kubota b7800, bh75 hoe, adding hyd thumb

[garthr]

hi ive added a hyd thumb to the hoe. teed into the p and t lines to supply a 1 spool valve. now hoe controls very sluggish, also thumb. when hoe controls and thumb operated at the same time, speed of all is normal. 1. did i pipe correctly and 2. when the added spool valve is in neutral is it allowing p to leak into t line internally? way to plug this off or change piping routing?

 

[Big Chief]

Did you use a valve that has power beyond PB ? If you just added a standard valve in series it will not work.
Show us some pics of what you did

 

[RNeumann]

Just tee-ing into lines isn’t how hydraulics work. You will need to study up on the Power Beyond concept

 

[Big Chief]

Without using the power beyond valve what happens is the pressure from the hydraulic pump is going to go through the path of least resistance.
So when you try to operate the thumb or the hoe separately most of the pressure will not go to that particular hydraulic ram it will just get bypassed through the other valve that you installed and get diverted back to the tank via the return.

When you use them simultaneously the return lines are basically blocked off and the pressure goes to the ram first but you will still have less hydraulic pressure to both.

The power beyond design allows the hoe and the thumb to operate independent of each other and they will not take pressure away from each other as they do now.

Search the forms it sounds complicated but it's a really easy set up

 

[garthr]

Did you use a valve that has power beyond PB ? If you just added a standard valve in series it will not work.
Show us some pics of what you did

heres some photos

 

[3Lfarms]

I cant tell whether that is the right valve, but I know that using steel pipe and steel pipe fittings is a no-no. Those are not rated to hold thousands of pounds of pressure.
Get the correct hydraulic fittings, like the ones that come out of the sides of the valve in the second pic. If a hose doesnt reach, have a longer one made. You or someone you love may loose an appendage because you cheeped out and used those pipe fittings.

 

[Redlands Okie]

Very good warning on the use of proper fittings. Also be very careful if your using teflon tape on the fittings. Have read some horror stories of people letting just a tiny tiny tiny little piece of tape get into the hydraulic system.

 

[garthr]

any suggestions on a correct valve 4 this? the valve i have is 4 port open center.

 

[Big Chief]

This is what I used

Power Beyond/Closed Center Sleeve WVS Valves | Prince Mfg | Brands | www.surpluscenter.com

1 Spool 14 GPM Prince WVS11B5C1 DA Valve | Prince Mfg | Brands | www.surpluscenter.com

 

[garthr]

rating for sched 40 steel 1/2" is working 1300, burst 10380. rating goes up as size decreases. of course sched 80 would have a higher rating