Auxiallry Hydraulics Setup Questions

[Nautiluscont]

I am in the progress on installing auxiliary hydraulics on my 48 Cub to control the front blade angle using a bypass block setup... I have read the many posts on here regarding the setup and have a couple of questions:

1) Should the return line from the new spool valve (T port) with an open center be connected to the 1/4 NPT port on the bypass block or plumbed into the TC tank thru the fill port? My particular spool valve has both a T port and a PB (power beyond) port. Reason for asking is it after reading the many posts on here, some say that the (T) line should be plumbed to the TC tank fill and another line ran from the PB (power beyond) port to the return port on the bypass block. Which is correct? I guess more specifically, what is the difference between using the PB port or the T port with an open center? I thought I read somewhere that it has to do with the fact both the TC and new spool both have relief valves and plumbing it straight from the T port the bypass block port puts them in series which could over pressure the system. Is this true? Will the system work effectively and safely with out using the PB port on the new spool? My intent would be to be able to operate the angle control and the TC control but not at the same time if that makes a difference.

2) If an additional return line is need from the T port on the new spool to the TC tank fill plug, how do you fill the system with it plumbed to the TC fill plug opening? My fill plug seems to be an odd size thread but I'm sure I could drill and tap a fitting into it?

Thanks in advance,

[Gary S.]

I did one quite awhile ago and just followed what others here told me. What little I learned I have forgot and at this point the tractor is 1500 miles away. I do have these 2 pictures maybe they will help- sorry about the quality. I had used a "cessna"? valve and TM's block plate at the tc control.

[Cubfriend]

I am in the progress on installing auxiliary hydraulics on my 48 Cub to control the front blade angle using a bypass block setup... I have read the many posts on here regarding the setup and have a couple of questions:

1) Should the return line from the new spool valve (T port) with an open center be connected to the 1/4 NPT port on the bypass block or plumbed into the TC tank thru the fill port? My particular spool valve has both a T port and a PB (power beyond) port. Reason for asking is it after reading the many posts on here, some say that the (T) line should be plumbed to the TC tank fill and another line ran from the PB (power beyond) port to the return port on the bypass block. Which is correct? I guess more specifically, what is the difference between using the PB port or the T port with an open center? I thought I read somewhere that it has to do with the fact both the TC and new spool both have relief valves and plumbing it straight from the T port the bypass block port puts them in series which could over pressure the system. Is this true? Will the system work effectively and safely with out using the PB port on the new spool? My intent would be to be able to operate the angle control and the TC control but not at the same time if that makes a difference.

2) If an additional return line is need from the T port on the new spool to the TC tank fill plug, how do you fill the system with it plumbed to the TC fill plug opening? My fill plug seems to be an odd size thread but I'm sure I could drill and tap a fitting into it?

Thanks in advance,

If I recall correctly that fill plug is 7/8 x 18tpi unless you have the early hydraulic block that is a pipe plug.

[ricky racer]

The pressure from the Cub's pump, bypasses the TC unit and is diverted to your auxiliary valve (P port), hence the name bypass block. The fluid then passes through the open center spool of your auxiliary valve and heads back (from the T port)to the bypass block to continue (as pressure) through the TC unit supplying the TC unit with pressure to operate. That completes the hydraulic circuit. The A & B ports send pressure to your auxiliary cylinder on your blade.
Your auxiliary valve needs to have a pressure relief that can be adjusted down to about 1500 psi so the pressure doesn't dead head when the cylinders fully extend or retract. Your auxiliary valve is upstream of the Cubs relief so the circuit is unprotected without the auxiliary valves relief.
The only time you need to send fluid through the fill port in the TC block is if you use a power beyond kit on your Cub (which isn't needed). If you had a power beyond kit on your valve (again, not needed) it would be plumbed something like this.

[Nautiluscont]

Thanks guys!

Ricky, my setup is largely based off your setup. What was the reason you plumbed the (extra) line from the power beyond port to return port on the bypass and then the t port to the tank? Was it simply because your valve had both ports?

[ricky racer]

I was under the understanding that I needed the power beyond added to the valve. That proved to not be the case. It's been a lot of years since I plumbed up my valve and don't honestly remember why it was plumbed that way. All I know is it works great.

[Matt Kirsch]

Rick Prentice just did a nice write-up on how a power beyond valve works.

IMHO at the low pressure and volume of a Cub hydraulic system, power beyond is not absolutely necessary. Farmers have been stacking regular old four-way spool valves on old tractors for 70+ years, IN to OUT to IN to OUT and back to the tractor. True, power beyond is the "right" way to do it, but the valves are plenty strong to deal with ~1500PSI.

