MF 135 3 point wont stay in one spot

[kool cat]

I borrowed my buddies Massey 135 but when using the 3 point hitch you cant set it. it will drift up or down. what ever way you last moved it
can anyone tell how to fix this?

some details
tractors around the 70's
has loader that runs off the 3 point hitch lift control
loader will do the same as the 3 point hitch
valve on transmission to control loader or switch to 3 point hitch

 

[redman135]

Are you using the POSITION control section OR the PREASSURE control section of the inside control?
When you use PREASSURE control you will have the problem you are describing.
The quadrant layout is "preassure control" on the forward 1/2, a small section with "constant pump" in the middle and the back 1/2 is "position control". All the way back is down position. The names may or may not be stamped into the metal. Decals were used on the last 135's.
Can you post a photo? Try to get any decal or words stamped into the metal in focus please.
Complicating things, in about 1971-1973 they changed the 3ph controls from straight position control to a dual "preasure/position control.
The outside lever is Draft control and should be in the fully up position all the time (only used when ploughing) .

 

[redman135]

Hello kool cat, The combination preassure/position control has a wide section on the flat of the quadrant and reduces by 1/3 at the position control section.
The change in width helps you know which section you are using if your are not familier with MF hydraulics.