Hi I recently purchased a Jinma 254 (Tractor King branding) with a FEL. Fel works and the 3point would raise but not lower. I checked the 3point adjusting valve knob and it was closed all the way and would not budge. I gently rocked it with channel locks and freed the knob and the hitch lowered down but now the 3point hitch will do nothing. Is it possible to just completely remove the knob adjuster shaft to make sure the needle seat (its held on by a roll pin 4 and 6) is still attached to the shaft. Thks Rob
99-01 Jinma 254 3 point wont lift
- Thread starter Cherryman
- Start date
I found this info on this forum " Usually the piston seal fails when the piston travels too far and the seal goes out over the edge of the cylinder while under pressure, blowing it out. So after you replace the seal you have to adjust the piston travel."
Is it possible that with my valve opened fully the 3 point dropped to the ground and traveled too far blowing the seal? it was alrdy almost on the ground with the box blade installed. Thks Rob
Is it possible that with my valve opened fully the 3 point dropped to the ground and traveled too far blowing the seal? it was alrdy almost on the ground with the box blade installed. Thks Rob
piper184
Gold Member
I doubt that the seal failed at the bottom. This usually happens if the piston extends (raises the arms) too far.
The knob on the valve usually has a set or "tension" screw that keeps it in place. If this is too tight then it makes the knob hard to turn.
Basically all this valve does is regulate the flow of the fluid as it exits the cylinder and returns through the control arm valve which dumps the fluid back into the tank.
Question: If you screw the speed control knob all the way down, will the 3 point lift? If so, you may have a problem with the main control valve. If not, it is most likely the piston is not sealing against the cylinder. Usually the piston gets extended beyond the cylinder and will not go back in. Yours may have popped back into the cylinder but left the seal hanging on the outside.
You will need to pull off the seat and remove the top cover of the hydraulic tank for access to the piston so you can check the seal.
The knob on the valve usually has a set or "tension" screw that keeps it in place. If this is too tight then it makes the knob hard to turn.
Basically all this valve does is regulate the flow of the fluid as it exits the cylinder and returns through the control arm valve which dumps the fluid back into the tank.
Question: If you screw the speed control knob all the way down, will the 3 point lift? If so, you may have a problem with the main control valve. If not, it is most likely the piston is not sealing against the cylinder. Usually the piston gets extended beyond the cylinder and will not go back in. Yours may have popped back into the cylinder but left the seal hanging on the outside.
You will need to pull off the seat and remove the top cover of the hydraulic tank for access to the piston so you can check the seal.
quicksandfarmer
Veteran Member
The knob under the seat switched the hydraulics between the 3-point and the auxiliary. Could it be that it's set for auxiliary?
Not sure QSF (great name) the FEL and 3point never needed to be switched be4 if Im understanding your reply
Last edited:
Thks Piper184 for the response what seal(see pic) would I look for with the plate removed? Extra note the 3 point can be lifted by hand with little resistance. The only set screw I see attaches the plastic knob to the metal threaded shaft.
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piper184
Gold Member
The knob under the seat does not switch between 3 point and aux, it's sole function is to control the speed at which the 3pt lowers.
The 3 point lift cylinder is only a one way cylinder in that there is only pressurized fluid on one side of the piston and it takes an external force (weight on the arms) to retract the piston into the cylinder.
On my 284 there is a small set screw (#11) in the housing that runs in and presses on the threads of the screw that the knob connects to. This provides friction to keep the knob setting from changing with vibration.
The reason you can manually lift the arms is that there is no hard linkage between the piston rod (#27) and the the rocker shaft arm (#40). That is why 3pt lifts "float" and have no down pressure.
The rod numbered 63 goes between the lift arm and the control lever. It has an adjustable stop on it that forces the control lever to pop out of "up" detent and go back to "hold" detent before the piston slides too far out of the cylinder. This is what limits the up travel. If that gets out of adjustment it can let the control valve keep supplying fluid until it pops the piston (#18) out of the end of the cylinder (#16). At this point the whole linkage is free to just fall out of place and just let the rocker shaft and lift arms free fall all the way down. Part number 42 is a stop pin that is supposed to prevent the piston from coming out.
You are lucky that you only have to take off the top cover to see what is going on. On my 284 I have to remove the whole tank with piston and rocker assy and turn it over to remove the cover. I had to remove mine once to get to the axle gears underneath. It's HEAVY!
You might be able to drain the fluid and remove the rear cover and get enough access to see what is going on. If you are real lucky you can get enough room to put it back together that way but I would probably just pull the top cover for easier access and better visibility.
The 3 point lift cylinder is only a one way cylinder in that there is only pressurized fluid on one side of the piston and it takes an external force (weight on the arms) to retract the piston into the cylinder.
On my 284 there is a small set screw (#11) in the housing that runs in and presses on the threads of the screw that the knob connects to. This provides friction to keep the knob setting from changing with vibration.
The reason you can manually lift the arms is that there is no hard linkage between the piston rod (#27) and the the rocker shaft arm (#40). That is why 3pt lifts "float" and have no down pressure.
The rod numbered 63 goes between the lift arm and the control lever. It has an adjustable stop on it that forces the control lever to pop out of "up" detent and go back to "hold" detent before the piston slides too far out of the cylinder. This is what limits the up travel. If that gets out of adjustment it can let the control valve keep supplying fluid until it pops the piston (#18) out of the end of the cylinder (#16). At this point the whole linkage is free to just fall out of place and just let the rocker shaft and lift arms free fall all the way down. Part number 42 is a stop pin that is supposed to prevent the piston from coming out.
You are lucky that you only have to take off the top cover to see what is going on. On my 284 I have to remove the whole tank with piston and rocker assy and turn it over to remove the cover. I had to remove mine once to get to the axle gears underneath. It's HEAVY!
You might be able to drain the fluid and remove the rear cover and get enough access to see what is going on. If you are real lucky you can get enough room to put it back together that way but I would probably just pull the top cover for easier access and better visibility.
Thk you so much for taking the time. My model has no set screw (11) anywhere in the housing. When I purchased the my 254 the diverter valve 3pt arm was broken off and they were using vice grips. I removed it and welded on a new arm but the linkage arm(63) was not reattached. I thought it was just a way to have a implement memory. I will take the top plate off today and post back thks for the help... Rob
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Affordable
Advertiser, Platinum Member
There is a set screw in the plate that the adjusting knob is on ? Did you loosen it?? If the seal on the 3- point piston is bad, you just remove the back cover where the top link attach's, and the cover with the adjusting knob, you can then get the piston out and reseal it , not a big job and you don't have to remove the lift box??
Tommy
Affordable Tractor Sales
"Your Jinma Parts Superstore"
www.affordabletractorsalesco.com
979-865-4002
Tommy
Affordable Tractor Sales
"Your Jinma Parts Superstore"
www.affordabletractorsalesco.com
979-865-4002