Auger motor popping hoses

[J_J]

Don't know where your blockage is, but the hyd motor must have free flow to tank.

Do you have a direct path from the motor OUT port to tank?

The EF port is only plugged in a closed center configuration.

If you put a gage in the OUT port, you will know if there is free flow or blocked flow.

The double relief valve is there if you make a mistake in plumbing.

 

[memphismark]

I have direct path to tank, but's it's also tee'd to the EF port per Prince PDF instructions. I can't imagine a blocked, "OUT" port, at the motor because of the blown hoses down stream. There's definitely pressure there, just don't know why so much. Your turn. Mark

 

[J_J]

Let me put it another way.

Does your aux circuit have a return hose and is anything plugged into it?

Do you have a hyd schematic for the machine? Something like this.

 

[SSdoxie]

Does the hose blow during operation, while drum is turning or does it blow when shutting mixer drum off?
What is pressure rating of the hose you are using?

The rerun oil from the motor is NOT going directly to tank. The 753 of this vintage used the return oil from the hydraulic valve to furnish charge pressure to the hydrstatic pump, Oil out of the valve after coming back from the work port goes to oil cooler, through filter, then to hydrostatic pump where there is a 165 psi. relief valve. So back pressure on the return line from auxiliary coupper will always be a minimum 165 psi. If oil was rerouted directly to tank, the hydrosatic pump would starve of oil while running the auxiliary.
Again:
1. What pressure rating hose are you using?
2. Are you running at full throttle? If so run at 1/2 throttle and eliminate the flow control valve.
3. If hose pops only during shut down, idle engine down before shutting off the Auxiliary control.
4. Should have mentioned this as #1, put a guage in the return line from motor and see what pressure it is. It could be something as simple as a blocked/restricted coupler.

 

[memphismark]

Only running at idle, no throttle at all. It's 3500 lb. hose and it blows while mixer is turning and very shortly after it starts turning. Keep in mind that I'm simply plugging two 4 foot hoses with flat faced couplers (1 male, 1 female) into the male/female flat face couplers for the auxiliary hydraulics on the front of the Bobcat. The same place that you would plug in other Bobcat attachments. There is no spool on this side of the auxiliary system. Just whatever attachment you plug into it. I have a backhoe that plugs right in to the two hoses, and the backhoe has it's own spool controls. In the case of the concrete mixer, the other end of the 4 foot auxiliary hoses reach over to the mixer and one line obviously goes to the "IN" side of the Prince RDRS 150-16 flow controller valve, then out from the 'CF' or controlled flow port another short hose goes to the IN port on the motor. There is a 3rd port on the Prince controller that is 'EF' or excess flow. That hose is tee'd into the hose coming from the motor back to tank hose. Hopefully that all makes sense. I had a gauge on the return before and it showed nothing. I assumed it was a cheap Chinese piece which I tossed, but never put one back. I've been away from the project for a few weeks because of the holidays but I'm ready to tackle it again. One thing however, when I took the flow controller off and just ran the auger without it, just straight thru, there was no problem, it's just to fast for a concrete mixer.

 

[SSdoxie]

Mark,
Is there as 3rd, small coupler on your machine? What % of flow (gpm) are you sending to the motor?

 

[J_J]

Then the answer is to run the engine at 1/2 or 1/3 for GPM control.

 

[memphismark]

No, I don't have a 3rd coupler, and I really have no way to know the GPM to the motor. It is supposedly 16 gpm, whether or not that number is meant as full throttle gpm or what I couldn't tell you. Running the auger at just idle seems enough to cause popped hoses. I'm stumped. The auxiliary systems runs the backhoe, log splitter etc. just fine. Your thoughts. Mark

 

[glastron23]

i think you will find a valve down stream of the couplers and when you deactivate the spool to stop the motor from turning the drum, you block the return to tank hose, the drum turning the motor turns it into a pump and builds pressure fast, and with no return to tank,blows the hose. A 4 way cushion valve will prevent this.... Jim
check on page 72, it shows the aux hoses and valve https://www.usedloaderparts.com/wp-content/uploads/2014/08/pdf-bobcat-753g-parts-manual.pdf

 

[memphismark]

I looked at the schematic and there is a control valve downstream as you thought there might be. Help me understand something, bearing in mind I'm a newbie to hydraulics when you answer or keep it real simple I should say. I just assumed to the two lines that make up the auxiliary hydro circuit were one line as a feed, and the other as 'back to tank'. Am I missing something here. I just assumed that connecting one fluid hose to the auxiliary feed at the Bobcat and the other end of the hose would connect to the flow control valve to control the mixer. Fluid would pass thru the valve, drive the motor and the fluid just goes thru the motor and out the other hose to a reservoir, not really under any real pressure. Are you saying that the return doesn't go dump in a nice quiet little reservoir tank, but slams possible into the other valve and creates pressure? Should I be looking for a way to truly dump return fluid directly into the reservoir? I think we may be getting close. Your thoughts. Thanks again for a everybody's help. Mark