V-Belts and Pulleys for Agricultural Machinery
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Questions and Answers

A V-belt with a top width ($bb$) of 16 mm and a height ($hb$) of 10 mm is classified as what type?

  • Type A
  • Type D
  • Type C
  • Type B (correct)

A manufacturer is producing V-belts designed to transmit power in the range of 25,000 watts. Which cross-section type is MOST suitable for this application?

  • Type D
  • Type C (correct)
  • Type B
  • Type A

What materials constitute the primary components of a V-belt's construction?

  • Plastic and nylon
  • Wood and metal
  • Leather and adhesive
  • Cords (cotton, rayon, synthetic, or steel) and fabric impregnated with rubber (correct)

Which piece of information is required to be marked BOTH on the V-belt itself AND on its packaging?

<p>Type of cross section and pitch length (C)</p> Signup and view all the answers

A V-belt manufacturer marks only their name on the belt, what is missing?

<p>Type of cross section and pitch length (C)</p> Signup and view all the answers

When should V-belts from different manufacturers be mixed on the same drive system?

<p>Never (B)</p> Signup and view all the answers

Given a V-pulley system, what does the ratio l/d ≥ 1.5 refer to, according to recommended specifications?

<p>Ratio of belt length to pulley diameter (B)</p> Signup and view all the answers

A V-belt drive system requires a power transmission capability exceeding 74,570 watts. Which V-belt type should be selected?

<p>Type E (B)</p> Signup and view all the answers

How is the number of belts to be used in multiple belt drives determined?

<p>By dividing the power capacity of the drive by the corrected power rating. (D)</p> Signup and view all the answers

Using Table 10, what is the belt correction factor for a B-type belt with an outside length designation of 97?

<p>1.02 (D)</p> Signup and view all the answers

According to Table 10, which belt type has an outside length of 3,154.68?

<p>C (C)</p> Signup and view all the answers

Based on Table 10, which of the following belt types is available with a length designation of 26?

<p>A (B)</p> Signup and view all the answers

What is the belt correction factor for an A-type belt with a length designation of 60, according to Table 10?

<p>0.98 (D)</p> Signup and view all the answers

For which of the following length designations does Table 10 provide belt length and correction factor data for all five belt types (A, B, C, D, and E)?

<p>180 (C)</p> Signup and view all the answers

What is the purpose of idlers in agricultural belt drives?

<p>To provide take-up or increase the arc of contact. (C)</p> Signup and view all the answers

If a belt drive requires both take-up and an increased arc of contact, what component might be necessary?

<p>Idlers (B)</p> Signup and view all the answers

Using Table 10, identify the belt type and length designation combination with an outside length of 2,773.68.

<p>C-105 (D)</p> Signup and view all the answers

Based on the information provided, what is the relationship between belt length designation and the belt correction factor?

<p>As the belt length designation increases, the belt correction factor generally increases. (B)</p> Signup and view all the answers

On which side of the drive should an idler be located if one is required?

<p>The slack side, to manage belt sag. (D)</p> Signup and view all the answers

What orientation should the axis of rotation of an idler have in relation to the plane of the belt strand?

<p>Perpendicular, ensuring proper contact. (C)</p> Signup and view all the answers

Where should grooved idlers be placed when used as inside idlers?

<p>Close to the larger pulley to support the belt. (B)</p> Signup and view all the answers

What is the minimum recommended outside diameter for a flat outside idler with a cross-section B?

<p>152 mm (A)</p> Signup and view all the answers

What is the purpose of enclosing a drive with covers?

<p>To reduce noise and prevent foreign material contamination. (C)</p> Signup and view all the answers

What aspect of belts should be inspected on a periodic basis?

<p>Wear and tear, and tightness. (A)</p> Signup and view all the answers

Considering the functional requirement of an idler, which statement is MOST accurate?

