for the right drive pintle arm had come loose. Well, here's the belly of the beast. Pretty much the same thing as on the T190, cage the centering spring with cable ties, remove centering spring, then lift neutral centering plate off. On this model, more difficult to get to the centering spring, had hoses and stuff in the way. Grrrrrr.

    Bobcat 753 drive neutral plate 001.jpg

    Centering plate removed, the pintle arm on the left is the one the clamping bolt that holds arm tight on pump shaft came loose allowing pintle arm to wallow all over and couldn't control pump shaft movement. These machines drive nutty when they come loose. Notice the difference in the spools on the aluminum arm models as opposed to the spools that wear on the T190 mentioned earlier. These spools actually look like a chromed steel.

    Bobcat 753 drive neutral plate 002.jpg

    Minimal wear on spools as well as centering bars.

    Bobcat 753 drive neutral plate 003.jpg

    Bobcat 753 drive neutral plate 004.jpg

    Two new pintle arms. One from being worn by loose clamping bolt, other had excessive wear where rubber torsion bushing goes. Install new torsion bushings, installed old but still good spools on new arms, rotated them around to fresh steel, and rotated centering bars on centering plate.

    Bobcat 753 drive neutral plate 005.jpg

    I should offer an installation note whenever perfoming repairs to Bobcat drive linkages. Whenever you remove the bolt that attaches drive link to pintle arm via the rubber torsion bushing, when you go to re-install the torsion bushing bolt you must have the pintle arm near the neutral position. Once the bolt is tight, moving the machine drive lever fwd and rev actually twists the rubber of the torsion bushing. Point is, if you had the machine drive lever and pintle arm all the way forward and installed the torsion bushing bolt and locked it down, then when you pulled back the drive lever, it would simply try to go back foward like a spring was pulling it. That's from twisting the rubber of torsion bushing. Always have pintle arms in line with each other when installing torsion bushing bolts.

    continued...
     
    Last edited: Sep 3, 2010
  8. willie59

    willie59 Super Moderator

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    Now the main difference between the aluminum arms and two piece steel pintle arm, there's no centering adjusting screw like on the steel arms. The drive centering adjustments are done solely on the centering plate. Notice the holes on the centering plate that mount the centering bars. The holes on the left (for right side drive) are both slotted. The holes on the right (left drive) has one hole slotted and one plain round hole. That's where adjusting begins, the round hole is the pivot point and the slotted hole is the adjusting point for left side drive. Mount the centering bar to the plate with round hole bolt, then mount opposite end bolt in the mid point of slotted hole, lighty lock down bolts. Install opposite centering bar with two slotted holes, push bar away from other centering bar and lightly lock bolts.

    Bobcat 753 drive neutral plate 006.jpg

    Fit centering plate onto guide pins, re-install centering spring. Now we can start adjusting. Again, you must have machine on stands or sturdy blocks, wheels off ground. Start machine and release parking brake lock. Adjust left side drive first. If there's no creep of left drive wheels, lock down the bolts for that centering bar. If there is creep of left drive, put a little light torque on round hole pivot bolt.

    Bobcat 753 drive neutral plate 007.jpg

    Have a little tension on the slotted hole bolt. Move left side drive lever to reverse drive to seperate spool from the centering bar at that bolt, tap the side of the head of the slotted hole bolt in the direction needed to achieve neutral. Once neutral is achieved, start torquing the bolts, keep moving drive lever in fwd and rev while torquing and checking that neutral is good. Once you get neutral, lock bolts tight.

    Bobcat 753 drive neutral plate 008.jpg

    Now that you have the left side drive set and not creeping, it's time to adjust the right side drive. Since they are all the way left in there slots, there's going to be considerable movement of the machine drive lever. With the right machine drive lever holding the right wheels in neutral position, or close as you can, loosen the bolts in the centering bar and move it to the right in the slotted holes until centering bar is against the spools of pintle lever, lightly torque bolts. Adjust the two bolts to achieve drive neutral for right side drive, making sure the centering bar is contacting the spools, you can't have any slack between bar and spool contact or it will creep, but you have to make sure the adjustments on that side don't cause slack for the opposite side drive. Once you get right side drive neutral, lock bolts down tight. Move both drive levers in fwd and rev and make sure there is no drive creep.

    Bobcat 753 drive neutral plate 009.jpg
     
    Last edited: Sep 3, 2010
    WRB1717 likes this.
  9. bull

    bull Active Member

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    Excellent tutorial. Thanks ATCO!
     
  10. 90xtskid

    90xtskid Member

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    creeping bobcat

    Very well detailed reply with pictures-I like it.:)
     
  11. pcbobcat

    pcbobcat New Member

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    ziptie!

    thanks so much for that trick.
     
  12. willie59

    willie59 Super Moderator

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    I'm kinda hoping this info will help some machine owner do his own repairs instead of unloading the wallet to pay the big shop to do them. :)
     
    J-mac likes this.
  13. jean

    jean Member

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    this is my third reply. Yeh! and i hope that when i finally get to ask a question this guy is around to give me an answer.
     
  14. willie59

    willie59 Super Moderator

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    OMG...I hope I am too! LoL :D

    Welcome to the forum jean. :usa
     
  15. usediron

    usediron New Member

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    863 creep adjustment

    Is the adjustment procedure basicly the same on the 773 and 863's. I have a 863 1999 vintage.

    thanks
     
  16. willie59

    willie59 Super Moderator

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    Your machine should have the same components. Being a '99, I'd say you have the aluminum pintle arms. :)

    BTW, welcome to the forum usediron. :usa
     
  17. mrfixitpaul

    mrfixitpaul Well-Known Member

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    Not sure what years, but some of the older 863's used cables to control servo spools in the pumps, instead of manual linkages......way different procedure for adjustment.
     
  18. willie59

    willie59 Super Moderator

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    Yeah, been a while since I've seen one of those cable jobs, I would think by '99 it would use the link system. Not certain about that myself. :)
     
  19. punchlist

    punchlist Member

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    Would this fix work on a t180 that one track is going faster than the other?
     
  20. willie59

    willie59 Super Moderator

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    Welcome to the forum punchlist. :usa

    You mean one track faster than the other, like, when you have the drive levers all the way forward, one tracks is faster than the other, making the machine turn?