3-Point Hitch Challenged to remove pin - Kubota L3540 Lift Arm

[Dave M7040]

A side question - what痴 the engineering rationale for this pin to be effectively 斗ocked into place without any rotation or movement?

The interference fit is a common engineering design when you want the end result to be no relative movement between the parts under load.

Quoting from another source:

Interference fit is the type of fit in which the minimum diameter of the shaft should always greater than the maximum size of the hole. This type of fit between the shaft and hole will give the permanent type of fit and can be used as a solid component.

Another example is the ring gear on an engine's flywheel. Before modern engines, the ring gear was heated, slipped over the flywheel and allowed to contract thus making a never budge fit.

Wood wagon wheels had iron rims. The iron rims were heated so they expanded, slipped over the wood wheel and again allowed to contract.

Ball or roller bearings are often assembled with an interference fit on a shaft. This to ensure that the inner diameter of the bearing does not rotate on the shaft causing wear but rather the rotation happens in the balls as designed.

I suspect the 3 pt hitch pin has an imperceptible taper to allow it to enter its hole and then be forced in as the nut is tightened. Alternatively, the arm would have a slight taper.

Dave M7040

 

[PandDLong]

Thanks Dave - a very informative answer.

I will get a new pin as a first step to make sure my new arm is right sized and to understand the taper situation (I will ask at the dealer when I am there).

I need to make sure to make sure I have the talent to remove and replace before going any further.

I did a quick measure on the width of the lift arm that sits on the pin and the new one is 5/16” narrower. Is that a cause for concern? Should I try to find a bushing/washers to compensate?

So many questions....

Michael

 

[Dave M7040]

Thanks Dave - a very informative answer.

I will get a new pin as a first step to make sure my new arm is right sized and to understand the taper situation (I will ask at the dealer when I am there).

I need to make sure to make sure I have the talent to remove and replace before going any further.

I did a quick measure on the width of the lift arm that sits on the pin and the new one is 5/16” narrower. Is that a cause for concern? Should I try to find a bushing/washers to compensate?

So many questions....

Michael

Don't underestimate your ability to get the pin out. Right tool is all that is needed and then you will be surprised how easy it comes out.

You are referring to the new hydraulic lift link as far as the width is concerned. You could always drill a small hole in the new pin for a spring clip to go through to keep the new link close to the lift arm. Washers too will do this. Better a little loose than too tight a fit.

Order this puller from Amazon for $27.
https://www.amazon.com/Adjustable-Bearing-Puller-Remover-Straight/dp/B06ZZMG8QV?ref_=fsclp_pl_dp_1

If when you receive it, it will not work for you just return it.

You will spend more having the dealer come

Dave M7040

 

[BufordBoone]

I ran into a similar problem. See this thread: https://www.tractorbynet.com/forums/owning-operating/404133-removing-lift-arm.html?highlight=

Short version, penetrating oil and use of an adjustable wrench to rotate the pin. Spent lots of time moving it up and down. Finally got it free.

Edited to add that I put the nuts on the end and hammered (light tapping) on them so as not to damage the threads.

Also, if I remember correctly, it was lots easier to twist the pin down than up because I didn't have an implement on the arms. Twisting up simply lifted the lift arms.

Good luck.

 

[Dave M7040]

An additional technique to try before the puller.

My reluctance to using a hammer is because of the damage you might do to the lift arm shaft which supports the lift arm.

However, if you hold the head of a sledge hammer against the lift arm while you hit the end of the pin (sledge on opposite side where you hammer) the weight and inertia of the sledge head will resist forces being transferred to the lift arm support.

Dave M7040

 

[PandDLong]

Gave it another shot today with the tools I had.

C-clamp won’t fit as my tractor is too narrow - ROPS on one side, the other lift arm on the other.

More Kroil and some tapping/twisting didn’t budge it (I might end up with a “rounded drain plug” scenario as that pin has very little flat edge to grip to start with).

The Pitman arm pullers I’ve looked at won’t be able to grab the lift arm as the anchor point as the pullers are too narrow to get around it.

I’ll work the hammering a bit more aggressively and place a sledge head as a dead weight behind the lift arm as suggested.

What went in should come out - without collateral damage I hope...

 

[BufordBoone]

When I had my issue, it would only move a little each way with a wrench on the flats. I spend considerable time moving it up and down whatever little bit it would move. It got progressively more movement and, finally gave way.

Once out, I polished it with some oil and a rag. Did the same to the hole it came out of. Moved easily thereafter.

I have plans to put some "neverseize" on it so as to avoid the issue in the future.

FYI, I probably spent 2 hours on getting it out. Hope you have success.

 

[PandDLong]

Aha - I will need those common yet elusive tools in my toolbox for this task - time and patience. I will tackle it again when I have those two items in-hand

 

[Dave M7040]

When I had my issue, it would only move a little each way with a wrench on the flats. I spend considerable time moving it up and down whatever little bit it would move. It got progressively more movement and, finally gave way.

Once out, I polished it with some oil and a rag. Did the same to the hole it came out of. Moved easily thereafter.

I have plans to put some "neverseize" on it so as to avoid the issue in the future.

FYI, I probably spent 2 hours on getting it out. Hope you have success.

What you do not want to do is to defeat the design of an interference fit.

An alternative approach would be to grind the head smooth with the shank, drill the pin for a big spring clip and never remove the pin.

Dave M7040

 

[BufordBoone]

What you do not want to do is to defeat the design of an interference fit.

Dave M7040

Well, the first few times I switched out my backhoe, I pulled those pins off with ease. It was only after a few years of not removing them that I'd have called them "interference fit".

I figure that them moving easily for the first couple of years meant they were supposed to move easily.

Does the shop manual call it an "interference fit" (I don't have the shop manual).