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3 point lift capacity on MF 1655??


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#1 Luke ONLINE  

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Posted December 11, 2010 - 06:46 PM

Looking at purchasing a 58" overseeder and want to pull it with my 1655 but worried about it picking it up with full of grass seed! I'm not worried about keeping the front end down......have a bunch of john deere lawn and garden suitcase weights for the front. thanks Luke

#2 olcowhand ONLINE  

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Posted December 11, 2010 - 07:18 PM

I think 400lbs would be safe enough with front weighted to keep the front down. My 1855 lifts my tiller like it's not there and it likely tops 200+lbs or more. Of course the closer the main weight of the implement is to the hitch, the easier the lift.

#3 Luke ONLINE  

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Posted December 11, 2010 - 09:50 PM

Thats kinda what i was thinking.....400 to 500lbs max. Where does the 3 point get its oil from to raise and lower? Its not like a farm tractor with external lift cylinders........does the hydrostatic pump supply the ground drive plus 3 point lift system? If so can a fella turn the pressure up to gain more flow/pressure to lift more weight.....like a farm tractor? If yeah then has anybody done this and how do you do it? Thanks Luke

#4 olcowhand ONLINE  

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Posted December 11, 2010 - 09:53 PM

Yes, the charge pump that supplies the hydro it's oil also does the hydraulic lift functions. They are set to between 700 to 800psi, but that will lift a lot, so doesn't mean it's been tampered with, plus you don't want to bother anything in the system if everything is working properly. They are a simple valve which is adjusted by adding/taking away shims under a spring which seats the regulator plunger.

#5 Luke ONLINE  

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Posted December 11, 2010 - 10:02 PM

Hmmm, thats alot of psi already without monkeying without setting it higher.......I've set pressures up on our MF1155 and MF2775 farm tractors before but we're talking alot bigger systems with more capacity and bigger lines! This is just all out of "if need be" but whats the highest you could set pressure at without having problems.......don't need anymore of those if you know what i mean!! LOL! Luke

#6 olcowhand ONLINE  

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Posted December 11, 2010 - 10:23 PM

I'm not sure what pressures it would be cpable of, but it's the small pin that drives the gy-rotor in the pump that I would be concerned about shearing....that or reaming out the gy-rotor itself. I bought a JD F935 that wouldn't pull. Turns out someone had monkeyed with the pressure regulator & it ruined the charge pump rotor. New one was $275.00!! I bought a complete used hydro pump for $50 delivered instead.

#7 Luke ONLINE  

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Posted December 11, 2010 - 10:43 PM

Yeah thats the problem screwing with stuff and trying to get the max out of it! Opens up another can of worms! My luck I'd shear the key in the pump and the pieces would tear the pump up! Maybe I'll do some testing with tractor weights to see what it'll do! Will let ya know what i find out! Thanks for your time Dan! Merry Christmas! Luke

#8 massey driver ONLINE  

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Posted December 11, 2010 - 10:45 PM

I'm not sure what pressures it would be cpable of, but it's the small pin that drives the gy-rotor in the pump that I would be concerned about shearing....that or reaming out the gy-rotor itself. I bought a JD F935 that wouldn't pull. Turns out someone had monkeyed with the pressure regulator & it ruined the charge pump rotor. New one was $275.00!! I bought a complete used hydro pump for $50 delivered instead.


when I first put the loader onto my 1655 I couldn't get it to work properly from just using the charge pump. There's a little story to this so bear with me.At the time the hydrostatic was giving me problems as well so I had taken it in to a guy I know who repairs them.He Had to replace some parts in the unit to get it to work .I mentioned to him about it not working good for the loader and he said he'd fix that for me.Well as it turns out he increased the pressure by making a different shim for the spring.He ended up having to rebuild the charge pump again as when the pin broke it scored the pump.So the story here is that the setting is only supposed to be 750 psi to be safe and not shear that pin,which will score the pump.I ended up putting on a extra pump that's driven off the motor and this works perfect.Larry

