PT1445 20 hrs, Lost steering!

[J_J]

A low hydraulic oil alarm (loud) or automatic shutdown would be ideal. It wouldn't be terribly hard or expensive to do, if Power Trac built it in in the first place. Since they didn't, it would require the hassle of cutting into the tank to mount the float switch, not to mention the research required to find just the right switch and mounting method for the job.

Out of curiosity, does other hydraulic drive equipment typically come with something to prevent damage from or warn of the loss of hydraulic fluid?

Snowridge,

How about this bit of logic. Why not have the suction for the most critical pump close to the bottom of the tank, and the other pumps by order of priority. Three levels of fluid draw. Of course an alarm for low hyd fluid would be advantageous, and could easily be implemented. I believe that some of the skid steers have a hydro warning light.

 

[woodlandfarms]

I would not want a pressure warning light. Kill switch, but not a warning light. Given the pumps, I think it would be too late if the light said you are out of pressure. By the time you kill the engine....

Also, I don't know how my tank is designed. Is the bottom open all the way across? If so, you would need two oil sensor cause of slope work. one on each side of the tank..

Thoughts?

 

[J_J]

Carl,

There are many reasons why an engine would shut down. You would have to have a light to tell you which switch had activated. The pressure switches might be a problem anyway, because the pressure varies in the systems. You don't always have 3000 psi. A gage or light would tell you when the hyd fluid is low. With all the digital stuff, they could theoretically monitor just about everything that moves, has temperature, or air, etc.

If I remember right, some of the engines will not even start with a hydro warning light on. That simply tells you to check the fluid.

 

[Bob999]

Out of curiosity, does other hydraulic drive equipment typically come with something to prevent damage from or warn of the loss of hydraulic fluid?

I have a Bobcat A-300. Instrumentation includes a monitor on the hydrostatic charge pressure with notifications for low pressure, pressure out of range, and hydraulic charge pressure very low - engine will shut down in 10 seconds. There is also instrumentation on the hydraulic oil temperature (high) and on the hydraulic oil filter (restriction) with in-cab warnings of out of spec conditions.

 

[SpringHollow]

Also, I don't know how my tank is designed. Is the bottom open all the way across? If so, you would need two oil sensor cause of slope work. one on each side of the tank..

Thoughts?

My recollection from cleaning it is that it is connected.

Ken


Edited: Checked my pictures at home. There is a gap underneath the pass through tunnel. See attached image.

 

[ponytug]

Dear PT1445farmer,

I have another thought on why your tank might be empty; if the return line was open from the steering assembly, could it have siphoned out the contents of tank, after you turned the engine off? Whatever the reason, I hope that no damage was done to the pumps or the tractor.

On a side note about the bobcat:
Wow! A hydraulic charge pump very low engine kill switch. It sounds so simple, so valuable, and so much effort to engineer in after the fact. But valuable enough that it might be worth trying to do.

One upside to having lots of machines in the field is that the design evolves to reduce common failure modes.

Given the slopes that these machines operate on, you might need to have the level sensor in the center of the tank to avoid misreads as slopes are traversed/climbed/driven down...

One thing that is attractive to me about the charge pressure monitor is that would also catch plugged intake filters.

All the best,

Peter

 

[J_J]

Ponytug,

You maybe right about the charge pump, but does the charge pump always have pressure, or does it build pressure when it needs to replenish the closed loop system? The pressure is in the area of 300 psi. I believe that all PT's have a place to test the charge pump pressure, and that would be a good place to put the switch/light. A good filter housing filter assembly should have a gage on it to read pressure or time to replace indicator.

 

[SnowRidge]

Ponytug,

You maybe right about the charge pump, but does the charge pump always have pressure, or does it build pressure when it needs to replenish the closed loop system? The pressure is in the area of 300 psi. I believe that all PT's have a place to test the charge pump pressure, and that would be a good place to put the switch/light. A good filter housing filter assembly should have a gage on it to read pressure or time to replace indicator.

It's probably different with every model (of tram pump) out there. Mine jumps up to 7-800 PSI with the implement option (not used by PT), otherwise it runs much lower. While a warning going off on loss of charge pressure would be better than nothing, I still think the best thing would be a low oil level alarm for the tank.

There is no reason it has to be rigged so the tank is almost empty. It would be just as easy to set it up so that it alarmed when the tank dropped to 90%. That would give the operator time to react and shut down before the tank was emptied by whatever failed.

 

[MossRoad]

There is no reason it has to be rigged so the tank is almost empty. It would be just as easy to set it up so that it alarmed when the tank dropped to 90%. That would give the operator time to react and shut down before the tank was emptied by whatever failed.

That seems like a good idea. How would you rig it up? Some kind of limited float mounted through the access plate on top of the tank? Anyone got any links to components that could be used?

 

[J_J]

That seems like a good idea. How would you rig it up? Some kind of limited float mounted through the access plate on top of the tank? Anyone got any links to components that could be used?

David,

I had a gas cap which had a float and indicator which gave you the quantity of the fuel in the tank. What it amounted to was a spiral shaft with a float that slid up and down to indicate fuel level. The same principle could be applied here. A float that can handle hyd fluid. A spiral shaft, that is equivalent to the depth of the tank, that will give one full turn from empty to full. This can be determined by the number of turns on the shaft. otherwise, when the float is at the bottom, then the indicator would read empty or low, and when the float was at the top of the full level, the indicator would read full. This could also be done electronically, by using something like the lever float in a regular gas tank, empty to full. You would think someone would have done this by now. That gives some of you technicians out there an in site to come up with some something that could be adjusted for the level of different tanks.