[SamsFarm]

Rick Prentice just did a nice write-up on how a power beyond valve works.

IMHO at the low pressure and volume of a Cub hydraulic system, power beyond is not absolutely necessary. Farmers have been stacking regular old four-way spool valves on old tractors for 70+ years, IN to OUT to IN to OUT and back to the tractor. True, power beyond is the "right" way to do it, but the valves are plenty strong to deal with ~1500PSI.

Rick's write up.

viewtopic.php?f=1&t=109793&p=871956&sid=e17a7e374b5f63381bedaf163bc51bde#p871956

While I have not played with aux hydraulics on the cub, I have on other things.

If the touch control unit has the relief valve (I am betting it does), and your new valve does not have a relief valve built in, then the potential to dead end your hydraulic pump exists!

When that happens pressure will spike past the point the cub's system was designed for and you could damage your pump, blow out seals, or maybe rupture the metal lines if they have a weak spot from rust or wear from rubbing on something!

[Jim Becker]

. . . If the touch control unit has the relief valve (I am betting it does), and your new valve does not have a relief valve built in, then the potential to dead end your hydraulic pump exists! . . .

You are correct, on both counts. Furthermore, if you do have a relief valve in the new valve and don't plumb it correctly, you still may in effect dead end the system. The return through the relief valve needs to go straight back to the reservoir, not the bypass block.

[SamsFarm]

Furthermore, if you do have a relief valve in the new valve and don't plumb it correctly, you still may in effect dead end the system. The return through the relief valve needs to go straight back to the reservoir, not the bypass block.

I think that depends on what valve you have and whether the relief valve dumps into the hydraulic return port, or has its own dedicated return port!

My 3 point log splitter and Shaver post pounder are 2 hose systems and have their relief valve dump into the return line.

See the Prince valve below!

Edit; The Prince valve pictured below is NOT acceptable to as a grader blade angle valve!

My 4520 Deere has a power beyond system that I use for them. Deere warns that damage could result from running the tractor with the power beyond not connected to itself or another valve that has the relief valve built in!

My Deere power beyond system in nothing more than if you had the bypass block installed on your Cub with a female quick coupler attached to the pressure side and a hose with a male quick coupler attached to the return side.

Plug them together to operate the touch control, but disconnect them (with the tractor not running) and plug the pressure into your log splitter, or something similar that would be used while the touch control is inoperable, plug your return line into the touch control fill port!

Happy tractoring!

[Jim Becker]

That Prince valve does not appear to be a power beyond valve. Any flow from the relief valve is evidently dumped to the "out" connection. As I said previously, that "out" needs to run directly to the reservoir. If it is plumbed back into the bypass block, there is a risk of over-pressuring the system.

[SamsFarm]

I guess the biggest question, what does the International technical manual say?

[Jim Becker]

As far as i know, IH's only use of the bypass block on a Cub was for the model 1000 Loader. It uses a double valve assembly, one set up as two-way, the other set up as one-way. There is a pressure relief valve at the inlet end. Outflow from it and the return from both valves is collected into a single outlet/tube that returns flow to the tank built into the loader frame. A power beyond outlet is on the opposite end of the assembly from the relief valve. That outlet connects back to the bypass block to feed the Touch-Control valve. Another hose runs from the bottom of the loader frame tank to the filler of the Touch-Control.

[SamsFarm]

Here is the schematic from the Prince hydraulics.

It is showing in a round about way what Jim is describing in the 1000 loader hook-up!

http://www.princehyd.com/portals/0/tech ... erPbDA.pdf

[Jim Becker]

Here is the schematic from the Prince hydraulics.

It is showing in a round about way what Jim is describing in the 1000 loader hook-up!

http://www.princehyd.com/portals/0/tech ... erPbDA.pdf

The third drawing is the dangerous situation I've been trying to explain. The valves in the drawings appear to be drawn to include a pressure relief. Assume they are both set for 1,500 psi. If the downstream circuit hits a hard stop, the high pressure lines will all be at 1,500 psi. Now throw in the possibility that both valves are actuated and hit a hard stop at about the same time. You now have 1,500 psi on the line feeding the downstream valve. Since it is the same line as the return from the upstream valve, the upstream outlet pressure is 1,500 psi. The upstream pressure relief won't open until it senses ANOTHER 1,500 psi. So everything from that relief valve back to and including the pump has 3,000 psi. That is when things start exploding.