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SEE pressure reliefs

Pinsandpitons

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Ive been playing with check valves and pressure reliefs to boost the stength of the loader. All i want is to lift the front tires off the ground, I don’t feel that’s too much to ask. Anyway, after adjusting the pressure relief at the valve block with no success I removed and installed backwards the pressure relief/check valve on the loader frame (#15 above) as a test to see if that’s where the pressure was leaking out. Success! I think I’ll just remove that and cap the lines as the pressure relief on the valve block should be plenty. Here’s my question, does anyone have any idea what #9 is below? It’s marked as a pressure relief, but I have no idea how that could be if it’s only on a single hydraulic line. A check valve perhaps, but what would it be checking? Fluid has to flow in both directions through that line for the loader to work so I’m just confused. Ideas?

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tennmogger

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Could it be a check or restrictor valve in a return line? Purpose could be to stop bucket from falling immediately in float? Keeps bucket under control?
 

Pinsandpitons

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A flow restriction... You’re probably right. Of course that would work in both directions, slowing everything down. I’ve been scheming on replacing the front hydro pump with a higher volume unit ‘cause the loader speed is painful when you’re actually trying to get things done. I’ll see what it looks like when I take it off.
 

tennmogger

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A flow control valve is not like an orifice that works both ways. It acts as a check valve, with free flow in one direction but restricted flow in the reverse direction. Some are fixed flow, others are adjustable, and this looks like a fixed type.

What rpm are you running when the hydro output is too low?

I have contemplated a higher volume pump for the front of a 406 (for more flow at lower rpm) but realized the single belt capacity would probably limit pump rate and pressure anyway, so I left it alone :)
 

Pinsandpitons

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I have them somewhere. It's an internal gear pump (low noise, med pressure) with I think about 11cc per rev (memory). So pretty small for the application. I'm not sure why they designed it that way, but it's way undersized IMHO. I was thinking about making the pulley smaller to run it at a higher speed (need to be careful of max engine rpm), or just putting a larger displacement pump in (may run into hose size issues and would need to install a flow limiter so as not to oversupply the tool circuit). I have a 28cc open center external gear that I could use but it would be far from a bolt up. Different mount type, shaft size, fitting type etc. I would prefer to make the existing system work better as much as possible.
 

Pinsandpitons

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A flow control valve is not like an orifice that works both ways. It acts as a check valve, with free flow in one direction but restricted flow in the reverse direction. Some are fixed flow, others are adjustable, and this looks like a fixed type.

What rpm are you running when the hydro output is too low?

I have contemplated a higher volume pump for the front of a 406 (for more flow at lower rpm) but realized the single belt capacity would probably limit pump rate and pressure anyway, so I left it alone :)
I don't know how I missed your post, but I did. All rpm's is the answer, idle especially, but it's hard to get anything done when you're always waiting on the implement to move. Maybe I'm too used to a Cat backhoe, but no matter what I'm doing, moving snow, backblading, moving ditch spoils, I'm always waiting for that loader to catch up. And yes, I stand corrected as it's not an orifice. Either way I'm not sure I really want the float slowed down that much. Maybe I'll try it without just to see, but the point is I'm looking at the system as a whole and trying to figure ways to improve the speed and power without blowing something up. I can be smooth, but I need the option. Right now it's pretty much an on or off operating style, it's too slow to need to feather the valves.

Understood about the can of worms opened up when a different pump is contemplated, but I'm a tinkerer by nature. Especially when it could be so much better.
 

