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Philippine Agricultural Engineering Standard PAES 301:2000

• This standard provides specifications and technical data for V-belts and pulleys used in drives for agricultural machinery.

Foreword

• The Agricultural Machinery Testing and Evaluation Center (AMTEC) initiated the formulation of the national standard.
• The project, "Enhancing the Implementation of AFMA Through Improved Agricultural Engineering Standards," was funded by the Bureau of Agricultural Research (BAR) of the Department of Agriculture (DA).
• The Technical Committee for Study 2 reviewed the standard.
• The Technical Committee was concerned with the Development of Standards for Engineering Materials.
• The Philippine Society of Agricultural Engineers (PSAE) reviewed these standards and subjected to a public hearing by the National Agriculture and Fisheries Council (NAFC).
• This standard technically aligns with PNS 01:Part 4:1998, offering specifications and applications for V-belt drives, but it does not cover manufacturing specifications.

V-Belts and Pulleys Standard: Scope

• This Standard provides specifications and technical information for proper application of V-belts and pulleys for drives of agricultural machinery.

Definitions of Terms

• V-belt: A flexible machine element that features a trapezoid shape. It transmits motion and power between two shafts.
• V-pulley: A wheel that has grooved rims and transmits motion and power using one or more V-belts. The cross section of its grooved rim has an open-channel shape.
• V-belt drive: A power transmission device containing one or more V-belts installed on two or more V-pulleys.
• Pulley diameter: The outside diameter of the pulley.
• Pulley pitch diameter: The diameter of the pulley that coincides with the belt pitch.
• Belt pitch: The region in the belt maintains the same length when bent perpendicular to its base.
• Belt length: Length of the belt at its pitch level.
• Speed ratio: The ratio of the pulleys' angular velocities, without considering slip and creep.
• Belt speed: The linear speed of the belt at the pulley pitch diameter level.

Belts: Nomenclature and Dimensions

• Dimensions of V-belts are designated as bb for the top width of the belt and hb for the height of the classical V-belt.
• Nominal dimensions of belt cross-sections for agricultural machines are shown in Table 1.

V-Belt Specifications

• V-belts specifications are in Table 1, and it contains the ranges for different types of cross section and their power range in watts.
• Type A: bb=13 mm, hb=8 mm, power range is 186-1,457 watts
• Type B: bb=16 mm, hb=10 mm, power range is 746-18,642 watts
• Type C: bb=22 mm, hb=13 mm, power range is 11,186-74,570 watts
• Type D: bb=32 mm, hb=19 mm, power range is 37,285-186,425 watts
• Type E: bb=38 mm, hb=25 mm, power range is 74,570 and up watts
• Belts of a given cross-section should operate interchangeably in standard grooves of the same cross-section but belts of different manufacturers should never be mixed on the same drive.

V-Belt Materials and Marking

• V-belts are constructed of cords (cotton, rayon, synthetic, or steel) and fabric impregnated with rubber.
• The V-belt should be marked with its cross section type, pitch length, and manufacturer's name/trademark.
• The packaging should be marked type of cross section, pitch length, and manufacturer's name, trademark, and address.

V-Pulleys: Types and Nomenclature

• V-pulleys can be single-grooved or multi-grooved.
• Dimensions include the top width of the pulley groove (bg), pulley pitch diameter (D), pulley outside diameter (Do), bore diameter(d), hub length (l), height of the pulley groove (hg), and groove angle(α).
• The table includes X, which is one-half the difference between outside diameter and the pitch diameter

V-Pulley Specifications

• Specifications for V-pulleys are shown in Table 2.
• The minimum pulley diameters are recommended, and the recommended ratio (l/d) should be at least 1.5.
• Type A: minimum is 65 mm
• Type B: minimum is 115 mm
• Type C: minimum is 175 mm
• Type D: minimum is 300 mm
• Type E: minimum is 450 mm

V-Pulley Materials

• V-pulleys are generally made of cast iron, cast steel, or pressed steel.
• Cast materials have good friction and wear characteristics.
• Pressed steel pulleys are lighter but may have lower friction, leading to excessive belt wear.

V-Pulley Marking

• The pulley should be marked with its cross section type, pulley diameter, and manufacturer’s name/trademark.
• The packaging should be marked with its cross section type, pulley diameter, and manufacturer’s name, trademark, and address.

Pulley Diameters and Length Calculations

• Use larger pulley diameters to lower bearing loads and allow for smaller belt cross-sections. Conform to minimum recommended pulley diameters in Table 2.
• For a two-pulley drive, the approximate belt length can be calculated using a specified formula (Eq. 1) that involves the length of the belt, the distance between centers of pulleys, and the pitch diameters of the large and small pulleys.
• If the calculation results in length is not of a standard size, use the next longer standard length and correct the center distance using a specified formula (Eq. 2).
• To determine belt length when more than two pulleys are used, lay out the pulleys to scale and sum the tangents and connecting arcs around pulley diameters.
• The length of the connecting arcs can be calculated by the formula Dx A/115 (Eq. 3), where D is the pulley diameter and A is the angle the arc of belt contact on the pulley subtends.

