Gates Belts & Applications - Tips and guidelines written by Gates Industrial Engineers

Learn the Terminology

Monday, November 7, 2016

posted by Brent at 11:06 AM 0 comments


Cut-Off Length:  The length of that part of the coupling not directly in contact with or applied to the hose. Subtract the sum of the cut-off length of the two couplings from the total length of the assembly, and you will have the approximate hose-cut length to be replaced.
Dash Size:   A shorthand method of denoting the size of a particular end fitting or the inside diameter of a hose.  Measured in 1/16 of an inch (i.e., -4 = 4/16” or ¼”).

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Hose Cleanliness – Methods of measurement Part 2

There are three principal methods to measure the contamination level in a component, circuit, or system:

1) Gravimetric Measurement (ISO 4405)

2) Particle Size Distribution Analysis (ISO 4406 or NAS 1638)

3) Maximum Particle Size Analysis (ISO 4407).

This post will discuss the second method (above).

Particle Size Distribution Analysis (ISO 4406 or NAS1638) 

Particle Size Distribution Analysis is a reporting method to gauge both the size and number of contaminant particles in a calculated quantity of hydraulic fluid.  A fluid sample is either taken directly out of a hydraulic system or a known quantity of fluid is used to dislodge contaminants out of a hydraulic component. This fluid is run through a particle counting instrument to size and count contaminant particles.

These particle ‘counts’ can then be normalized by comparing the total component volume and to a corresponding ISO 4406 ‘code’ level of particle contamination. Levels of five and 15 microns of contamination are reported on a logarithmic scale corresponding to and ISO 4406 ‘code’ for the number of particles greater than or equal to these respective sizes per milliliter of fluid.
 


 

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Hose Cleanliness – affects Valves, Pumps, System cooling

Monday, October 24, 2016

posted by Brent at 1:03 PM 0 comments


Valves: Microscopic contamination (similar to erosion) can mill away tolerances which are used for sealing purposes. On spring centering valves, the debris may get caught between the valve and the wall surface. The contamination will cause the slowing down of the motion of the valve or causing sluggish or adverse mechanical actuation.

Abrasive particles enter the clearances between moving parts they score and hone the surfaces to greater tolerances. As these tolerances broaden, system performance is compromised by pressure losses incurred due to fluid leakage from high to lower pressures.

The worst occurrence is when particles that are greater than or equal in size to the orifice openings become wedged between the two surfaces. The contamination may cause wear to occur or it may cause the system components to seize.

Pumps & drives: Microscopic contamination can mill away material, creating leak points. These leak points rob the hydraulic system of pressure and cause poor responsiveness.

System cooling: Working fluid may not flow through to remove contaminants generated from metal to metal contact when passages become blocked. Lower flow rates mean greater heat buildup in systems and thermal breakdown of the working fluid.

 

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Hose Cleanliness - Origin of Contamination


Origins of contamination may be from system components, the hydraulic working fluid, the outside environment, or be generated by the system itself. These contaminants, some large and some microscopic, can have a profound impact on the performance and longevity of the hydraulic system.

There are three principal means through which contamination can
occur in a typical hydraulic system. 

Contamination can be:

1.    Generated during system operation

2.    Built into the system during assembly

3.     Ingested by the system during operation

 The working fluid in hydraulic systems should be as homogeneous as possible and free of all visible and microscopic debris for optimum performance. The complete absence of contamination in hydraulic systems is unrealistic, but an acceptable and defined level of contamination is generally considered hydraulic system cleanliness. The best approach to cleanliness is to prevent contamination in the first place. Use clean hose and couplings and keep them clean (i.e. cap ends). Clean hose bore after cutting to length as cutting hose to length is a major contributor to contamination.

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Blast from the Past

Monday, October 17, 2016

posted by Brent at 12:18 PM 0 comments

This old technical note surfaced recently from a Product Application department discussion.  While dated, it does point out that a good technique for evaluating vibration is to determine if there is vibration present beyond the belt drive system.




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Learn the Terminology - Fluid Power

Tuesday, October 4, 2016

posted by Brent at 1:06 PM 0 comments


Compressibility:  The change in volume of a unit volume of a fluid when subjected to a unit change of pressure.

Contaminant:  Any material or substance that is unwanted or adversely affects the fluid power system or components or both.

Corrosion: The chemical change in the mechanical elements caused by the interaction of fluid or contaminants or both. More specifically related to chemical changes in  metals. The products of change may be introduced into the system as generated particulate contamination.

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Fluid Power: Learn the Terminology - Cavitation

Wednesday, September 7, 2016

posted by Brent at 7:36 AM 0 comments


Cavitation: A localized gaseous condition within a liquid stream causing the rapid implosion of a gaseous bubble.

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