<p>Flat idlers can be used in both inside and outside positions. (C)</p> Signup and view all the answers

A belt drive system with a cross-section 'C' belt requires a grooved inside idler and a flat outside idler. What are their minimum recommended outside diameters, respectively?

<p>172 mm and 216 mm (C)</p> Signup and view all the answers

Which of the following combine functions requires the highest correction factor according to the provided data?

<p>Combining cylinders (D)</p> Signup and view all the answers

A belt drive system has a small pulley with an arc of contact of 120 degrees. What is the correction factor that should be applied?

<p>0.82 (C)</p> Signup and view all the answers

Why is a correction factor for belt length necessary in belt drive design?

<p>Shorter belts are subjected to load more frequently. (C)</p> Signup and view all the answers

Which organization initiated the formulation of the Philippine Agricultural Engineering Standard PAES 301:2000?

<p>Agricultural Machinery Testing and Evaluation Center (AMTEC) (D)</p> Signup and view all the answers

What is the primary focus of the Philippine Agricultural Engineering Standard PAES 301:2000 regarding V-belts?

<p>Specifications and proper application of drives using V-belts (C)</p> Signup and view all the answers

What three factors are multiplied together to obtain the corrected power rating of a belt?

<p>Arc correction factor, belt-length correction factor, belt power rating. (D)</p> Signup and view all the answers

A belt drive system has a small pulley with an arc of contact of 157 degrees. If the rated power of the belt is 10 hp, what adjustment should be made based solely on the arc of contact?

<p>Decrease the rated power by multiplying by 0.94. (B)</p> Signup and view all the answers

Which of the following organizations was consulted during the review process of PAES 301:2000?

<p>Philippine Society of Agricultural Engineers (PSAE) (B)</p> Signup and view all the answers

Which of the following best describes the process by which PAES 301:2000 was technically formulated?

<p>Technically formulated in accordance with PNS 01:Part 4:1998. (B)</p> Signup and view all the answers

Given a belt drive system where the small pulley has an arc of contact of 133 degrees, how does this affect the power transmitted compared to a system with 180 degrees of contact, assuming all other factors remain constant?

<p>The power transmitted will be approximately 13% lower. (D)</p> Signup and view all the answers

A belt drive system needs adjustments for both belt length and arc of contact. What sequence of steps ensures an accurate corrected power rating?

<p>Multiply the power rating by the arc correction factor, then multiply by the belt-length correction factor. (C)</p> Signup and view all the answers

Which of the following topics would be considered as within the scope of PAES 301:2000?

<p>Optimal tensioning methods for V-belts in agricultural machinery (C)</p> Signup and view all the answers

In a scenario where a shorter belt is used in a drive system, what countermeasure can be adopted to mitigate the reduction in belt life?

<p>Increasing rated belt power to compensate. (B)</p> Signup and view all the answers

Which of the following is a likely use case for PAES 301:2000?

<p>An agricultural engineer selecting the appropriate V-belt for a specific machine design. (D)</p> Signup and view all the answers

ISO 3410:1989 is listed as a reference in the standard. What is the focus of this standard?

<p>Agricultural Machinery – Endless variable-speed V-belts and groove sections of corresponding pulleys (B)</p> Signup and view all the answers

Why were comments and reactions from a public hearing considered in the finalization of PAES 301:2000?

<p>To incorporate diverse perspectives and ensure practical relevance. (A)</p> Signup and view all the answers

A belt drive system is being designed. Which of the following considerations would least contribute to the longevity and efficiency of the system?

<p>Using the smallest possible pulley diameters to minimize space requirements. (C)</p> Signup and view all the answers

What primary information is required on both the pulley itself and its packaging according to the standard?

<p>Type of cross section and pulley diameter. (D)</p> Signup and view all the answers

When calculating the center distance (C) using Equation 2, what adjustments should be made if the calculated belt length is not a standard size?