V-Belt Selection and Loading Factors

• V-belt selection should be based on the load’s nature, drive unit type, horsepower rating, pulley sizes, and driving/driven unit speeds.
• Tables 3-7 are guidelines for power transmitted by one belt with velocity and pulley size.
• Correct for loading using service factors (Table 8) because V-belts are used on different machines.
• To obtain horsepower capacity, multiply the driving unit's rated horsepower by the recommended service factor.

Correction for Arc of Contact

• Use Table 9 to correct for arc of contact when using a small pulley; the arc is given by the approximate formula as follows: Arc of contact = 180 – 60(DL – Ds)/C (Eq. 4).
• DL= diameter of the large pulley
• Ds= diameter of the small pulley
• C = center distance of drive.

Belt Length and Correction Factor

• Since short belts experience load more often, their lifespan is shorter versus long belts.
• To achieve a proper belt drive design, adjust for belt length using the belt-length correction factors in Table 10.

Corrected Power Rating

• Corrected power is the product of the power rating, arc contact factor, and belt length correction factor. Assume a belt length correction factor of 1 (Table 10).

Number of Belts for Multiple Drives

• Divide a drive's power capacity (section 7.3.2) by the corrected power rating (section 7.6) to find the number of belts for multiple belt drives.

Idlers

• Use idlers for take-up or to increase the arc of contact; locate them on the slack side.
• An idler should rotate perpendicular to the belt strand and have a strong mounting.
• Idlers can be grooved or flat (Figure 6).
• Use grooved idlers as inside idlers, placed close to the large pulley, and use flat idlers as either inside or outside idlers (Figure 7).
• Table 11 gives the minimum recommended diameters for idlers.

Pulley Diameters

• Table 11 specifies the diameter of flat inside/outside idler based upon the cross section.
• The minimum face width for the flat idler based upon cross section is also in the table.
• The smallest flat idler is 25 mm, while the highest is 51 mm.
• Grooved idlers used, groove dimensions must be like those in Table 2

Safety Recommendations

• Enclose the drive
• Inspect belts regularly for wear and tightness, plus inspect keys and setscrews for tightness periodically.
• Use belts with proper markings, and use proper keys as specified in PAES 304:2000.

V-Belt Drive Selection: Given Parameters

• Split-phase motor is driving a rotary pump.
• Motor runs at 1,750 rpm.
• Pump should run at approximately 1,175 rpm.
• Center distance limit: 1,118 mm.
• Driven pulley diameter limit: 292 mm.
• Need to determine: pulley diameters, belt size, and belt quantity.

Power, Belt, and Pulley Selection

Design Power and Belt Section

• Design power is the nameplate rating multiplied by the recommended service factor from Table 8. Design Power = 1.3 x 7,450 W = 9,685 W.
• Belt section should be section B (from Figure 5).

Pulley Size

• Size of the driven pulley is 280 mm. Ds = DL (nL/ns) Ds= Pitch diameter of the small pulley, mm DL= Pitch diameter of the large pulley, mm nL = number of revolutions of the large pulley, rpm ns = number of revolutions of the small pulley, rpm
• The diameter of the small pulley can be caculated by using the following information Ds = 280 mm (1,175 rpm / 1,750 rpm) = 188 mm
• The limit for center distance is 1,118 mm, center distance formula (1,000 mm is used temporarily), can be determined so that the approximate belt length is known using the following knowns: (1,000 mm, 280 mm+188 mm 2 ). This formula is approximately [L = 2C + *π+(DL+Ds)+ ((DL-Ds) / 4C)]

Correct Center Distance

• Calculate correction for center distance. Since the obtained length isn't standard, you need to select a length from manufacturer stock and correct the center distance with a formula (The square root of b√b−32(DL-Ds)² all over sixteen) .
• • b = 4Ls - 6.28(DL+Ds)
• Ls = Standard Length

Belt Speed and Ratio, Power Rating, and Arc of Contact

• Belt speed (V) is computed V=xD,x Ns, and then diving all of that by 1000 gives a result of ((Pi)*188 x 1,750), which is dividied by 1000 to give result in value in M/min
• Speed ratio = NS, then dividing that by Nl, with Ns = 1,750 and NL= 1,175, gives a result of 1.48
• Power rating is determined by using velocity and small-pulley diameter, the closest power rating of the belt from Table 4 for Section B V-belts is given ( table rating + additional power) per speed ratio = 6,174 all added to 433 yields a result of 6,607 W/belt
• Arc of Contact has this formula Arc of Contact = 180 / then subtract out the quanity (60 (280x188)/1000)), the result is a arc of contact value, if the arc of contact with the table and its parameter given (above) is ≈174.78 degrees, the arc of contact of the correction factor is 0.98 in Table 9

