LA302 Lost Bucket Roll Back Function

[Rusty46]

I went back and reread this post. I did not pay ebough sttention when I saw you were disconnecting hoses at the cylinders. My apologies- your second test is basically what I wanted. If you got flow out of the base end of the right cylinder and the cylinder did not move the cylinder is bypassing.

Dan

Dan - Thanks! So does bypassing mean I need to have the cylinder rebuilt or possibly
replaced? Also is the right side bypassing cylinder preventing the left side cylinder from retracting when I try to curl? If so, is that because the left cylinder is losing retracting pressure thru the bypass, or what?

Thanks for all your help!

For clarification, my loader has only four quick connect pairs, all at the control valve. The four male ends (nipples) are mounted to the control valves and the four female ends (couplers) are mounted to the four hoses. The hose connections to the cylinders are all threaded connections.

 

[Rusty46]

ALL - Thank you to everyone for your input so far! I have tried to keep up with reading and understanding all the posts, but my inexperience with hydraulics and terminology has slowed me down considerably. Please stay tuned!

 

[TheOldHokie]

Dan - Thanks! So does bypassing mean I need to have the cylinder rebuilt or possibly
replaced? Also is the right side bypassing cylinder preventing the left side cylinder from retracting when I try to curl? If so, is that because the left cylinder is losing retracting pressure thru the bypass, or what?

Thanks for all your help!

For clarification, my loader has only four quick connect pairs, all at the control valve. The four male ends (nipples) are mounted to the control valves and the four female ends (couplers) are mounted to the four hoses. The hose connections to the cylinders are all threaded connections.

When I say bypassing it means pressurized oil entering the rod end is migrating past the seals and going out the base end without building pressure. It appears you are not getting enough pressure to curl the empty bucket so that's a pretty bad leak.

If you are getting pressurized oil flow out of the base end of the right side cylinder and its not retracting it is definitely bypassing. If no oil coming out of the other side its probably OK.

Somebody mentioned you rebuilt the cylinders previously. If so that might have been done incorrectly. My personal preference for these little loader cylinders is to replace with new. The added expense is minimal and a whole lot less work.

Parts manual seemed to show male couplers on the valve but functionally it does not matter.

I think you have identified the problem. Good luck with the repairs.

Dan

 

[07wingnut]

Check my post #11. If it is bypassing to the extent that there is no curl, it is unlikely just to be bad seals. If the cylinders were rebuilt, that means the nuts connecting the ram to the piston were removed, and then placed back in position. All it takes is for one to have not been torqued.

 

[Jasonized]

hmm.. it would still have to bypass, though, wouldn’t it? Because once the disks end up at one side, they would restrict the flow a bit…. Hmm…. Well, there is the hole where the bolt went through, so maybe not…

it would also easily explain the “sudden” failure, too.

 

[TheOldHokie]

Check my post #11. If it is bypassing to the extent that there is no curl, it is unlikely just to be bad seals. If the cylinders were rebuilt, that means the nuts connecting the ram to the piston were removed, and then placed back in position. All it takes is for one to have not been torqued.

Bottom line is if there is oil flow into the rod end and that oil is coming out the base end with no actuator movement something in one or both cylinders is bypassing big time.

At this point I would probably disconnect both cylinders from the bucket and do some individual testing.

Hook them to the valve individually and see what happens with no load on the cylinders.

if the left one works pin it to the bucket and see if it will curl.

Seems unlikely both would have failed sumultaneosly.

Dan

 

[Rusty46]

Bottom line is if there is oil flow into the rod end and that oil is coming out the base end with no actuator movement something in one or both cylinders is bypassing big time.

At this point I would probably disconnect both cylinders from the bucket and do some individual testing.

Hook them to the valve individually and see what happens with no load on the cylinders.

if the left one works pin it to the bucket and see if it will curl.

Seems unlikely both would have failed sumultaneosly.

Dan

ALL - I dropped the by-passing cylinder at the hydraulic repair shop today and got plugs for the hoses to that cylinder to see what the remaining cylinder does by itself. With the return line disconnected from the remaining cylinder, the cylinder discharges fluid, retracts and the quick attach rolls back, with the joystick in the roll back position. With both hoses connected to the remaining cylinder, the cylinder retracts and extends. I will update again when everything is back together.

Thanks for everyone's help!

