Tractor backhoe - homemade

[Luremaker]

Another possibility is to offer the plans and all the parts as a complete do-it yourself kit. Similar to what EA has been talking about doing with their attachments. I would imagine with a well designed backhoe and website you would be able to sell a number of kits every year. I bet there are members here who would be interested in such a kit. I realize this would be a lot more work than simply selling your plans. You'd have to run the numbers and see what would be more profitable plans or kits or maybe both.

 

[BFreaky]

My main goal is to finish this one, and then we will see what comes out of it...

 

[BFreaky]

Here's how it goes... I've disassembled old hydraulic cylinders and checked them inside out. One of the outter parts was in very bad shape so I measured it and made a new one with tripple seals inside. It fitts perfectly and it should be ok now.

These cylinders are now ready for use (afkors, I will put on some new pait on them). The first one (left to right) will be used as a main boom lift cylinder, the second one as a dipper folding cylinder, and the two red ones will be uset for stabilizer legs. The bucket cylinder and the one for hydraulic thumb still need to be checked out.

After fixing them I continued working on some rings and new "heads" for swing cylinders. I will make a trunnion type double acting cylinders to swing the boom assembly.

 

[rScotty]

I will make a trunnion type double acting cylinders to swing the boom assembly.

Have you drawn up a flow diagram for the hydraulics yet? I'm curious about the relief valves and return lines.....are you going to design your own reliefs or go with commercial?
rScotty

 

[kiotiken]

Wow, very, very, very impressive. I love seeing what true machinists are capable of. Keep these posts coming.

 

[BFreaky]

Have you drawn up a flow diagram for the hydraulics yet? I'm curious about the relief valves and return lines.....are you going to design your own reliefs or go with commercial?
rScotty

Well, I think there is no need for a relief valve, the swing cylinders will be connected in X. If we have 2 cylinders who work in tandem, I intend to connect them like this: A1 with B2 and B1 with A2. One is pushing, and the other is pulling in the same time...

 

[rScotty]

Well, I think there is no need for a relief valve, the swing cylinders will be connected in X. If we have 2 cylinders who work in tandem, I intend to connect them like this: A1 with B2 and B1 with A2. One is pushing, and the other is pulling in the same time...

Yes, that will work for simple movements & when only using a single pair of cylinders to move the BH in a single plane. BH flow is complicated because it is normal to power more than one cylinder pair simultaneously so as to make the bucket move in a complex motion rather than a series of orthogonal motions. And most control valves are set up to take advantage of that.
For example, you will probably want to limit the force of the swing cylinders to be lower than the force that you want for the bucket curl motion. As I'm sure you know, this can be done to some extent by using larger or smaller cylinders and mechanical advantage. But since what you have is a combination of second hand cylinder sizes (congrats there, BTW) another way is to limit the pressure of the various circuits with relief valves.

There was a thread where some of this is discussed. You might get some ideas from reading: http://www.tractorbynet.com/forums/kubota-owning-operating/246337-backhoe-swings-right-but-not.html
luck, rScotty

 

[jimgerken]

Please consider adding a quick-change bucket feature to the backhoe. It is really difficult to change buckets by driving out the pins, but easy if you have a quick-change system. It is a natural to want a couple different buckets eventually.

As said, very nice work. It is unusual to find someone as artistic as yourself who is also an accomplished fabricator.

 

[BFreaky]

Yes, that will work for simple movements & when only using a single pair of cylinders to move the BH in a single plane. BH flow is complicated because it is normal to power more than one cylinder pair simultaneously so as to make the bucket move in a complex motion rather than a series of orthogonal motions. And most control valves are set up to take advantage of that.
For example, you will probably want to limit the force of the swing cylinders to be lower than the force that you want for the bucket curl motion. As I'm sure you know, this can be done to some extent by using larger or smaller cylinders and mechanical advantage. But since what you have is a combination of second hand cylinder sizes (congrats there, BTW) another way is to limit the pressure of the various circuits with relief valves.

There was a thread where some of this is discussed. You might get some ideas from reading: http://www.tractorbynet.com/forums/kubota-owning-operating/246337-backhoe-swings-right-but-not.html
luck, rScotty

I understand what you mean. Swing cylinders will have limited flow and pressure just to give them a smooth motion. I was lucky to find the right sizes of used cylinders for every part of my backhoe, although they come from 4 different machines and it took me a while to get them all. Tandem pumps and 2 separate joystick valves are there exactly to avoid these series of orthogonal motions. It is gonna be a dual circuit, so everything should work simultaneusly. Joystick valves have a parallel inner connection, so individual flow can be divided to two commands on one joystick at the same time.

Jimgerken, quick coupling of the bucket is a must, I have bad experiences with front loader bucket changes... It took 2 of us and 15 minutes of hammering, every time!
I did not like that so I solt the original bucket, built a new one and made it like this:

It works much better then the original, it's bigger and heavy duty, and the coupling takes like 1 minute.

 

[kiotiken]

Man, I'm almost starting to wonder why you even bothered buying a tractor, seems like you could have just built a much better one from scratch! Very impressive work, you have serious skill and ingenuity.