Stand alone hydraulics on a log loader

[rasorbackq]

Here again for another lesson in hydraulics... My log loader has a gas engine and a hydraulic system. Unsure of the motor HP . The other day I was using the loader and lost all power Could just swing the boom left and right open and close the clam. Anything that required lifting didn't work. The few functions that did work were very very slow to do it. I looked in reservoir. It was very low (cal in empty), . Not sure how it lost all the fluid but I haven't looked in there for a long time.

hose on left is the lowest hose from tank.Straight line is to valve bank notice the arrow direction!!

We disconnected the hose into the valve bank from the pump. Started the motor and it had flow. Not a lot of flow but some . So thinking I burned the pump out I changed the pump. Again unsure of the original pump capacity I got a pump from a friend . This pump was definitely more volume. He thought 16 gal per minute. This was a used pump he said worked . After all plumbed in no functions work on the loader. Not even any flow from the pump out hose to the valve bank. . The only difference we had was the arrow on the pump. Original the arrow point to the left standing in the front looking at motor and facing down. The replacement was on top looking right. Does the arrow mean flow direction????

With each of the two other pumps ( one brand new never used) installed we attached the lowest hose on the tank to the arrowed port. Then we switched the hoses and still didn't work. No functions work on the loader.. When I was buying fittings the guy said he didn't think the pump was pooched but it was airlocked. Said to crack the fitting and unsure cylinders were getting fluid. We did that to a couple functions and fluid came out the loose connection but no air. Not a lot of fluid but no pressure.

What does the arrow mean??? Flow direction or engine rotation?
Couple questions based on the pics... The hydraulic feed to pump should be which hose .....the lowest one on the tank or the one with the filter?

Must be missing something??
Can this system be air locked??
Can any one guess the volume flow for the original.

 

[LD1]

The arrows are pump rotation. Must match the motor.

I am unsure of your description and pictures whether the new pump is opposite of the old one.

The lowest hose is likely the suction hose going to pump inlet. The hose with the filter is likely the return hose....it should be coming from the outlet or tank port of your valve bank

 

[LD1]

The pump in the second pic looks like a CW pump rotation when looking at the shaft.

The other pics....appear to maybe be CCW pumps? Hard to tell cause I cannot see the whole pump and which end is the shaft end.

You are there and can verify....if they indeed are opposite rotation directions....sadly there is no remedy other than buying a new pump. That or some creative use of belts/pulleys and remount the pump

 

[rasorbackq]

All the pumps are CW operation.

The original pump is a clock wise like the arrow but the gears roll outwards so the oil can travel around the outside of the pump case to the outlet port.
The 2 I put in are clock wide rotation but the internal gear roll inwards and there is no room for oil between the teeth of the gears .
. After looking at the net . All these pumps can be reversed to be clockwise rotation and an outward rolling gear set up. So that's what I did . had to take apart all 3 pumps to finally get one back together right. Now I can see fluid movement in the tank but as soon as any valve is just touched it kills the engine. Pumps are to much for the engine.

 

[ptsg]

Going by the numbers on the pump on the first picture of the first post (the original one?), it is a 6.28 CC group 2 gear pump. If the pump is indeed bad, you'll need to find something on that size to replace with otherwise, anything bigger will kill the engine as you experienced.

 

[rasorbackq]

\HOW DO YOU KNOW THAT ?
I cant google that # at all

 

[rasorbackq]

6.28 CC group is that 6 gallon per minute

 

[rasorbackq]

Looking for info . Thinking my engines a 6hp . What size pump will it handle

 

[ptsg]

The numbers are very similar across different manufacturers of these gear pumps, so that sounded familiar to me. Anyways, here is the link to a bit more info. About half of the number matches, the rest not so much because there may have been some changes done over the years. https://timalco.com.au/wp-content/uploads/2020/12/pz2cg06-splined-shaft.pdf

6.28 CC (cubic centimeters) or about 0.38 ci (cubic inches) is the displacement of the pump. These are the numbers that matters, when buying a replacement pump, along with max pressure as there are some pumps out there that have relatively low max pressure ratings. The flow (GPM) depends on what RPM the pump is running.

This pump puts out about 4.14 GPM at 2500 RPM, just as an example. The same pump will put out 4.9 GPM at 3000 RPM.

I don't know the system pressure on that log loader though, but I don't see it being more than 2600 PSI.

 

[rasorbackq]

Ok thanks. have to go on your math and #s. There is a 4.2 gallon pump that seems to be the right one.