Can A Belt Tensioner Be Repaired

Belt Tension

Chugalug tension at steady state can be calculated as:(half dozen.6)Tb=one.37×f×L×m×ii×mi+2×mb+mm×cosδ+H×one thousand×mmwhere Tb is the belt tension (N), f is the coefficient of friction, L is the conveyer length in meter divided by ii, grand is the acceleration due to gravity (9.81m/s2), mi is the load of idlers within 1m length of conveyer belt (kg), mb is the load of 1m length conveyer chugalug (kg), mm is the load of the conveyed materials per meter length of conveyer belt (kg), δ is the inclination angle of conveyor belt (caste), and H is the vertical elevation of conveyor chugalug (grand).

From: Sensing and Monitoring Technologies for Mines and Chancy Areas , 2016

Flexible Intermediate Drives

R Keith Mobley , in Institute Engineer's Handbook, 2001

58.iv.i Belt noise

Belt noise can take the class of squeals and squeaks or chirps, both of which are generally more than abrasive than damaging. Noise ordinarily occurs with all types and makes of belts. Because of this, maintenance people often regard them equally an operational noise and do non show much concern.

Important: Squeals and squeaks are not corrected by applying grease or oil to the surface of belts. This can cause serious belt damage!

Squeals

Although squeals are annoying and will not cause firsthand harm to the belts, it does bespeak that there may be a problem and, therefore, they should not be ignored. The following are some of the causes of belt squealing.

•

Insufficient chugalug tension. This is a common cause and if squealing persists later belts are tensioned correctly, the drive itself should be examined for overloading.

•

Motors operating nearly or at full load

•

Motor dispatch

•

Misaligned idler pulley

•

Dry and dusty belts

Squeaks

The post-obit are some of the reasons for chugalug squeaking, which is often described as sounding like a bird chirping:

•

Dry bearing

•

Belts working in a dusty environment

•

Misaligned idler pulley

Contamination

Common sources of belt contamination are dirt, oil, and grease, all of which should exist removed from belts and pulleys. Dirt accelerates chugalug wear and chugalug traction is impaired when dirt is allowed to build up.

Practise not expose belt drives to oil or grease nether any circumstances! Potential sources of oil and grease include leaking bearings, which should exist repaired immediately. Information technology is important to avoid over-applying lubricants to bearings, but note that nether-awarding tin can contribute to early on failure with resulting damage to belts due to friction build-upward and drag. If oily conditions cannot exist avoided, special oil-resistant belts should be used.

Belt damage

Types of chugalug impairment to watch for are cracking, which can be caused by excessive heat and dust; stretching; added load damage; and damage as a result of belt whipping.

Bully Nifty can be acquired past exposure to loftier temperature and/or dust. Groovy on the bottom sections of belts does non cause a loss of strength or operating efficiency, but can lead to eventual failure. Nevertheless, at that place is no need to supercede belts merely because bottom groovy has been detected.

Extreme heat In the manufacturing process, belts are cured with scientifically controlled rut for given periods of time. If standard belts are operated below 140°F, their materials of construction are not affected. Still, at temperatures higher up 140°F, over-curing will occur and chugalug life will be shortened. Therefore, the utilise of standard V-belts above this temperature should be avoided. Often, acceptable shielding between the heat source and belts can be provided.

Dust Dust can be very detrimental to belts and is often responsible for bottom cracks. The furnishings of dust can exist slowed down greatly and possibly eliminated by installing larger pulleys and larger reverse idler pulleys.

Added load impairment Added loads shorten effective belt life. Always bank check to see if any other load has been added to the belt drive since original installation. Figure 58.nine illustrates the possible effects an added load may have on the motor belt life.

Figure 58.9. Added load

Stretching All belts stretch, giving the appearance of flopping up and downwardly when running. When this occurs, check bearings to ensure that they are free to plow and that at that place is no overload resulting from obstructions. Also check for pulley clothing; worn pulleys create the impression that the belts are too long.

Effigy 58.10. Chugalug whipping

Excessive belt whip Excessive chugalug whip is usually more than common on long-center applications (applications where the distance betwixt the two pulley shafts is great). Pulsating loads in the bulldoze organization tin produce this phenomenon. Damage to the system is oft in the form of chugalug breakage and/or bearing failure. Chugalug whip can be corrected past installing an idler pulley to dampen the vibration.

