L785 slow boom and bucket. Aux hydraulic ?

Mike10 · Dec 23, 2017

JWD said:
OK. I removed the hose from the flow control valve to the aux. valve and plugged the fitting at the aux. valve. started the engine and nothing came out at all. I removed the hose from the distribution block that comes from pump outlet #2 in my diagram and the hose from the tee on the distribution block that runs to the boom/bucket control valve and air blows through freely.

It appears you do not have flow from the pump to the distribution block. Did you remove the cap to the strainer and see if there is any oil in the tube. Did you check the oil level

JWD · Dec 23, 2017

Mike10 said:
It appears you do not have flow from the pump to the distribution block. Did you remove the cap to the strainer and see if there is any oil in the tube. Did you check the oil level

overall oil level is right on the full mark. under seat strainer the tube is completely full the floor boards strainer tube was about 1/2 to 2/3 full.

JWD · Dec 26, 2017

JWD said:
overall oil level is right on the full mark. under seat strainer the tube is completely full the floor boards strainer tube was about 1/2 to 2/3 full.

With the hose from pump outlet number 2 removed at the distribution block I cranked the engine and just got a small push of oil with each revolution of the engine. I would say it was probably 1/2 a measuring cup per revolution. Would you agree it's time to remove the pump for inspection?

JWD · Jan 1, 2018

JWD said:
With the hose from pump outlet number 2 removed at the distribution block I cranked the engine and just got a small push of oil with each revolution of the engine. I would say it was probably 1/2 a measuring cup per revolution. Would you agree it's time to remove the pump for inspection?

I got the pump off today and started cleaning it up externally. I'm gonna open it up and have a look at the inside one night this week. I haven't found any brand or part numbers on this double pump yet. I did find where I can order the single pump for about $400.

JWD · Jan 2, 2018

JWD said:
I got the pump off today and started cleaning it up externally. I'm gonna open it up and have a look at the inside one night this week. I haven't found any brand or part numbers on this double pump yet. I did find where I can order the single pump for about $400.

JWD · Jan 2, 2018

JWD · Jan 2, 2018

JWD · Jan 2, 2018

the surface at the top of the picture with the arrow pointing towards it from the right is the discharge side and is very rough almost has a fine sandpaper feel to it. the surface at the bottom of the picture with the arrow pointing towards it from the left looks somewhat worn but is very smooth. In the next picture the the copper colored part that the ends of the gears run against shows visible signs of wear and towards the bottom right has heavier wear that can be felt when dragging my finger nail across it.

JWD · Jan 2, 2018

JWD said:
the surface at the top of the picture with the arrow pointing towards it from the right is the discharge side and is very rough almost has a fine sandpaper feel to it. the surface at the bottom of the picture with the arrow pointing towards it from the left looks somewhat worn but is very smooth. In the next picture the the copper colored part that the ends of the gears run against shows visible signs of wear and towards the bottom right has heavier wear that can be felt when dragging my finger nail across it.

JWD · Jan 2, 2018

JWD · Jan 3, 2018

Mike10 said:
It appears you do not have flow from the pump to the distribution block. Did you remove the cap to the strainer and see if there is any oil in the tube. Did you check the oil level

Does this look like the correct way to hook things up using a oem single inlet single outlet pump?

JWD · Jan 3, 2018

JWD said:
Does this look like the correct way to hook things up using a oem single inlet single outlet pump?

I'm unclear on what the small box on the side of the control valve "P.B." is meant to represent.

Ivan · Jan 3, 2018

JWD said:
I'm unclear on what the small box on the side of the control valve "P.B." is meant to represent.

P B usually means power beyond

JWD · Jan 4, 2018

Ivan said:
P B usually means power beyond

Thanks. Could any of you guys tell me if the power beyond is a separate port off the side of the control valve? From what I gather there is a special fitting that goes in the side of the control valve. Mine has a plug on the side. I didn't see any picture or reference of this in my parts manual but did read about it on a forum called haytalk.

Mike10 · Jan 7, 2018

JWD said:
Thanks. Could any of you guys tell me if the power beyond is a separate port off the side of the control valve? From what I gather there is a special fitting that goes in the side of the control valve. Mine has a plug on the side. I didn't see any picture or reference of this in my parts manual but did read about it on a forum called haytalk.