Final Calculations

Corrected power = product / quantity (power rating, services' factor arc, contact correction factors and length correction factor)

• For obtained Length, if belt correction factor is 1.00 (Table 10) then the corrected power = (66.67 watts x quantity (0.98x 1.00) and yields 6,475 W/belt
• Number of needed belts are the Number of Belts by the formulaPower capacity then dividing out ∴ by this Corrected power ratings = 1. 496 ≈ 2 belts

Final Determination

• Therefore 2 section B belts for this are used.

Philippine Agricultural Engineering Standard PAES 302:2000

• This standard specifies and provides technical guidance/data on flat belts and pulleys for agricultural machinery drives.

Flat Belts and Pulleys Standard: Scope

• This standard provides specs, applications, and data for flat belts and pulleys on ag machinery drives.

PAES 304:2000 Keys, Reference, & Application

-PAES 304:2000, Engineering Materials - Keys and Keyways for Agricultural Machines, The above is a list which provides provision and standards that are given in the text, it forms various provisions of the standard itself

• Flat Belts are commonly very flexible and can be used on long centers, they can transmit power w/ quarter twist on drives

Definitions of Terms

• Flat belt: Belts transmitting rotary motion/power between two shafts.
• Flat belt pulley: Used to transmit power by belting it along and across flat pulleys.
• Flat belt drive: Device transmits motion/power between 2 shafts, including the flat pulley.
• Pulley diameter: The outside diameter of the pulley.
• Belt length: Stretched-out length of the belt.
• Speed ratio: Ratio of angular velocities of the pulleys, without considering slip/creep.
• Belt speed: Linear speed of the belt, calculated by using the value of Pi and multiplying it by the ratio of rpm/diameter for the driver pulley.

Flat Belts: Materials

• Flat belts for agricultural machinery are usually made of rubberized cord and fabric, with reinforced nylon cords.
• Flat belts may be spliced to get the desired loop size (also obtainable in a continuous loop), they can also be layered.

Rubberized Fabric Composition, Specs, & Nomenclature

• Fabric or cord is bound and imbued w/ vulcanized rubber compounds, creating rubber belting.
• Advantages: High tensile strength, able to keep metal fasteners, and deter moisture damage; good for weather/steam.
• Table 1 specifies rating (watts per millimeter of belt width) per the rubber and plies used, while Table 2 specifies diameters of rubber belts, and Table 3 specifies minimum/ maximum number of plies is Rubberized,
• Flat belts are designated with width (W) and thickness (t).

Flat Pulleys and Classification

• Shall classify प प in solid and split, w/ 4 categories by shape symbols.
• Table symbols: Solid = Sd , Split = St, Crown = C, Level = L

Flat Pulley Materials and Specs

• Flat Pulleys made from Iron and Fabric
• In Specifications, Nominal width(B) is about same as belt width carried. * Allowance is made to allow the belt ∴ stay’s Min Pully Diameter listed in chart 2
• 2mm below 305 = 25-51 allowance, normal pulley diameter is 1% (h)width-Dimensions in chart 10 • Belts center them in a plane and axis

Flat Pulley Marking

• In Marking section the following need be engraved (Pulley, Diameter and width, and Manufacturer Trademark)
• In Packaging, all from line above and Trademark address

Recommended Design Practices

• Rubber can be use in #2 charts by proper design of of diameter, pulley (Table 2), #7 specifies what pulleys of nylon should be used

Belt Selection and Calculations

• The type of rubber belt and number of ply can be determined by using Table 2 with the belt speed and pulley diameter.
• Selection chart is good in the belting itself, to know it's cross selection, In Figure 2 select chart, determine belts; To get endless, longer stand length, & correction calculate.

Belt Length Calculations

• Calculate Length approximately, in “open two-pulley drive" in the equation shown- with the belt length, distance between centers of pulleys, large pulley diameter (L) & small pulley diameter being the parameters

Continued: Length Calculation

• The next calculation is belt related and a center distance, from an equation; a + b+ -2^ (D+ D)2= (where b+ =4168-6273 +D)- To determine Belt lengths, place it so a new best on the position and their scale as before, a connecting are can then calculate this using the formula

Correction for Arc of Contact & Power Rating

• Table ll shows pulley in a formula such as contact=180-60D (5) in drive w is important to get accurate numbers
• Use data in 4-6 and do math, the width/millimeter equation is: K (8) c
• W= Belt with millimeters
• HS = to be placed
• K=w/m from chart (Table1, Table 11)

Tables and Materials

• Tables show factor of C, a 11 ratio if needed
• A chart has numbers shown in different ratings