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Unimog 406

16K views 69 replies 12 participants last post by  amamog 
#1 ·
hello All

I have a 406 agricultural spec mog. It has two levers under the steering column on either side with various slots and positions it can go into. Can someone please share a diagram to show what does each lever do in the different positions. My mog has a three way tipper bed, and 3 point linkage arms in the rear. It also has hydraulic pipes in the front.

your help will be appreciated.'


thanks Suveer
 
#2 ·
Good Morning,

Those two knobs are your hydraulic actuator levers. Open the hood and you will see two rods coming through the fire wall to a hydraulic valve with four lines coming off of it.

Each lever goes to two lines, most likely you'll find the quick disconnect connections just behind the left hand side head light, vertically mounted. Very inconvenient. I moved mine out front.

Each lever works the same, just for two different lines.

Push the lever forwards and it will create flow in one of the lines (lets call it A) while setting the opposing line (B) into "float" which allows the fluid to go back to the tank if you were using something like a double acting cylinder. Pull the lever back towards you and the exact opposite happens, the first line (A) goes into float and the opposite one (B) actuates. Using the other lever does the same but for lines C and D. You do have to figure out which is which though as A and C won't work as there is no way for the fluid to get back to the tank so you will be pushing fluid against a closed line. One of the two always has to be in float.

Another thing you can do is pull the lever back and down just a bit, where it will stay, and one spool will remain constantly flowing. this is good for a winch or some other rotating motor.

Finally you can push the lever up, where it will stay and both lines will be in float. This is what you'll do to let your dump bed drop. Also the three point hitch will be in full float with this setting.

Any one of the lines can go to the dump bed, it only needs one as it's a one way cylinder so you'll have to do some exploring to figure out which one. Someone may also have introduced a valve in a line so that the dump function can be turned on and off easily. Once you figure out which it is, you pull, or push the lever to send fluid to the dump bed, then pop the lever up to let it all drain back to the tank which allows the bed to drop. It's a good idea to keep the line in float when loading the bed as it will sag a little bit under the weight and settles down on the four pivot balls better instead of loading the gimble under the bed.

I hope that helps a little.
 
#4 ·
Britbike2001 thank you for the detailed explanation. I understand it much better. Thanks a million.

TKV000, if I can only get those diagrams in English, it will be awesome....I could keep a copy in the truck for qwik reference. But from where????? Maybe someone has this diagram on this forum.
 
#5 ·
Something else is bothering me now. I did a complete service on the mog. I changed the hydraulic filters and replaced with new transmission oil. After a week, when I go back to have a look, I see the hydraulic tank is empty. Where could the oil be gone. Did it leak out but I cant see too much evidence of this on the ground.... then then again it parks on a gravel surface. Are there any know culprits to look for regarding the leak?

thank you
 
#6 ·
If you have not been using the hydraulics then the PO could well have drained down the system for one reason or another and the fluid is slowly working it's way through the lines. Also the tipper cylinders are a five stage affair so have many point of leakage. I know mine leaks quite a bit but that just saves me the hassle of lubricating the parking brake..........

If you can, round up a hydraulic hose that you can tie two lines together with (if the original set up is still there, you should have four female quick disconnects behind the headlight) and circulate fluid through both circuits which will flush out any air and completely fill the system. Also cycle the dump cylinder.

Once that's done if you lose fluid, you either have a leak, which should be apparent or someone is stealing it.

Most of our vendors over here have the manuals in English. I'm not sure who you have down your way but anything can be shipped.
 
#9 ·
Thx guys. Appreciate it. Can u please explain this process to me Britbike. Forgive my ignorance.

If you can, round up a hydraulic hose that you can tie two lines together with (if the original set up is still there, you should have four female quick disconnects behind the headlight) and circulate fluid through both circuits which will flush out any air and completely fill the system. Also cycle the dump cylinder.
 
#10 ·
I hope this helps.

Thankfully once you've fooled with this stuff for only a short while, it gets pretty simple as we are simply applying flow / pressure or releasing it. No rocket science here.

Please note that this sketch is for only one lever. The other is exactly the same but just for the other two lines (C & D in my earlier post).

Do note that if you hook up the lines and can't get flow you just have to keep swapping one around until you figure out which it's pair is. Once you do, label them with color coding.

I've labeled mine so that I know which one always get's flow when the lever is pulled back too as I try to keep consistent with my connections as it sucks when the blade goes down instead of up or if the winch spins backwards. Reversible, yes. A pain in the neck when you want to get some thing done, yes.
 

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#11 ·
BRITBIKE..do i just connect the two pairs together which is next to the left head light and activate the levers so a flow is created to expel air. Is my understanding correct? Did u send a sketch. ?Cant seem to open it. Also.... if the oil is less will the pump make a screeching sound?
 
#12 ·
You have the plan down. Most trucks have four lines so with trial and error you will have to figure out which two go together but you will not hurt anything as the pressure relief valve will dump the flow to the tank if you are going against the wrong line. You will hear the sound when it does that. Just let off the lever, put it in float and rearrange the lines till you get the right ones. Then label them.

I did attach a .pdf to the last post and just confirmed that it's there so take a peek again. Hopefully it will help.

I would make sure the oil tank is full first of course (oil level half way through the round window) but the pump is the very lowest thing in the system so you would have to be extremely low on oil for it to screech.
 
#24 ·
There is usually a check valve or shutoff cock to turn the tipper on/off, look for a lever to swing. Usually, when the lever is in the direction "with the hose" that's open, 90degree's to the hose, that's closed.



Follow the lines from the tipper cylinder (also make sure only two pins are installed!) to see if you have one of those (top picture)
 
#26 ·
screeching

Amamog I am guessing the screeching is because you have the hydraulic circuits crossed plumbed somewhere so when you activate the lever the flow is restricted and so the pump starts slipping. I have experienced that same issue. If you can look while someone else activates the lever you will probably see the line initially shake or vibrate when the lever is activated. If I remember correctly mine happens when I connect the quick disconnect that runs from the front to the back on the wrong disconnect up front. #20 in the PDF I sent attaching to #25. You can see #25 points to both disconnects try swapping the one you are hooked into. Good luck. Bob (formerly "Bobmog" but now "Mcmog" because of the great password change. Thanks for whoever was the genius behind that move!)
 
#32 ·
Amamog I am guessing the screeching is because you have the hydraulic circuits crossed plumbed somewhere so when you activate the lever the flow is restricted and so the pump starts slipping. I have experienced that same issue. If you can look while someone else activates the lever you will probably see the line initially shake or vibrate when the lever is activated. If I remember correctly mine happens when I connect the quick disconnect that runs from the front to the back on the wrong disconnect up front. #20 in the PDF I sent attaching to #25. You can see #25 points to both disconnects try swapping the one you are hooked into. Good luck. Bob (formerly "Bobmog" but now "Mcmog" because of the great password change. Thanks for whoever was the genius behind that move!)
Mcmog, I am a bit confused now. Must the front disconnects be connected ( the two near the headlight) in order to use the rear 3 points arms and tipper bed. Apologies, I am really confused?
 
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