<p>Use the next longer standard length and adjust the center distance accordingly. (B)</p> Signup and view all the answers

In a two-pulley system, if the pitch diameter of the large pulley ($D_L$) is 200 mm, the pitch diameter of the small pulley ($D_S$) is 100 mm, and the distance between centers (C) is 500 mm, what is the approximate belt length (L) according to Equation 1?

<p>Approximately 1657 mm (A)</p> Signup and view all the answers

In a multi-pulley system (more than two pulleys), how should the belt length be determined?

<p>By geometrically laying out the pulleys to scale and summing the tangent and arc lengths. (D)</p> Signup and view all the answers

If a calculated belt length is 1520 mm, but the standard belt lengths available are 1500 mm, 1550 mm, and 1600 mm, which standard length should be selected for calculating the corrected center distance?

<p>1550 mm. (D)</p> Signup and view all the answers

Why is it generally recommended to use larger pulley diameters in belt drive systems?

<p>To lower bearing loads and potentially allow for smaller belt cross-sections. (B)</p> Signup and view all the answers

A pulley is marked with 'A-100'. According to the standard, what does this marking most likely indicate?

<p>The pulley is type A cross-section and has a diameter of 100 mm. (D)</p> Signup and view all the answers

Flashcards

PAES 301:2000

A standard that specifies the proper application of drives using V-belts.

AMTEC

Agricultural Machinery Testing and Evaluation Center.

BAR

Bureau of Agricultural Research.

DA

Department of Agriculture.

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Technical Committee for Study 2

Development of Standards for Engineering Materials.

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PSAE

Philippine Society of Agricultural Engineers.

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NAFC

National Agriculture and Fisheries Council.

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PNS 01:Part 4:1998

Rules for the Structure and Drafting of Philippine National Standard.

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What is 'bb' in V-belt terms?

The top width of a V-belt.

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What is 'hb' in V-belt terms?

The height of a classical V-belt.

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What are the standard top widths (bb) for V-belts?

A: 13 mm, B: 16 mm, C: 22 mm, D: 32 mm, E: 38 mm

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What are the standard heights (hb) for V-belts?

A: 8 mm, B: 10 mm, C: 13 mm, D: 19 mm, E: 25 mm

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What materials make up a V-belt?

Cotton, rayon, synthetic, or steel cords impregnated with rubber.

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What is marked on a V-belt?

Type of cross-section and pitch length, manufacturer information.

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What do V-pulley specifications include?

Minimum pulley diameters.

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What is the recommended minimum ratio for l/d in V-pulleys?

Must be at least 1.5.

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Pulley markings

The type of cross section and pulley diameter and manufacturer’s name or trademark.

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Packaging markings for pulleys

Type/diameter, manufacturer's info (name, trademark, address).

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Benefits of larger pulley diameters

Using larger pulley diameters lowers bearing loads and allows smaller belt cross-sections.

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Belt length formula (2 pulleys)

L = 2C + (π/2)*(DL + DS) + (DL - DS)^2 / (4C)

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Center distance formula

C = (b + sqrt(b^2 - 32*(DL - DS)^2)) / 16

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Ls Meaning

Ls = standard belt length (mm)

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Belt length (multiple pulleys)

Sum of tangents (T) + connecting arcs around pulley diameters.

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Belt length measurement

Arrange pulleys (pitch dia.) to scale to simulate new belt installation for calculating the length of the belt.

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Speed Ratio Power Adjustment

Accounts for extra power needed due to differences in pulley sizes.

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Corrected Power Calculation

Multiply the arc correction factor, belt-length correction factor, and the belt's power rating.

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Belt-Length Correction Factor

Accounts for the reduced lifespan of shorter belts due to more frequent load cycles.

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Arc Correction Factor

Accounts for the contact area between the belt and pulley.

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Power factor when using combine cylinders & corn-sheller cylinders

1.5

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Power factor when using rear cylinder beaters, straw walkers

1.0

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Power factor when using fans, cleaning shoes and sieves

1.0

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Belt Length Impact

Accounts for how many rotations a short belt must endure compared to a longer one.

