Backhoe Pump Deadheaded???

[elkmtngear]

How does your hydraulic pump mount?

Here's a re-oriented pic (labelled). The pump bolts to the tractor above the regular PTO shaft, and has a slotted adaptor that joins the shaft to the pump.



This is the type of interface on the back of the pump:



The PTO lever has 2 speeds (540 and 720). Posthole Digger was run at 540.



I'll go through the Jinma Threads, thanks for the tip!

 

[ericm979]

Could you show us where the pump fit on the tractor?

The usual PTO pumps have a hollow splined port where the typical 6 spline PTO stub fits. The pump is sealed as is the PTO stub on the tractor. There's no way oil from the pump can get in the tractor unless seals on both the pump and the PTO stub are totally missing and even then most of the oil would end up on the ground. Your pump looks very different. It may be special for jinma. This may be why people are confused, we all assumed you had the typical pump.

Typical PTO pump: 3.41 cu in 7.4 GPM 54 RPM Dynamic GP-PTO-A-3-6-S Hydraulic PTO Pump | Dynamic | Brands | www.surpluscenter.com

 

[elkmtngear]

Your pump looks very different. It may be special for jinma.[/url]

Yes, apparently it's unusual. I called Circle G Tractors, and they were not too surprised. Apparently I need to rebuild the pump, there are several seals in it that can fail. Ordering a rebuild kit.

 

[dfkrug]

The pump is sealed as is the PTO stub on the tractor. There's no way oil from the pump can get in the tractor unless seals on both the pump and the PTO stub are totally missing and even then most of the oil would end up on the ground. Your pump looks very different. It may be special for jinma. This may be why people are confused, we all assumed you had the typical pump.

That Jinma is indeed very unusual. Like you, I do not see how oil would get from the failed pump into the tractor sump. TWO seals would have to fail, I would think.

Note that Deere x55 tractors also put their implement pumps hanging off the back, right above the normal PTO shaft.

 

[oldnslo]

Elkmtn
Looking at the picture of the pump it is clockwise rotation as viewed looking at the tang on the drive shaft. Which way does the PTO spin on your tractor

I.e. while looking at rear of tractor where the pump mounts it would be counterclockwise

 

[elkmtngear]

elkmtn,
Where is the pump inlet hose connected for the back hoe pump? If connected to a reservoir on the back hoe then all of the lines on the back hoe should remain connected to the hoe. If one is the the hoe and the other to the tractor you will over fill one reservoir and drain the other.

If connected to the sump or reservoir on the tractor then the return or tank line from the back hoe must also be connected to the tractor sump preferably below oil level and as far away as possible from the pump inlet.

Returning oil above the oil level can cause foaming and aerate the oil.

Another potential problem is the back hoe pump flow rate vs the sump size of your tractor. To much flow rate can also cause aeration - foaming of the oil.

Both the inlet and outlet hoses are connected to the backhoe only. The backhoe tank was full to the dipstick mark when I started, but now is very low. I'm certain that oil was being pushed into the tractor through the shaft seal on the pump.

 

[elkmtngear]

Elkmtn
Looking at the picture of the pump it is clockwise rotation as viewed looking at the tang on the drive shaft. Which way does the PTO spin on your tractor

I.e. while looking at rear of tractor where the pump mounts it would be counterclockwise

I was told by the Circle G parts guy, that the upper tang shaft where the pump mounts, goes the opposite direction of the PTO shaft. The hydraulic pump was supposed to be designed for that, but who knows? I need to check it thoroughly after I kit it.

 

[rScotty]

Knowing which way the tang is turning will probably tell you which of the hoses is feed and which is pressure. You will confirm that when you kit it & actually see the internal gears. The way that the tang is off-center on the pump makes it a sure bet that you have a typical spur gear type hydraulic pump. So find the direction of rotation of the tang, then study this link and you will see how to tell which hose is your pressure hose to the BH controls and which is inlet supply. Note that the oil flows around the outside of the gears... carried by the space ibetween the gear teeth and case. Oil is NOT squeezed between the gear teeth to any great or effective amount..
Hydraulic Spur Gear Pump | Hydraulic Pump

I'm not surprised that the upper tang turns reverse of the PTO - all that means is that tang and PTO are geared together without an idler gear in between. That makes for less parts, easier to design, and enables the PTO clutch or actuation to work both systems.

It actually looks like a pretty good system. Nice machining, nice pump casing, decent bolt pattern. Is the rest of the tractor as good?
rScotty

 

[elkmtngear]

Knowing which way the tang is turning will probably tell you which of the hoses is feed and which is pressure. You will confirm that when you kit it & actually see the internal gears. The way that the tang is off-center on the pump makes it a sure bet that you have a typical spur gear type hydraulic pump. So find the direction of rotation of the tang, then study this link and you will see how to tell which hose is your pressure hose to the BH controls and which is inlet supply. Note that the oil flows around the outside of the gears... carried by the space ibetween the gear teeth and case. Oil is NOT squeezed between the gear teeth to any great or effective amount..
Hydraulic Spur Gear Pump | Hydraulic Pump

I'm not surprised that the upper tang turns reverse of the PTO - all that means is that tang and PTO are geared together without an idler gear in between. That makes for less parts, easier to design, and enables the PTO clutch or actuation to work both systems.

It actually looks like a pretty good system. Nice machining, nice pump casing, decent bolt pattern. Is the rest of the tractor as good?
rScotty

Great link, exactly what I needed. Thank You.


So far, the only problem I've had with the tractor, was a broken steering knuckle on the front, which I had to replace. The FEL is a beast, I've cleared a bunch of manzanita with it. I've been itching to get this backhoe working, so I could play around with it.