MH50 rockshaft

Brendon Warren

Well-known Member
Aanybody ever had to deal with a seized up rockshaft? I just bought this one. I put a water pump on it and now I'm working on the hydraulics. The arms were stuck raised. I have the lift cover off expecting to find something wrong with the piston. Nope just the arms are stuck. I've gotten them to move with a hammer but they aren't moving freely. With the way the rest of it was wore you'd have expected them to be sloppy.
 
I had that problem with a 245 that the PO used with a fertilizer sprayer. Had to press out the rockshaft and all the splines were ruined. Went to salvage yard and got another. Broke my Harbor Freight press trying to get it out. Took new bushings as well. Think some only come out in 1 direction.
 
Hello Brendon,
It is not uncommon for the cross-shaft to seize in the bushes. A customer bought a 135 recently and found that he had to actually stand on the lift arms to make them go down. Have you checked whether the ram arm in the centre of the shaft is seized in the shaft? It has little more than one eigth of an inch sideways movement so you'll have to check closely if it is seized or not. If it is the bushes seized in the cover it should not take a lot of force to drive them and the shaft out with a sledge hammer. If the ram arm is seized on the shaft and you have been able to drive the shaft from right to left as you stand behind the hydraulic then that is another matter. Being very difficult to handle I made a frame, part of which bolts to the bench to hold the cover steady whilst allowing the arms full movement and access for adjustment. The cover below had the ram arm seized. After heating it and generally hitting the you know what out of it I decided that cutting it was the only answer. I drilled a line of connecting 1/4" holes across it and then cut as many pieces out of it as I could with a 4" angle grinder and thin cutting disc.
With everything that I could cut out of it, it was then time to try and prise that two sides apart to release their grip on the shaft. I was then able to drive the shaft out.
There are several different ram arms fitted so make sure that you get the right one. The one fitted was a non-genuine item with different machining tolerances to the original. There is absolutely minimal clearance between the ram arm and the crown wheel...so much so that every time the linkage was raised the tractor would go forward slightly due to the two fouling. Make sure that you have clearance.
DavidP, South Wales
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The ram arm is free. Sounds like I'm lucky there. You sure are right about it being awkward to handle especially by myself. So you're saying it should drive out to the left? I did this before on my 65 and don't remember it being that difficult. In fact I remember it being one of the first times I asked for advice on this forum. Maybe 7 or 8 years ago. All my 65 book says is removal is evident. I have the old bushings from then and they fit over the splines and are very loose. I guess I see why the newer ones have grease zerks.
 
Hi, don't know if US tractors are any different but in the UK they stopped fitting grease nipples to the cross-shaft in around '69. There was a danger that people were over-greasing them and the grease was finding it's way into and restricting the pump filter.
DavidP
 
Whelp, I got it apart. The bushings were so tight I had to cut them off. Are the new ones over sized and you hone them to fit like the spindle bushings? I wonder because someone kinda restored this machine before. I wonder if they were extra tight to begin with. I did pein the end of the shaft. I really had to wail the living sh*t out of it to get it apart. If I had someone to hold my brass it would have turned out better. My amish neighbor has a machine shop, I'm sure he can clean it up for me. Thanks once again for the assistance.
 
Hi, unless someone has bored the cover which is very unlikely standard bushes should be used. The shaft should be a 'loose' fit as there is no requirement for a reamed fit. Whilst not beyond possibility I think it will be very difficult for your neigbhour to 'recover the shaft. The reason for this is that two of the splines are effectively joined together to form a master spline. If this end 'connector' is ground or machined off you may end up with the lift arms and ram arm in the wrong relative alignment with possible major damage ensuing. If a shaft is available it would be the best option. Guessing $45 or so.
I would like to have had someone to hold my drift as well!!!! Hard work without help.
It didn't beat you!
DavidP
 
Hi, unless someone has bored the cover which is very unlikely standard bushes should be used. The shaft should be a 'loose' fit as there is no requirement for a reamed fit. Whilst not beyond possibility I think it will be very difficult for your neigbhour to 'recover the shaft. The reason for this is that two of the splines are effectively joined together to form a master spline. If this end 'connector' is ground or machined off you may end up with the lift arms and ram arm in the wrong relative alignment with possible major damage ensuing. If a shaft is available it would be the best option. Guessing $45 or so.
I would like to have had someone to hold my drift as well!!!! Hard work without help.
It didn't beat you!
DavidP
 

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