BH 75 hose replacement

[nspec]

Hello all. BH 75 backhoe with a hose that's pretty badly chafed - bet you'll never guess which one? Yeah, it's the one for the boom cylinder that droops down and rubs on the backhoe swivel. Anyway, I realize I have to remove the boom cylinder to get the hose off, and I'm looking for advice from someone who has done this.

Here's my plan with my questions:

I was going to swing boom to a 90 deg. angle and lower all the way to the ground so I can pull the cylinder out freely. Do I need to get the boom lower? What I mean is do I need a negative angle? Should I dig a hole to lower the boom into, or tilt the tractor up to get the boom even lower, or is lowering it to the ground normally going to be enough?

Next move would be to drive the pins out that attach the boom cylinder. Anything unusual to expect here? What do people use to drive the pins out?

Then I guess the cylinder comes out of the boom and it's pretty easy from there. Should I worry about the cylinder catching on the other hoses inside the boom on removal or reinstall? Lose much oil if you relieve the pressure?

And yes, I plan on adding chafe protection to the new hose if not making it a little shorter so it doesn't rub on the pivot. Man, what a dumb design hiding the hoses in the boom. They should be hard piped in the boom with fittings and a transition to hoses in the open at each end. What would it cost, just a little more?

Anyway, whatever advice you guys could give me would be a huge help. Doesn't sound hard, just want to be prepared. Thanks!

 

[leonz]

Hello all. BH 75 backhoe with a hose that's pretty badly chafed - bet you'll never guess which one? Yeah, it's the one for the boom cylinder that droops down and rubs on the backhoe swivel. Anyway, I realize I have to remove the boom cylinder to get the hose off, and I'm looking for advice from someone who has done this.

Here's my plan with my questions:

I was going to swing boom to a 90 deg. angle and lower all the way to the ground so I can pull the cylinder out freely. Do I need to get the boom lower? What I mean is do I need a negative angle? Should I dig a hole to lower the boom into, or tilt the tractor up to get the boom even lower, or is lowering it to the ground normally going to be enough?

Next move would be to drive the pins out that attach the boom cylinder. Anything unusual to expect here? What do people use to drive the pins out?

Then I guess the cylinder comes out of the boom and it's pretty easy from there. Should I worry about the cylinder catching on the other hoses inside the boom on removal or reinstall? Lose much oil if you relieve the pressure?

And yes, I plan on adding chafe protection to the new hose if not making it a little shorter so it doesn't rub on the pivot. Man, what a dumb design hiding the hoses in the boom. They should be hard piped in the boom with fittings and a transition to hoses in the open at each end. What would it cost, just a little more?






Anyway, whatever advice you guys could give me would be a huge help. Doesn't sound hard, just want to be prepared. Thanks!

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About your backhoe;

Please dont shorten the hose as it will become too short and pull out of the

fitting sockets.



1. ON FLAT FIRM GROUND fully extend the bucket by retracting the cylinder until it stops.


2. fully extend the dipper boom to its maximum (all the way out)


3. place some hardwood blocking under the upper boom; you will

want to crib it in the middle of the main booms length prior to

lowering the main boom on the cribbing.


4. after you lower the upper boom, shut the tractor off be sure to relieve all

the pressure in the backhoe before you remove the hose, be sure to have

a drip pan for the oil and be sure to have a rag handy to cover the

connection if it spurts.


5. lower the upper boom until it stops then relieve the system pressure then

break the connection and purchase a new hose PLUS a length of abrasion

sleeve to install over the new hose.


The hoses are better protected in the upper booms main tube but they did

not add abrasion prevention sleeves which would have reduced the issue to a

minimum.



About the cylinder pins; and after you have lowered the upper and dipper

booms on the ground and wooden cribbing-



The pins will be secured with bolts or roll pins that must be removed first.

Use a roll pin punch sized for roll pins-if used. Be sure to purchase new spring roll pins to replace the original ones. use a small pair of vice grips to compress the new roll spring pins before starting them in the holes. when the roll pin is in about 3/8's of an inch you can safely use the roll pin punch to install the new roll pins.


use a bronze drift pin to drive the cylinder pins out not a steel punch!!!

You can cheat and use a CO2 fire extinguisher to shrink the pins and make

the removal easier.


Place the pins in the freezer until its time to put them back in again.

 

[nspec]

Thanks for the advice. Sounds good, however I'm looking for some advice specific to this model backhoe. It's a Kubota BH75, which can fit the Kubota B2630, B3030, L2800, L3400, L3240 and L3540.

There is no way to remove the cylinder if the boom is up on cribbing - the cylinder needs to slide out the bottom of the boom. As the boom is lowered, it moves away from the swing mechanism allowing more room. At the very least, the boom needs to be lowered down on the ground to allow for clearance and proper angles. This also extends the cylinder. Once the bottom pin is removed, the cylinder can be retracted, top pin removed, and hopefully the whole thing just comes out. I was thinking in fact that it needed to get below horizontal, hence my idea with the hole. The cylinder HAS to be removed to access the hoses - they are way up inside the boom. They are not specially reinforced, but are the same hoses found throughout the tractor. My chafed hose was not inside the boom - it is on the outside and plainly visible. The ones inside you could never see until it was too late. Very poor planning.

Bronze drift...got it.

Pins in the freezer - you read my mind!

Thanks!

 

[art]

For many a boom having the hoses inside saves many hose from being damaged.

 

[rbminmn]

I replaced this hose on a BH75 this summer. The advise Leonz provided is all correct. On level ground get the boom and dipper stick both about horizontal and supported by the bucket and cribbing under the boom. The pins came out and went in easily (I used a round wooden dowell) without any cooling. The big difficulty is getting the upper end of the cylinder high enough in the boom to get the pin back into it. I wound up using the dipper stick to raise the boom until I could insert a small pry bar into the boom at the boom/dipper stick joint and using the pry bar to raise the cylinder end up so the pin holes would align. You don't really have to apply much force to the pry bar; you just need a way to raise the upper end of the cylinder in the boom.

 

[nspec]

Thank you. That's exactly what I was looking for.

Happy Thanksgiving!