john deere 27 c won't do zero turn

[dmason320]

Are you sure that pump 1 runs left forward and reverse? I'm just looking at the diagram and pump 1 is in front, and
on the left side of pump 1 is left forward (3a) on the right is right reverse (4a). The same for pump 2 (3b and 4b) Or is the control valve (3a and 3b) run only by pump 1, and 4a and 4b by pump 2 ?

 

[mg2361]

100%. Pump 1 supplies left propel 3A and 3B. Pump 2 supplies right propel 4A and 4B (see attached hydraulic control valve schematic).

 

[dmason320]

Thanks Mg2361 you are a huge help! I don't know what I would do without this forum. I felt for lines pulsing as I ran the drives forward and back but didn't get what I needed so I drained the tank again and am in the process of switching the lines back on the rotary so I know where I was at that point

 

[dmason320]

Before you switch hoses maybe you could answer a question first. Are you saying that in going forward one pump has pressure and when you run the same track in reverse the other pump is feeding it?

The relief valves for the travel circuits are in the travel motors and not in the main control valve. Forward travel is one relief and reverse travel is the other relief in the same motor.

Can you elaborate on the relief valves and how they work? I switched two lines on the rotary that I thought were the problem (right reverse and left reverse) but the drives just worked on the opposite lever than they were supposed to.

 

[John C.]

If you pull the covers off on the inside of the track frames behind the sprockets you will see the travel motors. The reliefs are two cartridge valves with adjustable screws held from turning with lock nuts. You check the pressures for each direction by putting a pin in an tooth groove and turning the final until it locks against the track frame. With a gauge plumbed into a fitting between the pump and the main control valve you can check the relief pressure for that direction. Then reverse direction and put the pin in the opposite way to lock the track the other direction and check pressure. They should be nearly the same. If one side is lower than the other you can swap the cartridges and check again. If the pressures switch sides you can just adjust the cartridge up to the same as the opposite side. If the pressures don't switch sides you likely have a swivel seal issue or a pump problem. Swivels are cheaper to reseal than pumps are to fix and reseal so that would likely be your next step.
Good Luck!

 

[dmason320]

I'm starting from scratch like in the shematic, I don't read a lot of these and could use some advice because it could be read two different ways.
Left forward and left reverse are the bottom two lines that run into the rotary. I have added a side view of that. I don't know if LR is in port D or above LF in C

 

[mg2361]

Try these.

 

[dmason320]

Thanks MG your the best!

 

[dmason320]

I reversed the propel lines at the track motors all it did was reverse the direction of the motor. there were no cartridge valves that I could see, the lines when right into the fittings attached to the drive motor. i guess all I can do now is pull the rotary and rebuild it. There are 4 bolts on the bottom that seem fairly straight forward to remove. I'm concerned with these two rusty bolts on top. they seem to attach to a bracket coming from the top on one side of the rotary. I don't know if this bracket is attached to the rotary or not, the pictures don't show it.

 

[John C.]

Usually that is a bracket that makes the top half of the swivel turn with the house while the bottom half stays put in the carbody. On most of the machines that I've worked on, that bracket has a boss and a pin that attaches to the swivel housing. There has to be some flexibility in the connection so tops are not bolted down hard in place.

 

[dmason320]

Has there been repairs to this machine? Hoses replaced and connected to the wrong ports? Someone has turned pump 1 relief way up also. Top of spec is 3280 psi. You may have to check that the hoses from the control valve to the rotary manifold are correct as well as from the rotary manifold out to the drive motors. Also the pilot hoses that stroke the spools may have been installed incorrectly if one or more of them has been replaced. I attached a diagram of the propel main line connections, but do not have one for the pilot line connections.

UPDATE:
I pulled the rotary to rebuild it with a new seal kit. The very bottom seal was gone so it would have began to leak anyway at some point. The other seals seemed intact so I don't think my problem came from any of those. I did realize that 3 of the lines going to the rotary were in the wrong ports, right reverse was the only one in the right place. I compared the schematic to the rotary with air pressure in each port and I am confident that the schematic is correct so I will switch the three lines from the pumps to the correct ports on the rotary. I guess that is not where my problem ends. The three propel lines that go to the pumps need switched also. Don't you agree?
I also called the previous owner and they eluded that some young guy did repairs to this machine and probably did not have access to any material for guidance.
For anyone doing this repair this is what I did:
rotate machine 90 degrees left for access to the rotary fittings
Drain hydraulic tank
mark bottom lines that go to propel motors with zip ties and remove wrapped with wire and tie back out of the way with blade lines.
mark and remove the four lines form the pumps on the starboard side and remove the small line on the bottom of the port side.
All those lines are accessible with normal 3/4 and 7/8 wrenches however the last two fittings on the port side rotate horizontally so I made two sized wrenches from two large crow foot wrenches that i would never use. A 7/8 for those and 3/4 for the last two lines on the top. See photo. Now its time to put it all back together!

 

[mg2361]

Let me know how you make out when you get your hose routing straightened out. Just in case I attached a pilot system schematic for you in case you need it in the future.

 

[dmason320]

Thanks MG!

 

[dmason320]

Success! problem solved, I switched the three lines that where coming from
the pumps to the bulkhead that connect to the propel pedals twice and got it right.
Thanks for all the help!!

 

[dmason320]

Has there been repairs to this machine? Hoses replaced and connected to the wrong ports? Someone has turned pump 1 relief way up also. Top of spec is 3280 psi. You may have to check that the hoses from the control valve to the rotary manifold are correct as well as from the rotary manifold out to the drive motors. Also the pilot hoses that stroke the spools may have been installed incorrectly if one or more of them has been replaced. I attached a diagram of the propel main line connections, but do not have one for the pilot line connections.

I want to turn down the relief pressure on pump 1, Also I may add a hydraulic thumb and want to also make sure the relief on the auxiliary is set lower than the bucket curl so I don't damage the thumb. Can you point me in the right direction on how to do this?

 

[mg2361]

Do you ever plan on running a breaker?

 

[dmason320]

No

just a two way hydraulic cylinder for the thumb

 

[mg2361]

As far as the pump 1 pressures all the info you need are in posts #8, 10 13 and 14. As for your thumb see attachment.

 

[dmason320]

Thanks for the help MG!