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Charging Pump On A Sunstrand.


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#1 Donnie OFFLINE  

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Posted March 04, 2013 - 10:40 AM

I am new to hydraulic priciples, and have read some great tutorials that have been linked here. I noticed that on a Sunstrand inline hydrostatic  transmission, there is a need for a charging pump due to cavitation. Is this because that the case serves as the resevoir ? Is air entering the line because the case cannot be filled completely ? It seems if I am correct the same components running seperately , with a seperate reservoir have no need for a charge pump.

 

 

I should never started studying hydraulics !  Its like a drug !  I find myself mulling over questions all the time now, like a child, why? why ? why ?

 

Thanks for taking the time to read guys ! :wave:

 

sorry for the edit, I was wondering if it could be due to the res not being higher than the pump, no flow to the pump.


Edited by Donnie, March 04, 2013 - 10:42 AM.

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#2 JRJ OFFLINE  

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Posted March 04, 2013 - 11:26 AM

Welcome to GTTalk, if I was you sitution I would find myself the manual that deals with the hydraulics of your make and model of tradtor.

 

Dick



#3 Guest_rat88_*

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Posted March 04, 2013 - 11:37 AM

The charge pump provides positive pressure for the suction side of the main pump, it kinda works like a 2 stage air compressor.


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#4 JDBrian OFFLINE  

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Posted March 04, 2013 - 11:40 AM

This link may help. http://www.machinery...mission-leakage


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#5 WNYTractorTinkerer OFFLINE  

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Posted March 04, 2013 - 12:14 PM

Welcome aboard Donnie!!

 

A Hydro-static tranny isn't a true hydraulic system as the pump has variable output.  A hydraulic pump pumps oil at a speed @ engine RPM and that's it..  The hydro's pump has a movable mechanism or plate that changes the amount of oil pumped and regulates oil flow / tranny speed in that way..  Once you look @ one's inner parts and design you will see what I'm saying..  

 

Enjoy GTtalk!!  



#6 olcowhand ONLINE  

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Posted March 04, 2013 - 12:17 PM

The charge pump provides positive pressure for the suction side of the main pump, it kinda works like a 2 stage air compressor.

 

And the charge pump also serves for the lift circuit pressure, plus keeps the oil flowing in & around the hydro while it's in neutral position.



#7 New.Canadian.DB.Owner ONLINE  

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Posted March 04, 2013 - 05:47 PM

... Is this because that the case serves as the resevoir ? ...

 

I'd have to say no.  The T66 Vickers that was used by Allis & Simplicity have both a charging pump & a reservoir.  The Vickers was replaced by the Sunstrand in later models.


Edited by New.Canadian.DB.Owner, March 04, 2013 - 05:48 PM.


#8 coldone OFFLINE  

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Posted March 04, 2013 - 10:10 PM

Another use of the charge pump as it relates to the hydrostatic circuit is as a make up pump. With a hydro static ciruit there are internal losses of fluid due to clearences of the moving parts. The charge pump adds to the ciruit to make up these internal losses. A great place to start with hydros as they relate to GTs is the sundtrand 15 series manual. The 15 and its variants were used in a dozen or more different GTs. Check out the manual section here at GTT to get a copy.


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#9 ol' stonebreaker OFFLINE  

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Posted March 04, 2013 - 10:43 PM

Another use of the charge pump as it relates to the hydrostatic circuit is as a make up pump. With a hydro static ciruit there are internal losses of fluid due to clearences of the moving parts. The charge pump adds to the ciruit to make up these internal losses. A great place to start with hydros as they relate to GTs is the sundtrand 15 series manual. The 15 and its variants were used in a dozen or more different GTs. Check out the manual section here at GTT to get a copy.

   That is the primary purpose of the charge pump. The hydro trans circuit must have a positve pressure in order to function.

                                                                 Mike



#10 Guest_rat88_*

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Posted March 05, 2013 - 06:34 AM

Welcome aboard Donnie!!

 

A Hydro-static tranny isn't a true hydraulic system as the pump has variable output.  A hydraulic pump pumps oil at a speed @ engine RPM and that's it..  The hydro's pump has a movable mechanism or plate that changes the amount of oil pumped and regulates oil flow / tranny speed in that way..  Once you look @ one's inner parts and design you will see what I'm saying..  

 

Enjoy GTtalk!!  

 

 

There are variable displacment hydraulic pumps that increase or decrease flow by using pressure to adjust the swash plate. They work kinda like a pnuematic back pressure regulator.

A hydrostat is just the manual version of this.






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