Design-your-own 3rd Function

[J_J]

How does one know about hyd, you say, manuals, books, DVD's, hyd courses, YouTube videos and you can learn a lot on forums like TBN.

Also, just your questions here and someone should be able to answer.

Your manual should tell you about your hyd system.

But anyway, you and your dad's tractors are open center hyd systems, where the pump is pumping all the time the engine is running.

All valves are in series.

The pumped fluid passes through all valves to tank when the levers are in neutral.

When you move the levers, you re-route the fluid to the hyd component be it a cyl or hyd motor.

Some of the hyd valves are for convenience. You select the type valve/spool to accomplish the task.

If you want float, select a spool that has float.

If you want to control a hyd motor, you select a motor spool.

If you want regen, you select a valve with a regen spool.

A lever type valve will let you feather the valve for slow and precise work.

A solenoid valve works fine in some situations, and is usually full flow.

The GPM's pumped is dictated by the engine rpm.

You can probably get everything from here.

Surplus Center

http://www.baileynet.com/categories

 

[MinnesotaEric]

How does one know such things? What does that even mean?

Closed center is like the water system in your house: always under pressure and fluid does not move till the valve is opened. Open center is like a spray pump where the water goes round and round the system till it is needed, then diverted off in another direction by a valve.

 

[kennyd]

Closed center is like the water system in your house: always under pressure and fluid does not move till the valve is opened. Open center is like a spray pump where the water goes round and round the system till it is needed, then diverted off in another direction by a valve.

:thumbsup: Great explanation Eric!

 

[aeblank]

Closed center is like the water system in your house: always under pressure and fluid does not move till the valve is opened. Open center is like a spray pump where the water goes round and round the system till it is needed, then diverted off in another direction by a valve.

Are any variable pumps, or all fixed displacement?

The above seems like constant pressure for the first, and constant flow for the second...... Or they're fixed displacement. =)

 

[J_J]

Excerpts:

Open center circuits use pumps which supply a continuous flow. The flow is returned to tank through the control valve's open center; that is, when the control valve is centered, it provides an open return path to tank and the fluid is not pumped to a high pressure

Closed center valve type, where the pump flow is blocked when valve spool is in neutral. When LS-valves are used combined with fixed displacement pumps, a special valve is incorporated in the inlet section of the the valve block to unload the pump, making the system work as an "open center" but the valves are still closed centers in neutral.

Variable speed pumps are used in hydrostatic transmissions.

NO flow or pressure through the pump in neutral except the charge flow, which is about 10% of total flow.

 

[Rocky Hoffler]

I put one on a 3700 Kubota had a 3 stack valve took two of the sections off and used only one had a hard time finding a control so I uased a pendant from a winch there is a very good info video on you tube just search third function valve usaed bosch relays to control the solenolds as my pendant was not real heavy duty I believe the valve was a Do5 its what I had but a smaller Do3 is what must folks use had a little problem with mounting it out of the way so as not to interfere with brake pedals my tractor was hydrostactic so who uses brakes any way

 

[J_J]

The L3700 attachment pump had a flow of 6.8 gpm.

D05 was over kill, besides more expensive.

 

[MinnesotaEric]

Excerpts:

Open center circuits use pumps which supply a continuous flow. The flow is returned to tank through the control valve's open center; that is, when the control valve is centered, it provides an open return path to tank and the fluid is not pumped to a high pressure

Closed center valve type, where the pump flow is blocked when valve spool is in neutral. When LS-valves are used combined with fixed displacement pumps, a special valve is incorporated in the inlet section of the the valve block to unload the pump, making the system work as an "open center" but the valves are still closed centers in neutral.

Variable speed pumps are used in hydrostatic transmissions.

NO flow or pressure through the pump except the charge flow, which is about 10% of total flow.

That is an excellent description. Way better than the slurpy machine at the 7-11 I had been thinking of using.

 

[Rocky Hoffler]

the d05 valve was more expensive buy I guess I didn't mention it was free cheap is good but free is better

 

[oldnslo]

Some things to consider when using electric operated valves like D03 or D05:
1) Will the "tank" port be pressurized? If yes confirm that the valve you selecting is rated for working pressure in the tank port.
2) Solenoid operated valves provide no metering for slow controlled load movement. They are on or off like a light switch. if you want the ability infinite speed control these are NOT the valves of choice.
3) Coil termination: Hirschman connectors are very common but corrode over time in wet environments. Pre-molded cables reduce this problem. Deustch connectors are sealed much better but usually require special tools to assemble the wire ends or purchasing pre-made cables. Deustch are also less common on industrial style D0* style valves.
4) Spool type Vs pressure drop: Typically the tandem center spool (P to T, A & B blocked) has the highest pressure drop and lowest flow rating of any spool in a given valve size. In open center series circuits the fluid is always flowing so pressure drop = energy loss and heat generation.