Building a backhoe? Anyone ever done it?

[Renze]

If this was in the stabilizer circuit which doesn't cycle often, it is no big deal, but for a swing cylinder that will be actuated constantly, I would be concerned with heat buildup.

I try to baby that swing lever, so it lets oil escape to the return side in the valve block. but sometimes it goes a little fast. only on that occasion i need some restriction. I dont intend to yank the lever to full flow, just need a safety backup next to careful operating.

 

[Yooper75]

I try to baby that swing lever, so it lets oil escape to the return side in the valve block. but sometimes it goes a little fast. only on that occasion i need some restriction. I dont intend to yank the lever to full flow, just need a safety backup next to careful operating.

Why not regulate the fluid with are regulator to slow the swing speed down, all of the hydraulics on our Prentice Telstick33 material handling booms are regulated hydraulics. If you set the regulators correctly you can get very slow and precise movements of the main stick boom/dipper boom functions and swing even when you are running the engine at full power and still be able move the boom at a pretty good clip and not be jerky.

I have run my friends John Deere 310 backhoe and it drives me nuts because of how jerky the swing and boom functions are. I am almost positive the machine does not have regulators of they have been messed with at some point to try and improve hydraulic cylinder speed.

 

[jimgerken]

I wonder what a hydraulic regulator looks like? How does it allow the fine metering? Sounds like a real great addition to a digger.

 

[Yooper75]

I screwed up they are called flow controll valves intstead of regulators. Here is a picture of what they look like.

 

[Iplayfarmer]

I screwed up they are called flow controll valves intstead of regulators. Here is a picture of what they look like.

That valve does the same thing that Renze does with his laser cut washer. It just restricts the flow. The one advantage of the flow control valve is that it can be adjusted in situ.

If you tow it by tractor, you could still operate the stabilisers with tractor hydraulics. But anyways, how often do you turn 360 degree when there is a tow vehicle up front ? If you put the stabiliser lines in a big loop, you could turn 360 degrees too, but just one revolution

The stabilizer operation is a major drawback to the "no-manifold" solution, but at $1450 for a rotary manifold it's easy to justify some compromises. I understand that manual stabilizers are actually fairly convenient on a towable unit. The boom will easily lift the rig enough to drop the stabilizers.

 

[Iplayfarmer]

Dang that's a good idea. I just might implement that into my backhoe. I could have the manual stabilizers, and still just crawl it around, and when I want to turn it from one side to another. I just lift up and use the swing motor to steer it around.

Now I just need to wait until I get some more money to purchase the hydraulic motor, and extra parts. Then I can have my home made mini excavator with 360 swing.

Thanks for the idea.

Chad

You can probably get what you need for the ring gear and pinion by scrapping out a rear axle of some defunct vehicle.

Another thought regarding the swing speed... In my design, I purposely included a larger diameter swing cylinder anticipating that I'd want to slow it down a bit.

 

[Renze]

Why not regulate the fluid with are regulator to slow the swing speed down, all of the hydraulics on our Prentice Telstick33 material handling booms are regulated hydraulics.

At work, the Parker M200 loader valve can set flow and pressure per section... But at home i must keep cost in mind, because i cant make those 15 to 25.000 hours to amortise the expenses...

Any flow controlling device in a system with fixed displacement pumps, will generate heat and waste fuel revving the engine down is the cheapest way to speed down movements...

 

[Yooper75]

At work, the Parker M200 loader valve can set flow and pressure per section... But at home i must keep cost in mind, because i cant make those 15 to 25.000 hours to amortise the expenses...

Any flow controlling device in a system with fixed displacement pumps, will generate heat and waste fuel revving the engine down is the cheapest way to speed down movements...

This is true they are on the pricey side and I completely understand not wanting the added expense to the project. The only thing that concerns me is when you reduce the engine RPM is you loose pressure and put more strain on the pump and engine because it's not running in it's power band trying to do the same work. I have had to use our boom when the high idle switch quit working on me and both the engine and hydraulics worked really hard to move what I was unloading that normally would not even phase the engine or hydraulic pump at 1500 RPM instead of idleing at 600-750 RPM. You could always use the laser cut washers that were mentioned as an less expensive way to regulate the pressure and speed of the swing cylinder.

Listen to the load that get's put on the engine in this video until he up's the idle. There is a reason why excavators and backhoes run at the RPM's they do.

Cub Cadet 149 - YouTube

 

[Renze]

Listen to the load that get's put on the engine in this video until he up's the idle. There is a reason why excavators and backhoes run at the RPM's they do.

Cub Cadet 149 - YouTube

This guy doesnt have his ratios right: The engine too small, the pump too big or the pulley ratio too tall. When i use it on my 3011 i put the gear range lever in neutral, switch the combined PTO/pump drive to ground driven, and put the transmission in 4th gear. That way i get full flow at only 1400 engine rpm. It doesnt even lug the 40hp engine down one bit. Most mini excavators (1 to 1.5 ton) comparable to my Bobcat backhoe have about 18hp.
With the 20 liter of oil in a 1000kg cast rear end, i'm not too worried about heat buildup.

 

[Yooper75]

This guy doesnt have his ratios right: The engine too small, the pump too big or the pulley ratio too tall. When i use it on my 3011 i put the gear range lever in neutral, switch the combined PTO/pump drive to ground driven, and put the transmission in 4th gear. That way i get full flow at only 1400 engine rpm. It doesnt even lug the 40hp engine down one bit. Most mini excavators (1 to 1.5 ton) comparable to my Bobcat backhoe have about 18hp.
With the 20 liter of oil in a 1000kg cast rear end, i'm not too worried about heat buildup.

Sounds like you have a very nice set up, I learned something new today thank's. I am going to get my John Deere 317 project tractor tomorrow and I will be tearing in down in a couple weeks to start a loader/backhoe build of my own over the winter. If you don't mind I may need to pick your brain from time to time.

Dave