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CASE 850 - Transmission Control Valve/Braking/Steering issues

Discussion in 'Track Loaders' started by cyberbiker0, May 23, 2015.

  1. cyberbiker0

    cyberbiker0 Member

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    Hey folks,

    This '74 Case 850 is almost impossible to steer using the brake pedals. It does somewhat ok on an upgrade, it becomes harder to brake on level ground, but when traveling in reverse on a downgrade it takes all my might to disengage the tracks (thus no turning or braking) ability. The following photo is its Transmission Control Valve (TCV)

    control valve.JPG

    We have all new seals that goes in the TCV, fairly new master cylinders & slave cylinders. We have bled out all the air in the brake lines. The slave cylinders & brake levers does operate with the brake pedal. I removed the back plate (#2) on the TCV & the brake spools (#10) do function with the brake pedals. All the mechanical(s) check-out.

    My 5,000 page service manual states "Check to see if the spools fit their respective bores with a slight hand pressure & w/o excessive side clearance". That is not a very scientific description! They should have included wear limits in this manual - especially when it comes to brakes.

    Does any1 know how much is too much?
    The min spool diameter?
    The max bore diameter?
    Can just enough fluid pass through worn spools to make the drive train clutches only partially disengage? such as clutch slippage.
    What else can cause the tracks to keep driving when the brakes are depressed?
     
  2. DMiller

    DMiller Senior Member

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    May be mistaken but the last 850 I got on had hand levers for the clutches and brakes were only used to make sharper turn after the lever was already pulled?
     
  3. cyberbiker0

    cyberbiker0 Member

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    This uses high-low levers connected to the TCV and those various spool positions (#4) sends hydraulic fluid through various lines, which pressurizes clutches in its transmission case. when the brakes are pushed, the 2 lower spools (#10) cut-off all fluid to the trans. thereby neutralizing the drive train as the brakes are applied. it sounds like the same operation & i use the high-low levers for wide turns. the brakes for sharp 90's, 180's, etc.

    i hear the brakes & drive train are becoming a bit more cooperative, so maybe the new seals just needed a little break-in period. still, the service manual should have been more specific. i just don't want to spend $200 on 2 spools & still not be fixed.
     
  4. Dickjr.

    Dickjr. Senior Member

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    The 850's we had would disengage the track when the brake pedal was pushed ,and the farther down you pushed the pedal the brake would start to engage. It took a decent amount of effort to lock the track. Your legs would be tired at the end of the day for sure. If it has the trans pressure gauge , it should fall back when the pedal is pushed. Your actual brakes could be worn causing it to take more effort to turn. The E models and up had hydraulic assist which worked better.
     
  5. cyberbiker0

    cyberbiker0 Member

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    that is exactly what we are having to contend with Dickjr :cool: the brake-spools (part #10 (above)) disengages the drive train on this 1974 Case 850 .....and it does take a tremendous amount of leg power to stop the track. i just thought something was malfunctioning to make it that hard to brake-steer. the brake disks might be worn (or wearing) out too, because the slave cylinder adjustment bolts (part # 32 (below)) are almost fully screwed in. i dread messing with that :( but if it will make it easier to use then it'll be well worth it :usa Thanks for the advice Dickjr

    Case brake assembly.jpg
     
  6. Dickjr.

    Dickjr. Senior Member

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    Looks like the brakes are dry type? If so they more than likely need relining and cleaning real well. The actuators need to be cleaned and checked for wear in the moving parts that could cause binding.
     
  7. cyberbiker0

    cyberbiker0 Member

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    It's true that they are dry brakes & it never occurred to me that they might be binding up - making it harder to use. For some odd reason 1 of the former owners welded the brake actuating shaft (30) to the brake lever (34) ..so we may not be able to disassemble it, or possibly grind it apart.

    I just want to use this machine some day instead of perpetually working on it, but we're getting there.
     
  8. sheepfoot

    sheepfoot Senior Member

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    In your first pick idem 21 is what pushes the brake cutout spool that dumps the pressure to the track depending on which pedal is pushed. The brake system did not last long on those machines, they glazed over or crud would get in the vane's in the disc, oil leaks inside the housings and you could not put enough force on the pedal to stop the machine. I kind of think you think it's still pulling but the truth may be they are glazed or oil soaked. We would take a rat tail file and cut the groves on the disc's to let the crud out. Those are the same type disc used in many of the older farm tractors and you could ruff them up/sand blast/bead blast them and they would run for a little longer but would fail again down the road. This is why they went to wet brakes to solve that problem on later C/D machines.
     