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Determining Number of Belts

Dividing the power capacity by the corrected power rating gives the number of belts needed.

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Purpose of Idlers

Agricultural belt drives to provide take-up or to increase the arc of contact.

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Another Purpose of Idlers

To increase the arc of contact to obtain the required drive capacity.

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Belt Length Correction Factor Table

Table to look up belt length correction factors based on belt length.

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Take-up Using Idlers

Required on agricultural belt drives to provide take-up

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Table 10

A belt length and belt length correction factor may be found here.

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Idlers

Necessary on agricultural belt drives

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Outside Length

Measurement from outer edge to outer edge of the belt.

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Idlers Necessity

Agricultural belt drives may need these to provide take-up

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Idler placement

An idler should be placed on the slack side of the drive to maintain belt tension.

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Idler axis orientation

The axis of rotation should be perpendicular to the belt strand to ensure proper contact.

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Idler Mounting Strength

The mounting must be robust to maintain alignment and stability.

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Types of Idlers

Grooved or flat; grooved idlers go close to the large pulley as inside idlers.

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Grooved idler placement

Grooved idlers used as inside idlers should be placed close to the large pulley.

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Idler Size Standards

The standards give the minimum outer diameter and face width for different belt cross sections.

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Drive Covers

Using covers minimizes foreign object interference and enhances safety.

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Drive Inspection

Regular inspections help identify wear, tear and/or incorrect belt tightness.

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Study Notes

Overview

  • This standard establishes specifications and provides technical information for the proper application of V-belts and pulleys for drives of agricultural machinery.
  • The standard was technically formulated according to PNS 01:Part 4:1998, focusing on V-belt drive specifications and applications, but excluding manufacturing details.
  • Proper application of drives using V-belts, not covering manufacturing specifications is detailed in this standard.

References

Normative references containing provisions include:

  • PAES 304:2000, Engineering Materials – Keys and Keyways for Agricultural Machines - Specifications and Applications.

V-Belt Drive Applications

  • V-belt drives are commonly used to transmit motion & power to shafts.
  • Used when shafts have short center distances, can operate with small pulley diameters.
  • Multiple V-belts can make a multiple-belt drive when used on a multi-grooved pulley.

Definitions

V-Belt

  • A flexible machine element used to transmit motion & power between two shafts.
  • Cross section is shaped roughly like a regular trapezoid outlined by the base, sides and top of the belt

V-Pulley

  • A wheel with one or more grooved rims used to transmit motion and power by means of one or more V-belts.
  • The cross section of the grooved rim is in the shape of an open-channel outlined by the base and the two slanted sides.

V-Belt Drive

  • A power transmission device consisting of one or more V-belts, mounted on two or more V-pulleys.

Pulley Diameter

  • The outside diameter of the pulley.

Pulley Pitch Diameter

  • The diameter of the pulley, which coincides with the belt pitch.

Belt Pitch

  • The region in the belt that keeps the same length when the belt is bent perpendicularly to its base.

Belt Length

  • The length of the belt at the level of its pitch.

Speed Ratio

  • The ratio of the angular velocities of the pulleys making no allowance for slip and creep.

Belt Speed

  • The linear speed of the belt at the level of the pulley pitch diameter.

V-Belts

Nomenclature

  • Dimensions of V-belts shown in Figure 1, nominal dimensions of belt cross-sections for agricultural machines shown in Table 1. bb - Top width of the belt ht - The height of classical V­belt

V-Belt Specifications

  • Specifications of V-belts are given in Table 1.
  • Belts of a given cross-section should operate interchangeably in standard grooves of the same cross-section.
  • Belts of different manufacturers should never be mixed on the same drive due to different constructions and manufacturing methods. Specifications of V-belts:
  • Type A cross section: bb = 13 mm, hb = 8 mm, Power range = 186-1,457 watts.
  • Type B cross section: bb = 16 mm, hb = 10 mm, Power range = 746-18,642 watts.
  • Type C cross section: bb = 22 mm, hb = 13 mm, Power range = 11,186-74,570 watts.
  • Type D cross section: bb = 32 mm, hb = 19 mm, Power range = 37,285-186,425 watts.
  • Type E cross section: bb = 38 mm, hb = 25 mm, Power range = 74,570 and up watts.

