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Bobcat T190 Park Brake

usmcmurillo20

Member
Joined
Sep 29, 2015
Messages
16
Location
Altoona
Occupation
Mechanic
Hey guys I am new to this forum and from what I've seen looks like a very good one I hope to help out anyone I can in the future and hope someone could help me out. Have a T190 sn 531615935, with pedal controls also. I can't get the park brake to work. Fuses and relays are good. Has no codes. Has new switch. Switched out ecu by your left thigh on frame. and the touch pad in the upper left corner. The machine is not a deluxe. Thought maybe charge pressure was an issue but bobcat said for my machine its 360psi high idle and that's what it has. Checked it at the control valve and have 290psi. Anyway you can get into the machine with the seat bar up cab up and all. Start the machine and right away be able to move it. Seat bar doesn't matter and you don't have to press the green operate button. Seat bar works as it should for the bucket lift and tilt. So its as if it is in free wheeling mode it will just roll on an incline. checked to see if the case strain filters from the drive motors were clogged up and putting back pressure on the motors and it wasn't. Had a little metal debris but other than that it was fine. Machine runs and operates great but has no park brake. Checked coil on stem valve on the service brake valve and it has 5v no mater if the switch to the park brake is on or not. Not sure what its supposed to read with it on or off. I took that coil and valve off and put 12v of power and it works just fine. I think maybe it has to be bypassing somewhere. You hear a lot of people having trouble getting the brakes off of these machines and here I am trying to get them on haha. With my gauge on the standby pressure port (removed charge pressure sensor) when I turn the brakes on pressure drops about 20psi for a second then goes back up. Each time you flip the switch. Only thing I can think of is maybe its bleeding passed the valve some how. If anyone can help please do thanks for your time. Ive been working on this thing for a little while now an part of the reason it takes so long to is I don't have access to hydraulic schematics and electrical schematics. :pointhead
 

willie59

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Dec 21, 2008
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Knoxville TN
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If I'm reading you post correctly, the parking brake is released with lap bar either up or down and you don't have to push the "operate loader" button as well, no? About the only two things I can think that would do that would be broken springs in both drive motors (not likely) or a fault with the brake control valve. I think I'd disconnect the hoses from the brake valve that goes to the right and left motor brake ports, cap/plug the disconnected lines and ports, then start the machine and see if the brakes hold.
 

usmcmurillo20

Member
Joined
Sep 29, 2015
Messages
16
Location
Altoona
Occupation
Mechanic
Yes that's correct willie you can just get in and move it. That's what I was thinking its as if the springs were gone is what its acting like and I thought no way but weirder things have happened. Im going to try what you said about the brake valve. At this point I want to try anything to trick the machine in putting the brake on just to be sure it will. Thanks.
 

usmcmurillo20

Member
Joined
Sep 29, 2015
Messages
16
Location
Altoona
Occupation
Mechanic
Well its the last thing I thought broken springs, I conducted that test and machine still moves freely even after taking off the lines. They aren't engaging. Thanks for all the help again willie
 

crewchief888

Senior Member
Joined
Feb 1, 2012
Messages
1,781
Location
NWI
never seen/heard of the brake NOT engaging...

ive never seen a broken brake spring in a t190...


single speed or 2 speed machine?

any insight on previous repairs?
or was the brake working and just started doing this?

:confused:

:beatsme


:drinkup
 

willie59

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Dec 21, 2008
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Knoxville TN
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Service Manager
never seen/heard of the brake NOT engaging...

ive never seen a broken brake spring in a t190...

Agreed, and I've never seen failed brakes or brake springs on both drive motors at the same time. Something unusual going on here. :beatsme
 

usmcmurillo20

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Joined
Sep 29, 2015
Messages
16
Location
Altoona
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Mechanic
Crew chief this machine is from auction so I would think anything is possible. But I did the test that Willie said to do and with no pressure going to the brake side to release the brakes it still moves as if the manual override is on. It's off though. Seems to be working fine the light comes on when you use it and back off. Would there be a valve that activates manual override and could be stuck? Other than that it has to be the brakes. Only thing I can think of.
 

crewchief888

Senior Member
Joined
Feb 1, 2012
Messages
1,781
Location
NWI
I dunno if it's possible but could somebody assemble the motors minus brakes maybe..?

with an auction machine, anything is possible.....

i'm running "scenarios" through my head as to what could be missing from the brake..

only thing that makes sense right now is maybe they left out a few brake disks....

