Bobcat T190

rodneyp10 · Feb 17, 2014

Bought a used machine. Description was trans failure, won't move.
Hauled home and began testing.
It had a low charge pressure fault, cold oil about 1000 RPM's had 325 psi.
If I read the manual correctly, the charge pressure is regulated in the drive pump, down between the engine and pump. I pull the relief and the plunger is stuck on the valve pin, fretted or worn. I disassembled and polished up so seat moved freely on stem. I also added a shim when I reinstalled, I did not reinstall a gauge, light is still on. It intermittently logs a 15-4, charge pressure excessively low. Not every time.
I am thinking I need a drive pump and a pair of wheel motors.
Anybody know of anything I might be missing?

CM1995 · Feb 17, 2014

Welcome to the Forums rodneyp10! :drinkup

Unfortunately I am of no help for you when it comes to the deep internal workings but we are fortunate to have a resident Bobcat expert Wille and he'll be along shorty to help you out.

willie59 · Feb 17, 2014

rodneyp10 said:
I am thinking I need a drive pump and a pair of wheel motors.

Unless you have really deep pockets, that ain't a thinking thing, that's a chunk of money. :yup

Go back to diagnosing. First of all, just to verify, are you removing the charge pressure sensor at the hydraulic filter housing and connecting your pressure gauge at that port? Second, charge pressure should be 240-260 PSI at high idle and oil at operating temp (140F +/-), 325 PSI is incorrect, remove shims at pressure regulator and get back in spec. Lastly, have a hyd hose shop make you a length of hose so you can connect a pressure gauge and run it to operators cab with gauge, operate the machine and monitor charge pressure, if it remains in spec, and machine operates proper, that charge pressure sensor has been lying to you with the excessive low charge pressure code.

rodneyp10 · Feb 18, 2014

There are no functions on the machine. The bucket will try to roll, about one inch of stroke on the cylinder. The left track will just move, like the brake is on. I resealed the right brake, so with no hydraulic pressure, I suspect the brake has not had enough pressure to start to release.
Yes the sensor port is where I checked pressure. It originally had a 15-5 fault, I replaced the sensor and now have an intermittant 15-4.
It starts, turns on the buzzer and charge pressure light and shuts down. It will run 30 seconds more at high idle rather than idle, but never more than 2 minutes.
My assumption was charge pressure excited a port or valve to allow the functions of the rest of the machine. I assumed I was loosing charge pressure in the drive pump and not allowing other functions.
I will get a hose made up to monitor pressure in the cab. I suppose a tee would be good, so the sensor can be installed also.

willie59 · Feb 18, 2014

Maybe I read your first post incorrectly, I thought you were saying you had 325 psi of charge pressure?

What's your machine serial number?

Is it a high flow machine?

Is it standard controls, AHC, or selectable joystick control?

rodneyp10 · Feb 19, 2014

Correct, at high idle it does have 325 PSI and sets a 15-4 fault.
531613295
The control panel on the upper right has a switch that changes the flow, not sure exactly what it says, rocker switch that changes. Not at the machine right now to verify?
The control levers attach directly to the drive pump with flat rods. There are electrical switches on the control, they are not pilot operated joy sticks. I believe standard controls.

willie59 · Feb 19, 2014

Hmm, I'm puzzled, if you're getting 325 psi charge pressure, you should not be getting codes for low charge pressure as it's actually higher than it's supposed to be at 245 - 255 psi. It sounds like one of the auxiliary hydraulic valves is partially engaged, but I'm not certain about that. I'll check out that theory at work tomorrow.

frogfarmer · Feb 20, 2014

I realize if it has 325psi of charge pressure the drive belt must be working but I cant help but wonder if the belt has been checked.

willie59 · Feb 20, 2014

Good point frogfarmer, it's possible the belt could provide enough power to develop charge pressure with no functions being operated, but once you operate a function putting load on belt it could slip and everything go dead. It's worth looking into.

rodneyp10 · Feb 21, 2014

I will check that tomorrow and let you know. Thanks

rodneyp10 · Feb 22, 2014

Ok, checked belt and its tight and the pump continues to rotate.
I them disconnected the steel pilot pressure line from the outlet of the filter that feeds the valve bank. I attached a gauge to that port, so now the lift section and valve bank are disconnected, 310 PSI until I pull a track lever, pressure goes to zero.
Now I am thinking I am loosing pressure in the hystat pump. I am thinking I bypassed the rest of the machine.
Now I remove the number 12 line that comes out of the filter that goes to the hystat pump. I machine a 1/8" orfice and place in hose. I reattach the hose, now I have a restricted line to hystat, thinking I have additional pilot pressure. I lost my gauge port so I can't monitor pressure, still no loader function. I really would like a flow gauge at this point, although I am having difficulity believing the gear charge pump has failed.

I attempted to attach a picture. I don't believe it attached.

crewchief888 · Feb 22, 2014

the main )loader) hyd pump and charge pump are seperate pumps.
on the k series machine you have they are piggybacked together on the right end of the hydrostat.

and seeing that this is a rental unit from sunbelt, i'd be almost positive that the gear pumps are damaged.
most rental houses dump equipment when it's broken/damaged and out of warranty

wouldnt be the 1st set of (gear) pumps i've seen that are crapped out

:drinkup

rodneyp10 · Feb 22, 2014

So does crapped out mean pumps and motors or just the pump?
If the pump failed and sent debris to the motors, they are most likely junk also, correct?

rodneyp10 · Feb 22, 2014

Hey Crewchief;

I just read your note again, and it said gear pumps. What is the failure in a gear pump? My experience with gear pumps is they are durable?

willie59 · Feb 22, 2014

The oil goes through the hydraulic filter before it goes to the drive pumps.

crewchief888 · Feb 23, 2014

on the gear pump failures i've seen, one or more of the shaft bushings have siezed and spun in the pump housing.
also seen the splined coupler between the 2 pumps broken,and stripped the splines on the shafts.

my conclusion was at some time (recently, typically within 100 hrs or so) the machine had blown a hose, hyd system had been run dry, causing the damage.

pull both filters, and dump them into a clean container and check for debris. metal pieces are from the hyd and charge pumps, if you find brass, thats from the valve plates in the hydrostats.

:drinkup

rodneyp10 · Feb 23, 2014

Crewchief, I do believe you are correct. Both pump sections show where they have failed. When I first disassembled the pump I looked at the brass plates and they were not chewed to bad. When I was washing, I found the damage to the inlet side of both the charge pump and the hydraulic pump.

Hopefully the pictures attached and you can see the damage. Thank you for the assistance.

rodneyp10 · Feb 23, 2014

willie59 · Feb 23, 2014

I'll bet if you look at the bushings where the shafts ride you'll see grooves worn in them from the shafts, that's what causes that scuffing of the gears against the housing.

rodneyp10 · Feb 24, 2014

This is my first hystat so bear with me. If I understand this correctly, the charge oil to the hystat pump is filtered, so no debris should be downstream of the filter. Thus there should be no additional damage to the rest of the system.
My concern is if I replace this pump and have additional damage, if I have to buy a hystat pump, I am then in upside down mode from a cost perspective. Should I be looking for any additional problems before I buy this pump?

Bobcat T190

Active Member

Administrator

Administrator

Active Member

Administrator

Active Member

Administrator

Well-Known Member

Administrator

Active Member

Active Member

Senior Member

Active Member

Active Member

Administrator

Senior Member

Active Member

Active Member

Administrator

Active Member