EHD Film Thickness


Are you interested in determining if the open gear lubricant you are using is the best product for your application? Internationally recognized methods exist to calculate film thickness. The calculation is called an Elastrohydrodynamic (EHD) Film Thickness Analysis. Both the American Gear Manufacturers Association (AGMA) and the International Standards Organization (ISO) recognize the importance of using the correct open gear lubricant to ensure gearing performs as it was designed.

Ring (girth) gears are typically designed for at least a 25 year service life. Why do some gears and particularly pinions only last a few years? What is the most common cause of ring (girth) gearing failures? (A) Wear. To increase service life, wear must be reduced or eliminated. Many lubricants contain friction modifiers to reduce wear. Unfortunately, these friction modifiers are only effective under conditions of boundary lubrication (startup or with very low values of lambda). To reduce wear as much as possible, the gearing should operate under full EHD where there is sufficient lubricant film thickness to prevent metal-to-metal contact of the tooth surfaces.

Using a new proprietary computer program, Petron Corporation can perform the needed Elastrohydrodynamic (EHD) Film Thickness Analysis and quickly calculate Lambda. The program was written to be user friendly requiring a minimum of input information but still utilizing the same complex calculation as described in AGMA and ISO standards. To employ a consultant to perform this analysis would typically cost hundreds, if not thousands of dollars. Because Petron’s new computer program is user friendly with simplified input, Petron can perform this analysis quickly and at no charge.

If you would like to have an EHD Film Thickness Analysis run for a specific gear set, please submit the completed EHD Required Information Form and we will run the analysis and email back to you.

Required Information

In order to run this test, the following data is required. Once you have gathered this data, you can either 1) submit your data on form below , or 2) download the EHD Film Thickness form and fax it to our company.

Submit EHD Analysis Request

    Personal Information

    First Name*

    Last Name*





    EHD Information

    Number of Pinion Teeth*

    Number of Gear Teeth*

    Pinion Speed (RPM)*

    Gear Face Width*


    Tooth Pitch*

    Pinion Tooth Temperature*

    Gear Type*

    Normal Tooth Pressure Angle*

    Tooth Condition*

    Current Lubricant Used*

    Additional Lubricant*