Materials

  • V-belt includes cords like cotton, rayon, synthetic, or steel, and fabric impregnated with rubber

Marking on a V-Belt

  • Type of cross section and pitch length
  • Manufacturer's name, trademark

Marking On Packaging of V-Belt

  • Type of cross section and pitch length
  • Manufacturer's name, trademark, and address

V-Pulleys

Nomenclature

  • V-pulleys are either single-grooved or multi-grooved, dimensions are shown in Figure 2.

Materials

V-pulleys made of:

  • Cast iron
  • Cast steel
  • Pressed steel Cast materials have good friction and wear resistance characteristics Pulleys made of pressed steel are lighter but may have lower friction & cause excessive belt wear

V-Pulley Specification

  • The recommended ratio, l/d shall be at least 1.5.
  • Minimum recommended pulley diameters are indicated in Table 2.

Marking on a Pulley

  • Type of cross section and pulley diameter
  • Manufacturer's name and/or its trademark.

Marking on Packaging of Pulley

  • Type of cross section and pulley diameter
  • Manufacturer's name, trademark and address

Pulley Diameters

  • Larger pulley diameters are better.
  • Using larger pulley diameters results in lower bearing loads.
  • Also can allow using smaller, less expensive belt cross-sections.
  • Should conform to the minimum recommended as specified in Table 2.

Length Calculations

  • For two-pulley drive: L = 2C + (π/2)(DL + Ds) + ((DL - Ds)² / 4C)
  • To determine the belt length when more than two pulleys are used on a drive, the length of the belt shall be the sum of the tangents (T) and the connecting arcs around the diameters of the pulleys.

Design

Selection

  • Selection of a V-belt should be based on nature of the load, type of driving unit, horsepower rating, size of pulleys, speeds of driving/driven units.
  • V-belts are used on different machines, service factors should be used to correct for loading.
  • To obtain the horsepower capacity of the drive, drive's rated horsepower is multiplied by the recommended service factor.

Correction for arc of contact

  • Correction for arc of contact for small pulley is determined from Table 9, arc being given.
    • Arc of contact = 180 - (60(DL - Ds) / C)

Idlers

  • May be necessary on agricultural belt drives to provide take-up or to increase the arc of contact to obtain the required drive capacity
  • Should be located on the slack side of the drive
  • An idler should have its axis of rotation perpendicular to the plane of the belt strand on which it runs.
  • The idler mounting should be strong enough to maintain its relationship at all times.
  • May be grooved or flat.
  • Should have dimensions shown in Table 2 if grooved idlers are needed.
  • Grooved idlers are to be used as inside idlers and should be placed close to the large pulley.
  • Flat idlers are used as either inside or outside idlers.
  • Table 11 specifies the minimum recommended diameters for idlers.

Safety

  • Enclosing the drive with covers is recommended for safety and to avoid foreign materials from getting in contact with the drive
  • Make drive inspection on a periodic basis - inspect belts for wear and tear and for its tightness, tightness of keys and setscrews should also be inspected periodically
  • Use belts with proper markings
  • Use proper keys as specified in PAES 304:2000

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Related Documents

PDF: Engineering Materials - V-belts and Pulleys Specifications and Applications

Description

Specifications and technical details for using V-belts and pulleys in agricultural machinery drives are provided. It is applicable for drives, motion and power transmission to shafts, and for short center distances. Manufacturing details are excluded.

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