May 082013
 

This page is a continuation of How to Design a Flat Belt Drive [Step-by-step Tutorial] – Page 3.

Step 7 – Finding Load Rating at V m/s:

For “HI – SPEED” 878 g duck belting, load rating at 10 m/s is 0.023 kW per mm per ply.

For “FORT” 949 g duck belting, load rating at 10m/s is 0.0289 kW per mm per ply.

Load rating at V m/s = Load rating at 10 m/s × (V/10) kW per mm per ply

Note: If you are using PSG design data book, refer page no. 7.54 (May 2012 reprint) for finding the load rating.

Step 8 – Finding Belt Width (b):

Width of belt (b) can be found using the following equation:

b~=~{{Design~Power}/{No.~of~plies~*~Load~Rating}}~mm

In the above equation, load rating implies load rating at V m/s that you have found in the previous step.

After finding the belt width, you must change it to the nearest standard value (greater than the one determined) and fix it as the permanent value. Refer the following table to choose a standard belt width according to the number of plies and the type of belt used.

Table (v) – Standard Flat Belt Widths in mm

 3 Plies  4 Plies  5 Plies  6 Plies 8 Plies
 25◊ 25• 76◊ 100• 200¤
32• 32• 90• 112◊ 250¤
40◊ 40◊ 100◊ 125◊ 305¤
44• 44◊ 112◊ 152◊ 355¤
50◊ 50◊ 125◊ 180◊ 400¤
63◊ 63◊ 152◊ 200◊
76◊  76◊ 180¤ 250¤
90•  90◊ 200•
100• 100◊ 224•
112◊ 250¤
125◊
140•
152◊
200•

In the above table,

◊ → Sizes available in both “HI-SPEED” and “FORT” duck belting

• → Sizes available only in “HI-SPEED” duck belting

¤ → Sizes available only in “FORT” duck belting

Note: If you are using PSG design data book, refer page no. 7.52 (May 2012 reprint) for the above table.

Step 9 – Determining Pulley width:

Pulley width can be obtained using the following equation:

Pulley width = Belt width (chosen standard) + Additional width

Additional width has to be chosen according to the belt width. The following table helps you do that.

Table (vi) – Determination of Additional Width from Belt Width

 Belt Width  Additional width
Upto and including 125 mm  13 mm
Above 125 mm upto and including 250 mm  25 mm
Above 250 mm upto and including 375 mm 38 mm
Above 375 mm upto and including 500 mm 50 mm

Note: If you are using PSG design data book, refer page no. 7.54 (May 2012 reprint) for this table.

Once the pulley width is found, you must change it to the nearest standard value (greater than the one determined) and fix it as the permanent value.

A list of standard pulley widths (in mm) is given below:

20, 25, 32, 40, 50, 63, 71, 80, 90, 100, 112, 125, 140, 160, 180, 200, 224, 250, 280, 315, 355, 400, 450, 500, 560, 630

Note: If you are using PSG design data book, refer page no. 7.55 (May 2012 reprint) for finding the standard pulley width.

Step 10 – Determining the length of flat belt (L):

This is the last step. Length of belt varies according to the type of flat belt drive.

For open flat belt drive, length of belt is given by:

L~=~2C~+~{pi/2}(D~+~d)~+~{{(D~-~d)^2}/4C}

For crossed flat belt drive, length of belt is given by:

L~=~2C~+~{pi/2}(D~+~d)~+~{{(D~+~d)^2}/4C}

For quarter turn flat belt drive, length of belt is given by:

L~={pi/2}(D~+~d)~+~sqrt{C^2~+~D^2}~+~sqrt{C^2~+~d^2}

where,

D → Diameter of the larger pulley

d → Diameter of the smaller pulley

C → Centre distance between the two pulleys

Note: If you are using PSG design data book, refer page no. 7.53 (May 2012 reprint) for these length formulae.

That’s it. You have successfully designed a flat belt drive using manufacturer’s data :)

If you have any ideas or feedbacks, feel free to comment on this article :)

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I am a mechanical engineer with a passion for technical stuff. I am the founder and former editor-in-chief of Mechteacher.com.

  • http://www.facebook.com/vrdh22 Varadha Yamunan

    Good one :) Helped me pretty well.. Thank you

    • http://mechteacher.com/ Surjeet S

      You are welcome… Get fresh content from mechteacher.com by liking us on facebook and subscribing to our e-mail newsletter :)
      Our facebook page: http://facebook.com/mechteacher

  • pradeep patil

    While designing belt drive set the centre height of both pulley shall be same?
    what is effect on power transmission if their is height difference?

    • http://mechteacher.com/ Surjeet S

      The heights of the pulley centers from ground depend on the height difference between the driving and driven shafts. They may or may not be the same. If there is a height difference, the centre to centre distance (between the pulleys) increases. This will have a direct impact on the arc of contact and the design power we calculate.

      • Sarungbam Romen Singh

        Hello Surjeet,
        In the Book “Design of Machine elements” by VB Bhandhari, the arc of contact factor, Fd is multiplied with the rated power while as per the formula you’ve referred here, the said factor divides the rated power.
        [Corrected Power= {(load correction factor x rated power) x arc of contact factor}]
        Please clear me this confusion I m having with.
        I am just an Electrical Engg. Student working on the flat belt drives.
        Thanking you in anticipation.

  • Ron Verduguez

    can you give the references of the equations that you used on this design? thank you…

    • http://mechteacher.com/ Surjeet S

      These equations can be found in any standard design databook. In India, we normally follow PSG Design Databook

      • Ron Verduguez

        thank you…

  • Dineshraj Srinivasan

    can you give design calculation for the v-belt drives ?

  • Hem Shailabh

    Hi! Can you tell me why the product of coefficient of friction and angle of wrap is minimized when designing open belt drives for certain maximum stress? Please reply asap. @Surjeet_S:disqus I am yet to start studying DME, i asked this from my knowledge of Kinematics-OM. Thanks

  • http://medtechnicstz.com Eng Medson Naftal

    Thanks i understand well