Construction and other equipment - 715 backhoe loader question

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715 backhoe loader question

Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Construction and other equipment
Forum Description: everything else with orange (or yellow) paint
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=21256
Printed Date: 18 Jul 2025 at 9:57am
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Topic: 715 backhoe loader question

Posted By: ndhoser
Subject: 715 backhoe loader question
Date Posted: 23 Nov 2010 at 3:33pm

I have a 715 that lost the rollback on the front end loader. Everything else works, lift, lower, dump, even the self level ( as long as I'm raising. As soon as I let go of the lever the bucket dumps). The serial number is 1708. It uses a Gresen Valve that my manual has a description of, but no diagrams. Would anyone have any info on this valve? it would be greatly appreciated.

Replies:

Posted By: Coke-in-MN
Date Posted: 23 Nov 2010 at 5:10pm

The valve body should be single lever control with side to side being bucket, fwd. back being lift and lower. Somehow your linkage is off and not allowing valve body to remain in neutral position for bucket.

Raise the floor plates and check all the linkage for proper movement .

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Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something.
"Challenges are what make life interesting; overcoming them is what makes life meaningful."

Posted By: Dave A
Date Posted: 23 Nov 2010 at 6:13pm

If it is not a linkage. Check relief valves. Think the bucket and loader run two differant PSI.

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Play the game for more than you can afford to lose... only then will you learn the game.
Winston Churchill

Posted By: Dave A
Date Posted: 23 Nov 2010 at 6:16pm

Hey I got a question for the AC loader guys. What keeps the bucket level when lifting. When raising the loader the bucket rams slowly extend

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Play the game for more than you can afford to lose... only then will you learn the game.
Winston Churchill

Posted By: Coke-in-MN
Date Posted: 23 Nov 2010 at 8:10pm

The linkage is set to allow the bucket to curl to keep the load from spilling and from dumping over the top side also . You will notice there is a rod on side of loader arm which attaches to bucket linkage that gives you level position of bucket and can be gauged for dig positioning. Not a real self leveling unit but close.

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Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something.
"Challenges are what make life interesting; overcoming them is what makes life meaningful."

Posted By: ndhoser
Date Posted: 24 Nov 2010 at 9:58am

Dave,

In this particular unit the oil from the rod end of the lift cylinders is directed through the self leveling section of the valve to the barrel ends of the bucket cylinders and the rod end of the bucket cylinders flow back through the self leveling section to the sump, hence my desire for the diagrams.

Coke,

I've checked the linkage and it's ok. I've torn the valve apart and checked for stuck spools and lift checks and can't find anything there either. I removed the lines from the barrel end of the bucket cylinders to see if they were bad and got no oil to come out when I tried to roll it back. I have good down force on the bucket so I have a hard time believing it is a cylinder problem, but I'm going to tear into them for lack of knowing what else to do. This is definately a stumper for me!

Posted By: Coke-in-MN
Date Posted: 24 Nov 2010 at 10:21am

Are you sure then there isnt a problem with the cylinders ? I did not figure in when you let lever go to neutral the bucket uncurled.

I would look close at the cylinders for internal leakage in one or both. I had a Pettybone loaded that did the same thing and one piston seal was bad allowing the oil past to the dump side.

Posted By: ndhoser
Date Posted: 26 Dec 2010 at 3:54pm

I finally got around to putting seal kits in my bucket cylinders. Didn't help. It has to be something in the valve. I don't really want to change all the plumbing in order to fit a new valve in there, but I don't think I have any alternatives.

Posted By: Coke-in-MN
Date Posted: 30 Dec 2010 at 8:30pm

Unsure if that has the regenerative circuit in that valve body also to bypass oil back to unload side of cylinder , you would have to check the manual. Just seems strange there would be that much leakage in valve body.

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Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something.
"Challenges are what make life interesting; overcoming them is what makes life meaningful."

Posted By: D-17_Dave
Date Posted: 30 Dec 2010 at 10:44pm

You stated that you repacked the bucket cylinders. Did you repack the boom cylinders. I don't know anything about this tractor but with the description of the circuit described above if the boom cylinders are blown it could cause the same effect. Just a thought.

Posted By: ndhoser
Date Posted: 02 Jan 2011 at 9:37am

Here is what the book says about the bucket section:

The bucket section is a 4-way section with the "A" work port connected to the barrel ends of the bucket cylinders (Figure I). The bucket cylinders are connected in parallel. The bucket section spool has 3 positions and is spring centered to neutral. Pushing the spool in, (Figure J) directs oil past the lift check and out the "A" port to extend the cylinder rods and dump the bucket. A floating check between sections prevents oil flow back into the level section work port. An anti-cavitation ball check, located in the lift checkplug assembly, prevents the oil from flowing back into the work port of the self-leveling section. An anti-cavitation ball check located in the lift check plug assembly, prevents bucket cylinder cavitation, when the bucket "dump" over center, by allowing the oil to flow from the sump passage into the "A" port cavity.

Pulling the bucket section spool out, (Figure K) delivers oil past the lift check and out the "B" work port to retract the bucket cylinder rods and "roll-back" the bucket.

Posted By: Coke-in-MN
Date Posted: 02 Jan 2011 at 10:16am

Then it sounds like that check valve(ball) has a problem in its seating or sealing the regen port.

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Faith isn't a jump in the dark. It is a walk in the light. Faith is not guessing; it is knowing something.
"Challenges are what make life interesting; overcoming them is what makes life meaningful."