:idea


:drinkup
 

Nige

Senior Member
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Jun 22, 2011
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28,984
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G..G..G..Granville.........!! Fetch your cloth.
only thing that makes sense right now is maybe they left out a few brake disks....
I've seen that before on a machine from another manufacturer where the park brake wouldn't hold. After a load of hair-tearing both brake packs were torn down to discover that the brake stack was exactly 1 friction disc & 1 plate short ........ Ooooops ........
 

crewchief888

Senior Member
Joined
Feb 1, 2012
Messages
1,781
Location
NWI
Crew chief this machine is from auction so I would think anything is possible. But I did the test that Willie said to do and with no pressure going to the brake side to release the brakes it still moves as if the manual override is on. It's off though. Seems to be working fine the light comes on when you use it and back off. Would there be a valve that activates manual override and could be stuck? Other than that it has to be the brakes. Only thing I can think of.

once the hoses from the brake valve are disconnected, and the valve capped off, theres no oil going to the brake port in the motor...

only other thing that comes to mind, is the drop in charge pressure when the brake is activated...

theres a possibilty that the motor has enough internal leakage that the case drain is pressurizing the brake....

i think i'd disconnect brake hoses again, cap off the brake valve , but leave the hoses open.
start the machine and see if you are getting a lot of oil coming out of the brake hoses...

:beatsme


:drinkup
 

willie59

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I dunno if it's possible but could somebody assemble the motors minus brakes maybe..?

Yes, us old hands at this, you, I, crewchief, we've seen our share of WTF crazy stuff on machines. I once tore down the swing gearbox on a Cat 320C to replace the bull gear seal and found a live .22 Cal round inside the gearbox. How that made sense to anybody still baffles me. In this case, I'm certain the member would like some direction to go with. Like crewchief stated, if you disconnect the brake release pressure hoses from the brake solenoid valve, cap the ports on the valve, and leave the brake release hoses open, you have now blocked any pressure getting to the brake release piston, see if the brakes still don't hold and see if oil is dumping out of the brake release hoses.
 

usmcmurillo20

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Sep 29, 2015
Messages
16
Location
Altoona
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Mechanic
Thanks for all the help and the personal experiences. Well I did that final test there is no leakage in those brake lines I left them completely open started it up and moved the machine. Nothing is bypassing those drive motors. Can't wait to tear it apart and see what is going on. Ill keep you guys posted.
 

apetad

Senior Member
Joined
Jul 24, 2012
Messages
384
Location
Leander, Texas
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Compact Construction Equipment Sales
Yes, us old hands at this, you, I, crewchief, we've seen our share of WTF crazy stuff on machines. I once tore down the swing gearbox on a Cat 320C to replace the bull gear seal and found a live .22 Cal round inside the gearbox. How that made sense to anybody still baffles me. In this case, I'm certain the member would like some direction to go with. Like crewchief stated, if you disconnect the brake release pressure hoses from the brake solenoid valve, cap the ports on the valve, and leave the brake release hoses open, you have now blocked any pressure getting to the brake release piston, see if the brakes still don't hold and see if oil is dumping out of the brake release hoses.
At least they didn't do like the weasel that sold me the 1972 Chrysler, found that a .22 rimfire fits perfectly where the 20amp glass fuse was that overloaded and blew, when the circuit got hot enough BLAM!!! Very nervous thing to have happen when going 70mph down the road!
 

Nige

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Jun 22, 2011
Messages
28,984
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G..G..G..Granville.........!! Fetch your cloth.
At least they didn't do like the weasel that sold me the 1972 Chrysler, found that a .22 rimfire fits perfectly where the 20amp glass fuse was that overloaded and blew, when the circuit got hot enough BLAM!!! Very nervous thing to have happen when going 70mph down the road!
You weren't on a frog-gigging trip at the time were you..?

http://web.ku.edu/~edit/weird2.html
 

Bjones386

Member
Joined
Oct 12, 2015
Messages
8
Location
Florida
My t190 is doing the same thing. No brakes whatsoever. It makes the controls really jerky when turning. When you figure out what is happening with yours, please post back. I'm going to check all of the little things now. Where do I buy the pressure gauges and connections?
 

crewchief888

Senior Member
Joined
Feb 1, 2012
Messages
1,781
Location
NWI
My t190 is doing the same thing. No brakes whatsoever. It makes the controls really jerky when turning. When you figure out what is happening with yours, please post back. I'm going to check all of the little things now. Where do I buy the pressure gauges and connections?

hoses, gauges and fittings are available at hyd supply houses. look for a place that makes hyd hoses.
local napa may have some, (depending on your location)

:drinkup
 

Arnaud

New Member
Joined
Oct 29, 2018
Messages
1
Location
Sospel
Hello everybody,

I have read with big interest all your comments and advices. I am sorry to re-open this conversation of 2015, but, few weeks ago, i bought a compact track loader Bobcat model 864 HF from 2000 and i have exactly the same symptoms as usmcmurillo20 has described at the beginning.
Maybe i didn't get you conclusion and how you have resolved the problem. If somenone will have the kindless to explain me how can i proceed to fix it, please, it would be really nice.
Hope that my American/English is not too bad, sorry in advance for my mistakes but i am writting you from South part of France and as you know French people are not so efficient to speak a foreign language ;-).

Best regards,
Arnaud.
 
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