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Tag Archive: pump

Parker’s Gold Cup pumps: External filtration

Have you ever dealt with Parker’s Gold Cup pumps? If yes, you probably noted in the product datasheet, this pump does not require to have filtration of internal charge (boost/replenishing) pumps flow. There is just a short recommendation “the auxiliary pump fluid be filtered to aid in maintaining acceptable cleanliness levels”:

The reason for that is because Parker thinks all close loop systems need to be designed to ensure “the oil tank is protected through filtration from any ingress contamination”. Later I shall show you Parker’s document where this statement is coming from (AS-0018). Actually, question to you: do you agree with this statement?

I do not. I use charge (boost/replenishing) flow filtration for every single close loop pump at every single project via an external filter connection. Moreover, both proportional and servo control systems require even more fine cleanliness level of the element for filtration, therefore for such systems I use two separate filters: for charge flow (usually 10 mkm element) and for servo control flow (usually 2 mkm element).

But there are a couple of problems with the Gold Cup pump external filtration. Although these pumps have ports for external filtration and even a short guide in the datasheet on how to make filtration (screenshot above) due to design of internal galleries is different for all three Gold Cup pump frame sizes, and, in addition, is different for specific side a control system is mounted on, you will not be able to provide a correct filtration and even can destroy the pump if connect external filter in the wrong way. And this problem is not explained and not resolved in the product catalogue.

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Parker Gold Cup IE (Intelligence Enabled)

Parker Gold Cup IE

Parker Gold Cup IE

Parker introduced Gold Cup – IE (Intelligence Enabled) pump.

In general, this is just the new option “E” at the secondary control option for the “9A” electro-hydraulic stroker as the primary control. This option combines the robust design of Gold Cup pump technology with the intelligence of operational sensors and analytics.

Example model number:

P11P3R1C9AEB00

Read more at the PDF document Introducing Gold Cup – IE (Intelligence Enabled).

In my opinion, this option is not for every application, because most sensors are not required for regular tasks. But probably there are exist some sensitive applications where all components should be monitored in real-time (where the high cost of downtime) for detecting failure before it occurs.

Rexroth A4VG clones

Just in case if you need replacement for Rexroth A4VG, it seems to me these guys are brothers:

Rexroth A4VG Parker C-series Dana Brevini S6CV
Rexroth A4VG Parker C-series Dana Brevini S6CV
Available Displacements:
28cc, 40cc, 56cc, 71cc, 90cc, 125cc 55cc, 81cc, 136cc 75cc, 128cc
Nominal pressure:
400 bar (5800 psi) 420 bar (6090 psi) 400 bar (5800 psi)
Maximum Permissible Fluid Cleanliness:
20/18/15 20/18/15 20/18/15
Operating temperature:
−25..+110 °C -25..90 °C -25..90 °C
Viscosity range at operating temperature:
16..36 cSt 15..40 cSt 15..40 cSt
Available control systems:
HD” Proportional control, hydraulic C” Hydraulic proportional control with internal feedback HIR” Hydraulic proportional with feed-back
EP” Proportional control, electric F” Electric proportional with internal feedback HER” Electric proportional with feed-back
ET” Electric control, direct operated, two pressure reducing valves G” Electric proportional without internal feedback HEN” Electric proportional without feed-back
EZ” Two-point control, electric E” Electric non proportional HE2” Electric on-off
DG” Hydraulic control, direct operated D” Hydraulic proportional control without internal feedback HIN” Hydraulic proportional without feed-back
– – – A” Manual lever HLR” Manual lever with feed-back

Semi-closed hydraulic circuits

Have you ever heard about the semi-closed hydraulic circuit?

The idea is to use open loop pumps in closed loop circuit. In the latest eighties, Mannesmann Rexroth (yes, that time Mannesmann yet!) even offered pumps A4VSH, especially designed for semi-closed circuits.

Bosch Rexroth A4VSH pump

Bosch Rexroth A4VSH pump, from catalog RE92110/01.89

The main difference between closed loop pumps and semi-closed loop pumps was in addition block mounted to the ports A and B with check valves which let to supply suction flow from the tank, while mainstream comes from the motor to pump’s suction port:

Since that time Rexroth still builds A4VSH, but there are a limited number of sizes and options available and its no longer a mainstream published option.

But to make a semi-closed loop you do not need some special pump, it’s really easy to turn most standard open loop pump into a semi-closed loop circuit. Of course, you have to have some knowledge about the application and actuators before trying to apply it. If the pump does not have an integrated boost pump and check valves these are commonly added via an external gear pump and external check valves.

Here is the simplest example of the semi-closed circuit schematic where a regular open loop pump with LS control is involved to run two motors with independent proportional control of their speeds:
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