  9. cyberbiker0

    cyberbiker0 Member

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    Every1 was right. The spools are disengaging with brakes. It is the brakes that are dysfunctional. I found this out the dangerous way :eek: as I was on a slope, the machine got a bit out of control, so I hit 1 of the 2 brake pedals. That track sped up (instead of stopping) while the other track maintained speed & launched me into the ditch & into sapling trees!!! i nearly needed a change of underwear. Out of habit (and panic) I managed to make that error a 2nd time & lived to tell about it. Fortunately, that is the worst part of the driveway & it is nearly done. I hope I survive it!!!

    Anyways, I just wanted to express my many thanks for coaching me through this restoration process. Y'all are grrrrr8 people :usa
     
  10. Jackson101

    Jackson101 New Member

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    I'm just starting in on my 1974 850 Bulldozer. The undercarriage is a wreck and "shocker", the brakes don't work!!
     
  11. frankieavalanche

    frankieavalanche Member

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    Location:
    canada
    I have reading posts for awhile now to help me restore an old 750 case track loader.I have completely rebuilt everything except the engine The brakes and hardware Pedals master cylinders and brake housings have been removed a long time ago .After reading anything i could find on the internet most people who operate these machines say the brakes were the first thing to go and are not worth fixing.I have been restoring a few years now and hope to get it moving this winter . My question is is it possible to put line locks or something on the control tower to give me some kind of brake or parking brake as the land have has some hills i need to put roads on.
     
  12. wosama931b

    wosama931b Senior Member

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    If it has old brake pads , you could remove the old liner, and make up new ones and rivet the liner back on . sam .
     
  13. frankieavalanche

    frankieavalanche Member

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    Thanks for replying Sam
    the brake housings and everything was removed i was just wondering if i could do something on the control tower
     
  14. sheepfoot

    sheepfoot Senior Member

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    frankieavalanche, the brake discs stop the pinion shaft from turning, that is the reason the cutout has to drop the pressure so your not driving threw them while driving and trying to stop and or turn. The discs hold with the parking brake applied to the pinion shaft, which causes the ring gear/ bull gear /axle shaft /sprocket / track not to turn. Their is nothing you can do with the control valve to change this set up.
     
  15. frankieavalanche

    frankieavalanche Member

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    Thank you sheepfoot. I certainly will have to get used to the machine.The brake system was removed a long time ago according to previous owners.I did see a link awhile ago where a guy added levers to the control valves . I think what he was doing was making it easier to turn buy disengaging one side at a time for quicker turns, or both sides to make it less harsh on the transmission shifting from forward to reverse. I agree there is nothing else i could do to change the setup to have brakes.
     
  16. DMiller

    DMiller Senior Member

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    First item returned to function on my Allis was the brakes, I live in hill country and appreciate being able to stop or park my machine and be comfortable it will do so when needed.
     
  17. frankieavalanche

    frankieavalanche Member

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    well i finally got to running the 750 track loader . Getting along fine with no brakes . I am trying to get the generator to work .Its 24 volt positive ground Delco Remy no. 1105228. I am keeping it that way . I purchased new parts for the generator. (Bearings brushes&field coils). The field coils i took out have three wires, the new field coils only have 2 wires.I added a wire in between the two field coils.This is were the third wire was on the original field coils and wired them the same way but i still can not get the generator to work. I have polarized it every time i put it back on the machine. Any help would be appreciated.
     
  18. Alex1617

    Alex1617 New Member

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    Ok
    I have a 750k dozer 04 model I was having problems with it not moving forward or back I got the right track to move but the right side try’s to move but just moves about inch and stops do y’all think it might be the break and the break pedal is real soft
     
  19. DMiller

    DMiller Senior Member

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    Have you replaced the regulator for the generator, cannot remember a 750 with a generator these most often had Pos Grd Alternators.
     
    Ronsii likes this.
  20. frankieavalanche

    frankieavalanche Member

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    Hi DMiller
    My Generater rebuild was good .After running the machine for a while the starter went out
    The guy that rebuilt the Starter suggested changing to negative ground and showing me how easy it was i gave it a try and lo and behold the generater started charging.
    I have run the machine quite a bit now .It works awesome.
    The only trouble i had was i got very comfortable operating and started using high gear. Well i was on my hilliy drive way in high gear backing up grading with the bucket down and she stalled.I went for a ride on the side of the driveway into the ditch. I did not get hurt but it was a good lesson not to get too cocky
     
    DMiller likes this.