Tapping off the hydraulic pump?

[Chadtoolio]

I have a Ariens GT17 tractor that I am restoring and was wanting to use the hydraulics for other implements. Is it possible to put a T into the pressure side of the hydraulic hose going to the current control levers and add another set of control levers? Or, I could T off of the current control lever output hoses(the one that goes to the ram), that way I could utilize the control levers that are already on the tractor. I would then have to use some type of valves that changed the fluid delivery from the stock location to the new port/implement. The next question is the fluid capacity of the hydro pump and stock ram size. If I used an additional ram, say for a loader or a log splitter, the piston in the ram would be longer and require more fluid delivery and would require more fluid. Should I add a hose to the fill plug of the pump and connect it to an additional reservoir? Any other ideas? Will a ram with 2 hoses connected to it have a power up and down? I have heard of some people saying that a 3ph does not have a power down. Just wondering, because it didn't make sense to me having a tiller hooked up and couldn't push it into the soil!

Thanks,

Chad

 

[MadReferee]

re: Is it possible to put a T into the pressure side of the hydraulic hose going to the current control levers and add another set of control levers?

Technically speaking, no, assuming your system is open center.

Instead of teeing, run the pressure hose to the inlet of your new valve block which must have a power beyond port. Then take the power beyond port from your new block and run it to the inlet side of the existing block (ie. they will be in series). The outlet side of your new block should return to the hydraulic reservoir.

Generally speaking, you should never tee off of a pressure line. Teeing off the return to tank/resevoir line is ok since this is a not normally pressurized line.

 

[Chadtoolio]

Ref,

When you say "open center", you mean that without the current control lever engaged there is no pressure? Like no pressure build up, just return... That would make sense. So you are saying that by using an addition valve, it would build up the pressure to use and return through the other(stock control valve). Bing, Bing Bing,-lightbulb goes on! Where can I find such valves for such application?

Thanks,

Chad

 

[MadReferee]

Open center systems have a hydraulic pump that is always pumping. Fluid must continuously pass thru the valve block when the lever(s) are in the center or neutral position. This is the typical system in compact tractors.

Closed center systems the hydraulic pump can rest when the fluid is not required to operate a function. This means that a control valve is closed in the center or neutral position, stopping the flow of the fluid from the pump.

In your case you have to determine how the pumps works, whether it is continuous or on demand.

 

[MadReferee]

When you figure out what hydraulic pump you have, you can then go and get the appropriate valve block. Some good places are Surplus Center, PrinceDirect, and BaileyNet. Surplus Center will be the cheapest.

 

[uhmgawa]

</font><font color="blue" class="small">( Open center systems have a hydraulic pump that is always pumping. Fluid must continuously pass thru the valve block when the lever(s) are in the center or neutral position. This is the typical system in compact tractors. )</font>

I'd be surprised if it wasn't open center. This seems to be most common as
the hydraulic pumps are much lower cost. Closed center does have some
advantages though. Such as sizing a valve solely for the intended flow of
the work ports. With open center you also need to take into consideration
the series flow restriction of the valve you are adding. This can mean
using a larger GPM valve than you actually need to minimize pressure
drop seen by valves down stream.

 

[stephan]

Thanks for that explanation on open vs closed. That was one of those questions I always wanted to know the answer to but was afraid to ask?

 

[SPIKER]

to get a bit more techincal the OPEN center systems use pumps that are pretty much just like a hydraulic motor. fixed rotor/piston type designs that opperate similar to a car engine the pistons move the same distance and pump the same amount of fluid per revolution (not including bypass leaks in the piston walls) each time. this means if the pump ios rotating the fluid has to go someplace or else it will over pressurize and break something. the OPEN center valves let the fluid flow through them and back to the pump resiviour and when you want to move the valve RE-DIRRECTS the flow to a actuator of some type. there the force resisting the actuator's movement is what causes pressure to build. like I said these pumps will build pressure untill one of two things happen , the actuator moves or something breaks. (lines hoses, actuator mounts ect.)

a closed system requires a varriable volume pump which actually pumps fluid volume only when it has some place to go, other wise the pumps displacement changes and the piston doesn't push out the fluid as normal. there are many different types of pumps usually a cam type rub/wear plate forces the piston to either move up or stay flat and the higher the change in angle the more the piston moves. these types of pumps can over heat if left at pressure for long periods of time so dont leave them run unattended with out the need for flow. usually a spring system upstream of the pump lets fluid pressure back behind the walking cam plate which as the pressure increases the cam angle decreases untill the cam is flat and 0 flow is going out, this requires a OUTPUT pressure and is usually adjustable on the pump or the return line but is normally NOT END USER ADJUSTABLE! don't try to adjust them that means.

ok hope that helps.

BTW nice Hydraulic site posted above.

Mark M /forums/images/graemlins/smile.gif