Rusty

 

[DustyRusty]

ALL - I dropped the by-passing cylinder at the hydraulic repair shop today and got plugs for the hoses to that cylinder to see what the remaining cylinder does by itself. With the return line disconnected from the remaining cylinder, the cylinder discharges fluid, retracts and the quick attach rolls back, with the joystick in the roll back position. With both hoses connected to the remaining cylinder, the cylinder retracts and extends. I will update again when everything is back together.

Thanks for everyone's help!

Rusty

My experience has been that when one cylinder fails, the other one isn't far behind, so I have them both repaired at the same time. Saves a lot of work and lost time.

 

[GreensvilleJay]

Had the master cylinder of my 57 Willys professionally rebuilt at a well known shop. Great I got brakes ! get a ton of topsoil in it, come home down the Dundas hill( think steep and windy and long) NO brakes ! Pump like mad ,got some,rolled 3/4 way down Main Street. next day go to parts place, ask for a NEW master cylinder, guys comes with one with 30-40 years of dust on it, $125 he says. I say $50 saves you putting it back for another 3 decades.... Sold. Hour later I had REAL brakes.
Moral...buy new cylinders or have the old ones honed, miked out, new over sized ram and new seals.
If the inside of the cylinder is worn ( bigger) normal seals will NOT seal....

 

[DustyRusty]

Had the master cylinder of my 57 Willys professionally rebuilt at a well known shop. Great I got brakes ! get a ton of topsoil in it, come home down the Dundas hill( think steep and windy and long) NO brakes ! Pump like mad ,got some,rolled 3/4 way down Main Street. next day go to parts place, ask for a NEW master cylinder, guys comes with one with 30-40 years of dust on it, $125 he says. I say $50 saves you putting it back for another 3 decades.... Sold. Hour later I had REAL brakes.
Moral...buy new cylinders or have the old ones honed, miked out, new over sized ram and new seals.
If the inside of the cylinder is worn ( bigger) normal seals will NOT seal....

Most likely the "professional" that rebuilt your 57 Willys master cylinder clearly didn't know what he was doing. If the master cylinder was properly honed, and then washed in hot water with dishwashing liquid, properly dried, and new rubbers installed with brake assembly fluid, it would have worked as well as the 30 or 40-year-old new old stock master cylinder. In fact, whenever I use a NOS brake cylinder, I first disassemble and properly clean it of all old assembly fluid residue, and reassemble it with fresh assembly fluid. I venture to guess that the majority of people who rebuild brake hydraulic cylinders never heard of washing them after they are hones. They think that a spray of brake cleaner is sufficient to clean them, but that is the furthest from the truth. The same goes for honing cylinder walls and installing new rings. 10,000 miles later the rings are worn out because the cylinder walls were never properly cleaned.
I make no representations of how to rebuild hydraulic cylinders that are used on a tractor since I have never done one nor do I have any desire to learn how to do one at my old age.

 

[GreensvilleJay]

it was honed 'out of spec' (too much material removed) so the oil would 'curl' seals and allow oil to flow past them. I took it to old high school auto shop teacher, he dusted off his books, miked the master, shook his head. Same thing happens with engine cylinders and that's why when they're honed/worn too much, you need bigger piston and correct rings. a little wear, you can oversize the rings.

 

[DustyRusty]

it was honed 'out of spec' (too much material removed) so the oil would 'curl' seals and allow oil to flow past them. I took it to old high school auto shop teacher, he dusted off his books, miked the master, shook his head. Same thing happens with engine cylinders and that's why when they're honed/worn too much, you need bigger piston and correct rings. a little wear, you can oversize the rings.

It must have been bored, not honed. Honing to the point that it becomes oversized, would that forever with the stones that are in the brake hone. I have had cylinders that had some pits on them, and I couldn't hone them to be usable no mater how long I ran the hone.

 

[Rusty46]

ALL - I will update again when everything is back together.

ALL - Dropped cylinder at hydraulic shop last Wednesday and got it back Saturday am. Back together and everything seems to work well. Did some light pallet fork work yesterday. No problems. Will finish moving compost pile with bucket as soon as I can.

My hydraulic guy told me that the piston nut stripped off the rod. No other damage found. He reassembled and welded the nut on, at no charge.

Thanks again for everyone's help!

Rusty

 

[GreensvilleJay]

OUCH ! Curious as to how the nut 'stripped' off...I suspect something other than hand tools were involved during the original repair....

I looked up the parts..... The ram is $500 CDN.

Hopefully you'll get 2-3 decades of use before the next repair is needed.