thingamadigger

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People can with a little practice, dig the bucket into the ground at just the right angle, then drive forward slowly in low which will raise the front wheels..but I concur it would be nice to lift the truck with that bucket with hydraulics alone, which in practice works on most front bucket backhoes, but not with my SEE. I too took a look at doing this, even altering the geometry of the front tilt lifter bars, which seem quite delicate and a little flimsy. Next to the hydraulics, they appear to be the weak link in this system from a backyard engineering perspective, with no lateral stability from them once you did manage to lift the truck. My experience with german engineering concludes this limitation was intentional and I can only imagine the discussion as to every possible situation where lifting the truck with both implements could cause a disaster leading to a determination that the bucket should not be able to accomplish this task. After getting completely stuck in soft clay mud and burying both axles, I can tell you it was frustrating not to be able to use both implements to crawl out, and with the front wheels in holes, the rear alone was not able to lift and pull me out. Getting unstuck took tying a 60hp tractor in neutral with all the chain I had on hand to the backhoe, and then a F350 with a 20000lb winch all the way out to the front of the tractor. Between 4WD low reverse, the winch, and the backhoe assisting as a lever, we were free again. Another modification I am considering is an attachment for the rear bucket that once quickly clamped on can be driven down into the earth a few feet( something with 3+ rebar fingers that levers onto the backhoe bucket maybe) to then allow the strength of the backhoe to lift and pull me backwards out of a predicament without simply taking a bucket full of soup and moving it in the wrong direction!

The questions are;
1. do we want to lift just over half the weight of the truck with the bucket, barely getting the front wheels off the ground, or once the backhoe has lifted the rear, will we be moving the full weight with the bucket in order to completely raise the entire vehicle? If lifting the front first will there be enough holding power to keep it airborne when lifting from the rear second?
2. Do we want to lift the weight of the whole truck with just the tilt lever, just the up lever, with either lever, or with a magic combination of them both simultaneously?
3. Do we want more pressure? Faster flow rates, or both?
4. Is the most economical option plumbing the rear pump to the front for one or both operations? Is there a way to do this with a separate lever/shutoff combination for just this purpose, leaving the original setup in place?
5. Will I have to wear an improved "safety shirt" once this is accomplished? :)
 

Sgt Jiggins

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I'm curious to see how this turns out. I have wondered the same many times: "why can't I lift the front end off the ground?!".

Interestingly, I discovered the front end is fully capable of lifting the front of the SEE off the ground. It was during one of those moments I wound up putting the frontend in a ditch. I had had the bucket in the air, so the truck stopped falling into the ditch when the bucket came down on the opposite side of the ditch. After collecting my thoughts, I decided I'd try to lift the front... just to see. Imagine my shock when the frontend came Right Up&Out of the ditch. With the SEE leveled off, I put it in reverse, slid back across the ditch, and went on about my day.

I guess what I'm left thinking is, it may be more than just a flow/pressure issue. It may just be those Germans figured out it wasn't going to be able to leverage itself at that point anyhow and just left it at what it is. Just my 2c.
 

tennmogger

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A slipping pump belt can severely limit pressure, and you'll never know it. On civilian 406 mogs it's common to find an SAE belt on the hydraulic pump, non-metric, and its a non-fit. A visual check: If the belt is buried in the v-pulley, it is either worn out or the wrong size. The correct metric belt will ride high on the pulley when new.
 

Pinsandpitons

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Yes, All good points. I did in fact break the front hydraulic drive belt when I reversed the pressure relief valve on the front loader frame. It was badly worn and while I had the belts I had not gotten around to replacing them. Needless to say they all are replaced now.
On the interesting topic of geometry and downstream consequences of increasing front loader power, I think careful adjustment of pressure relief valve’s could be the answer. Also what’s the harm in picking the whole truck up from the front and rear? There are lifting points to do just that. After all these vehicles have been airdropped by parachute and were designed to do so.
 

SpoiledSpud

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Also what’s the harm in picking the whole truck up from the front and rear? There are lifting points to do just that. After all these vehicles have been airdropped by parachute and were designed to do so.
Well, the machine may have been designed to be picked up or airdropped from the lifting points but probably not from the front loader itself. There are lifting points on the FOPS but I wouldn't suggest airdropping using those either.
 

Pinsandpitons

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Those are clearly not vehicle lifting points but only for that piece. Same as the small rings for the side modules. The 3/4" plate eyes front and back that are part of the implement mounts I think are what were used.
 
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