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Gear flow divider pressure

One product I’m working on has a gear type flow divider. This is a unit with mechanically linked four gear motors:

Today was asked the question: what happen if some of the lines be broken or leaking:

Somebody who is not familiar good enough with hydraulics can be confusing to know that the pressure at the actuator can be increased in this case. Moreover, the in this case the flow divider will work as a pressure multiplication device.

Why?

The answer we can get if research this device from the point of power transfer.

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IFPS Upgrades HS Certification

Hydraulic Specialist certification manual

Hydraulic Specialist certification manual

The International Fluid Power Society (IFPS) has recently upgraded its Hydraulic Specialist (CFPHS) Certification Study Manual.

Testing for the CFPHS certification starts today, April 1, 2017.

“To keep pace with changing fluid power and motion control technologies, IFPS is committed to reviewing our certification study manuals and tests every five years by a panel of subject matter experts. All material is reviewed for relevance and current technical best practices and standards,” said Donna Pollander, ACA, IFPS executive director. “What the IFPS provides in our newly updated HS study manual and certification test is a highly developed, vendor-neutral, benchmarking tool to evaluate an individual’s fluid power competence, knowledge, and skill set.”

Source: http://fluidpowerjournal.com/2017/03/ifps-upgrades-hydraulic-specialist-certification/

The manual is good, and I like it. But, by my opinion, some stuff has to be changed in this manual:

  1. The font is terrible. I think “Verdana” is not a best choice for study manuals. Standard “serif”-type font like “Times New Roman” is much better for fast reading when there are a lot of sentences in the paragraph.
  2. Text lines are too close to each other. Line spacing in paragraph has to be bigger to easy reading. And I think, it is good idea to use two columns at the page.
  3. Some pictures are raster and in bad resolution. By my opinion, all images have to be in vector format and all photos have to be at least 400 dpi resolution.
  4. Symbols at the schematics are not in accordance with ISO 1219-1. This is a manual for hydraulic certification – you must to follow the standard! (lines type and weight, symbol size, etc.). Schematics made in strange

This is very sad! We pay money for membership, for exams, but IFPS can’t (or doesn’t want) find good specialists to prepare study manual in an acceptable quality!

Proportional valve control calculation. Part 2.

Part 2. Proportional control in the regeneration mode.

Regen mode - proportional control

Fig.1. Regeneration mode schematic

See also:
Part 1. Proportional control of double acting hydraulic cylinder.
Online calculator for cylinder proportional control.

The goal of the calculation is definition of a cylinder velocity at the current operating voltage at the valve’s solenoid.
For calculations we need to know: cylinder and valve parameters (take them from manufacturer catalog), values of forces at cylinder rod (load) and pressure drop at return line (can be assumed as zero if unknown).

Summary:
2.1. Regeneration mode schematic
2.2. Regeneration Mode: Cylinder extension calculation
2.2.1. Balance of forces at the cylinder
2.2.2. Spool lands ratio and pressure drops at the spool lands
2.2.3. Hydraulic cylinder extension. System pressure calculation
2.2.4. Flow through spool lands: max. and at current voltage
2.3. Hydraulic cylinder retraction calculation
2.4. Final words….

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