There are three ports on the control valve other then the bucket and boom ports. One is the "in" port, one is the "out" port and one is the "power beyond port". The purpose of the power beyond port is to supply pressureized oil to the aux valve. The way it works is like this, oil is supplyied to the control valve through the in port. From there it will go to the boom or bucket ports if the pedals are pushed. If no pedal is pushed the oil then flows through the power beyond port tot he aux valve........If a pedal is pushed then oil will be supplied to one of the ports of a cylinder. Since there is oil on both sides of the cylinder oil must be exhausted from the opposite port of the cylinder. This exhasuted oil returns to the oil cooler and filters and eventually to sump.....To determine which of the two out ports is the power beyond, if not cast into the valve housing, remove the fitting from the valve. Under the treads of the removed fitting, a power beyond port will have a machined tube or a cylindrical bore to a port inside the valve body..... An out port will expand to the galley of the valve body under the threaded portion of the valve......The way it should work is oil flows to the control valve to the aux valve through the power beyond port. On the aux valve there are only an in and out port so the out flow of oil goes to the the cooler and filters. This flow is tee'd into the out flow of the control valve......The diagrams both yours and NHs have too many lines. The NH diagram shows all possible configurations with added options. Your setup should be simple. From the hyd pump oil goes to the control valve. Oil goes through the control valve to the aux valve via the power beyond port. The out flow from the aux valve is tee'e into the outflow of the control valve and returns to the cooler and filters and sump....Why power beyond? You could use the out flow from the control valve to supply oil to the aux valve and everything would work ok until you were using both valves at the same time. Say you are raising the boom. Not all oil is going to raise the boom some is being sent through the valve and in or theoretical situation the rest of the oil is going to the aux valve from the out port. Now while raising the boom you activate the aux valve so the pressure from the hyd pump is raised farther, you are causing the oil being exhausted from the boom cylinder to raise to a point where some weird things can happen, such as the boom actually lowering. Basically you are supplying oil to both sides of the boom cylinder. Pressure coming in from the pump and back pressure building in the out port from the requirements of the aux valve. Since in a properly plumbed system there is no substantial back pressure the system works since no pressuize is being built on the out side of the valve.

JWD · Jan 7, 2018

Mike10 said:
There are three ports on the control valve other then the bucket and boom ports. One is the "in" port, one is the "out" port and one is the "power beyond port". The purpose of the power beyond port is to supply pressureized oil to the aux valve. The way it works is like this, oil is supplyied to the control valve through the in port. From there it will go to the boom or bucket ports if the pedals are pushed. If no pedal is pushed the oil then flows through the power beyond port tot he aux valve........If a pedal is pushed then oil will be supplied to one of the ports of a cylinder. Since there is oil on both sides of the cylinder oil must be exhausted from the opposite port of the cylinder. This exhasuted oil returns to the oil cooler and filters and eventually to sump.....To determine which of the two out ports is the power beyond, if not cast into the valve housing, remove the fitting from the valve. Under the treads of the removed fitting, a power beyond port will have a machined tube or a cylindrical bore to a port inside the valve body..... An out port will expand to the galley of the valve body under the threaded portion of the valve......The way it should work is oil flows to the control valve to the aux valve through the power beyond port. On the aux valve there are only an in and out port so the out flow of oil goes to the the cooler and filters. This flow is tee'd into the out flow of the control valve......The diagrams both yours and NHs have too many lines. The NH diagram shows all possible configurations with added options. Your setup should be simple. From the hyd pump oil goes to the control valve. Oil goes through the control valve to the aux valve via the power beyond port. The out flow from the aux valve is tee'e into the outflow of the control valve and returns to the cooler and filters and sump....Why power beyond? You could use the out flow from the control valve to supply oil to the aux valve and everything would work ok until you were using both valves at the same time. Say you are raising the boom. Not all oil is going to raise the boom some is being sent through the valve and in or theoretical situation the rest of the oil is going to the aux valve from the out port. Now while raising the boom you activate the aux valve so the pressure from the hyd pump is raised farther, you are causing the oil being exhausted from the boom cylinder to raise to a point where some weird things can happen, such as the boom actually lowering. Basically you are supplying oil to both sides of the boom cylinder. Pressure coming in from the pump and back pressure building in the out port from the requirements of the aux valve. Since in a properly plumbed system there is no substantial back pressure the system works since no pressuize is being built on the out side of the valve.

Thanks Mike10 here's what my control valve looks like. should I be looking for the power beyond port under one of these two plugs in the middle they are neither one marked? I'm of the understanding from your last post that it would be unadvised to use the out flow of the control valve to supply the aux valve. I currently have no use for the aux hydraulics as I only intend to use the loader at this time but I would prefer to have it available as an option for the future since the machine already has the aux control valve and controls in place.

Mike10 · Jan 7, 2018

JWD said:
Thanks Mike10 here's what my control valve looks like. should I be looking for the power beyond port under one of these two plugs in the middle they are neither one marked? I'm of the understanding from your last post that it would be unadvised to use the out flow of the control valve to supply the aux valve. I currently have no use for the aux hydraulics as I only intend to use the loader at this time but I would prefer to have it available as an option for the future since the machine already has the aux control valve and controls in place.

The valve looks like it has been replaced. The two plugs in the center are load check valves. Is there another port in the valve with a plug. It would be the same size as the in and out ports.

JWD · Jan 7, 2018

Mike10 said:
The valve looks like it has been replaced. The two plugs in the center are load check valves. Is there another port in the valve with a plug. It would be the same size as the in and out ports.

only other plug I can find is this one on the side of the valve. This is the side closest to the out port. It looks like its the same size as the in and out ports that are on the front of the valve.

JWD · Jan 7, 2018

JWD said:
only other plug I can find is this one on the side of the valve. This is the side closest to the out port. It looks like its the same size as the in and out ports that are on the front of the valve.

It's probably not relavent at this point but I thought I'd show a picture of what I was calling the distribution block earlier.

JWD · Jan 7, 2018

JWD said:
It's probably not relavent at this point but I thought I'd show a picture of what I was calling the distribution block earlier.

my pictures where too big before and they seem to be getting bigger. I apologize. I'm not sure how to fix it.

L785 slow boom and bucket. Aux hydraulic ?

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