Bent rods in loader arms?

[pmmully]

Well, my education into the FEL 1150SG loader bucket curl malfunction on the used L48 continues.... the used dealer called today and said both rods in the bucket cylinders are bent. I expected the relief value to not let that happen? Well, I guess that assumes there is a relief valve in that circuit. The causes I have read about so far are improper installation alignment and excessive side loads, or an impact at speed. All make sense. It is possible tooling around with the bucket hanging down like a limp you know what could have done it?

Anyway, it's on the way to being fixed with new rods, at my expense. They tell me it did not leave that way. I know I never lifted a thing... will check on the dude I left it with, but he owns his own L31 so I would be surprised if he really did do something not kosher, but maybe. It ain't worth arguing about.

I know of my ASV skid steer, you could hardly hurt the thing it was so strong. But then again, it was a steer, everything was a lot shorter and stouter.

 

[JOHNTHOMAS]

Confession time. I had my arms lifted high on almost new B2650 (I think) and was using a front hoe type digger and my arms got bent. Extreme pressure with fully extended arms logically, now that it happened to me, to bend. You say you didn't do it but someone else was using your tractor. Imagine arms fully lifted/extended and digging with a backhoe/front hoe and the pressure on those arms to bend, had arms/fel raised high so I could see better where I was digging instead of extended stretched out and digging.

 

[ptsg]

Back dragging with the loader and possibly hit something hard can bend the rods of the curl cylinders. If you search on TBN, you'll find loads of threads just about that.

It's a lot of rod extending out without any support, so something will give.

The relief valves only actuate when the spools are moved. Once the spools are centered, there is no relief valve on the work ports to prevent damage. At least on tractors. I got a deal on a loader valve of a full-size industrial backhoe (either Case or CAT) for my homemade loader and it did came with work port relief valves, anti cavitation valves and check valves that makes two function operation a breeze.

 

[pmmully]

LOL, the truth will come out, one way or another , a combination of beer, whiskey, and guilt, works every time.

I just meant that there was nothing on the site that I could imagine being heavy enough to bend cylinders on the curl function when the spool was moving into the curl position. In that scenario, the relief valves should function (per PTSG). That does not mean that cockpit error did not occur as I could see once the curl-spool completed, and the lift was actuated, and the rods were extended at all, that it could happen. Now I could see side loads as well, and the back dragging without it being in float being a real issue. Tractor loaders have such long curl arms, something I did not consider.

Or, those rods were already not right, and I missed it on purchase.

This is all part of my learning curve. When all done, I may see myself going to a compact excavator/steer combo. It will depend upon the jobs I get in the next year.

 

[Smokeydog]

Relief valves are to protect the pump. None on a closed valve circuit.

I installed a pressure gauge on the M59 loader lift circuit along with hydraulic accumulators for a soft ride. Ball valve to select on or off.

Monitoring real time pressure with 10,000 psi digital gauge. Interesting to watch the pressure while working. Dead head lift pressure 2710psi against the relief. With the FEL grapple grubbing out trees and roots, lifting then curling and pushing forward could reach over 5000psi. Two external forces increasing the loader lift circuit pressure. The curl function and the tractor wheel traction.

I’m sure if I had a gauge on the curl circuit I could get similar pressures. What you don’t want is high pressure spikes when cylinder rods are extended. That causes the most structural stress. Back dragging with bucket cutting edge especially with cutting edge perpendicular to the ground, ie curl cylinders extended. Best to back drag with heel of bucket for machine ergonomics. Pushing with bucket at dumping angle like snow plowing and momentum sudden stops would put major cylinder rods stresses.

A technique I seen with larger backhoes was to dump angle the front bucket and raise the machine up on the outriggers for a better anchor while digging. Did this too with a Ford 4500 without problems. That puts a lot of stress on the extended curl cylinder rods while backhoe digging. Might not be best for our smaller machines.

L48 are tough machines. Drooled over a couple before finding the M59.

 

[5030]

Back dragging with the bucket in full curl (rams fully extended) is a sure fire way to bend them, especially when you impact something that won't move easily. Hard lesson to learn, expensive too. The rams can be straightened but it's a time consuming and expensive job.

 

[pmmully]

All great stuff, thank you. I am sure there was a bit of cockpit error moving a very large stump. The timing fits also.

It's ok, I would have made the same mistake coming from the steer. Those things are tough as nails in the loader department. I believe the hydraulic shop is installing new rods, somewhere in the $350 range, not sure if that is one or two. I will not be lending it out anymore, another lesson learned.

 

[oosik]

My story - read 'em and learn. Back dragging with the Rankin tooth bar on the lip of the bucket looked like such a great deal. The stories told by TBNers changed my mind. If I EVER do any back dragging it's with the heel of the bucket and the curl cylinders rods fully retracted. Besides the rear blade fully reversed works just as well, or better. Thank you - TBN.

Strange - in all the 37 pages of the Front Loader Op Manual - not one word of caution about back dragging. Perhaps they never considered this as legitimate use.

 

[s219]

The relief valve will prevent you from doing damage when using the hydraulics to apply force. But nothing will prevent you from doing damage when loads are applied to the cylinder externally, through the wheels/traction or some sort of push/pull. Many horror stories here on TBN about bend rods when someone was back dragging, pushing forward, or pushing/pulling against the loader with wheel traction.

 

[ruffdog]

If the cylinders are fully extended, there is very little overlap between the rod/piston and the body of the cylinder. It doesn't take much pressure to tweek them.

How NOT to break your loader while back dragging - YouTube