#9 ducky OFFLINE  

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Posted December 11, 2010 - 10:50 PM

when I first put the loader onto my 1655 I couldn't get it to work properly from just using the charge pump. There's a little story to this so bear with me.At the time the hydrostatic was giving me problems as well so I had taken it in to a guy I know who repairs them.He Had to replace some parts in the unit to get it to work .I mentioned to him about it not working good for the loader and he said he'd fix that for me.Well as it turns out he increased the pressure by making a different shim for the spring.He ended up having to rebuild the charge pump again as when the pin broke it scored the pump.So the story here is that the setting is only supposed to be 750 psi to be safe and not shear that pin,which will score the pump.I ended up putting on a extra pump that's driven off the motor and this works perfect.Larry


10-4 on that one Did the same thin myself a long time back. 750 PSI NO MORE ont he charge pump.

#10 Luke ONLINE  

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Posted December 11, 2010 - 10:50 PM

Thats good to know! Note to self....."keep hands off the charge pump setting" Thanks Larry, I'm gonna see just how much weight she'll lift useing front tractor suitcase weights.......u ever pushed the envelope and checked the lift capacity on your 3 point? Thanks Luke

#11 Luke ONLINE  

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Posted December 11, 2010 - 10:52 PM

Thanks ducky........appreciate the reply! Luke

#12 hydriv OFFLINE  

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Posted December 12, 2010 - 12:12 AM

My advice would be to leave the relief setting on the hydro pump alone. I'd just put the seeder onto the three-point and then lay the bags of seed on top to see if it will lift the implement when it's full. The leverage of the implement is going to affect what the 3 point will lift. The closer in to the center line of the lift arm holes, the easier it is for the 3 pt to lift the weight.

Now let's say for a second that your hitch won't lift this unit and this is an ongoing need to use this device. One solution is to remove the cylinder from the hitch and replace it with another one that has the same stroke and rod diameter but is larger in diameter. If your cylinder is 2 inch right now and you go to a 2 1/2" or 3" diameter cylinder, you will vastly increase the amount of weight that hitch will lift. There is math available to calculate the difference between the stock cylinder and the larger replacement. Of course, a new bottom mount for the cylinder would have to be fabricated and welded to the bottom of the hitch plate but that's a minor issue. The hitch will rise up a bit slower and fall a bit slower but not by a lot. You don't want to go crazy here but I bet a half inch larger will make the difference.

#13 TUDOR OFFLINE  

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Posted December 12, 2010 - 07:41 AM

According to Sundstrand in their Bulletin 9679, Revision C, June 1978.

"Implement Flow & Press: 1-3 gpm with relief pressures from 700 to 1000 psi (optional)"

The MF4850 tiller is supposed to weigh 320 lb., without the extra dirt stuck to it.

An increase in cylinder diameter from 2" to 2.25" will yield a 25% increase in lift capability with a corresponding increase in time to lift/lower.

I'd be more concerned about the pin and bracket holding the cylinder on the tractor. Mine was bent from stock pressure and cylinder size when I got it 28 years ago, although that could be from pulling something with a 3PH implement.

Bob

#14 Luke ONLINE  

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Posted December 12, 2010 - 04:44 PM

Tudor......1000 psi optional??? Everybody tells me no more then 750 psi.......was there a option available on a pump upgrade to gain 1000 psi? Luke

#15 TUDOR OFFLINE  

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Posted December 13, 2010 - 08:09 AM

I would make a guess that it's just a shim or a heavier spring in the relief valve to bump the relief pressure up. The pump itself doesn't care. The housing is cast iron and 1000 psi is not a lot of pressure compared to what the main pump can withstand. The casting for the charge pump would be the limiting factor and I don't think I'd trust it too much beyond 1000 psi. unless I had a spare close at hand.

I'm just reading and quoting from Sundstrand's literature. I never tried it but these are strong, tough units.

A bigger concern is the effect on the tractor hydraulic support structure. It's not all that strong to deal with a 33% increase in force!

Bob

Edited by TUDOR, December 13, 2010 - 08:19 AM.





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