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Applied mechanics

J. Carvill , in Mechanical Engineer'southward Data Handbook, 1993

ii.two.1 Flat, vee and timing chugalug drives

Formulae are given for the power transmitted by a belt drive and for the tensions in the belt. The effect of centrifugal force is included.

A table of information on timing belt drives is included.

Symbols used:

F ₁ = belt tension, tight side

F _two = chugalug tension, slack side

r _a = radius of pulley a

r _b = radius of pulley b

North _a = speed of pulley a

North _b = speed of pulley b

m = mass of belt per unit length

P = power transmitted

μ = coefficient of friction betwixt chugalug and pulley

F _o = initial belt tension

θ_a = arc of belt contact pulley a

θ_b = arc of belt contact pulley b

L = distance between pulley centres

due south = percentage sideslip

five = belt velocity

Speed ratio $\frac{N_a}{{\mathrm{Northward}}_b}=\frac{r_b}{r_a}\frac{\left(100-s\right)}{100}$

(when pulley b is the driver)

Arc of contact (r _a r _b):

${\theta }_a={180}^{°}+2{\sin -}^{-1}\frac{\left(r_a-r_b\right)}{\mathrm{Fifty}}$

${\theta }_b={180}^{°}-2{\sin -}^{-\mathrm{ane}}\frac{\left(r_a-r_b\right)}{\mathrm{Fifty}}$

Tension ratio for belt about to slip:

For pulley 'a'

$\frac{F_{\mathrm{ane}}}{F_2}=e^{\mu {\theta }_a}$

For caster 'b'

$\frac{F_1}{F_2}=e^{\mu {\theta }_b}$

where: due east = base of operations of natural logarithms (= ii.718).

Power chapters P = v(F ₁ – F ₂)

where: belt velocity five = 2πr _a North _a = 2πr _b North _b (no skid).

Pulley torque T _a = r _a(F ₁ – F _two); T _b = r _b(F ₁ – F ₂)

Initial tension $F_0=\frac{\left(F_1+F_2\right)}{\mathrm{ii}}$

Effect of centrifugal force: the chugalug tensions are reduced past mv ² so that

Vee belt

The 'wedge' activeness of the vee belt produces a higher effective coefficient of friction μ^'

where: α = the 'half angle' of the vee (μ^' = 2.9μ for α = 20°).

Timing belts

Timing belts have teeth which mate with grooves on the pulleys. They are reinforced with loftier forcefulness polymer strands to give power capacity up to three times that of conventional belts at three times the speed. There is no slip so a abiding ratio is maintained. A large number of speed ratios is available. Belts are made in several strengths and widths.

Timing belt sizes (BS 4548: 1970)

Blazon	Meaning	Pitch (mm)	Widths (mm)	Abiding, Grand
Twoscore	Extra low-cal	five.08	6.4, 7.ix, nine.6	—
L	Light	9.53	12.7, nineteen.one, 25.4	1.53
H	Heavy	12.lxx	19.1, 25.4, 38.1, 50.viii, 76.two	5.19
XH	Actress heavy	22.23	50.viii, 76.2, 101.6	12.60
XXH	Double extra heavy	31.75	50.8, 76.2, 101.half-dozen, 127.0	—

Service factor

Hours of service per day		<ten	10–16	>xvi
% full power		100	72	67
Form	Applications				% full ability
one	Typewriters, radar, light domestic				100
two	Centrifugal pumps, fans, woodworking machines, light conveyors				69
3	Punching presses, large fans, printing machines, grain conveyors				63
4	Blowers, newspaper machines, piston pumps, textile machines				58
5	Brickmaking machines, piston compressors, hoists, crushers, mills				54

Ability capacity P = KNTW × 10^–six kilowatts

where:

K = size constant (encounter table)

Due north = number of revolutions per minute

T = teeth in smaller pulley

West = width of belt (mm)

Instance: Type H belt, W = 50.8 mm, Due north = 1500 rev min⁻¹, T = 20, for large fan working 12 hours per solar day. From tables, Chiliad = 5.19 service factors 72% and 63%.

P = 5.19 × 1500 × twenty × l.eight × x⁻⁶ × 0.63 × 0.72 = three.59 kW

Note: at high speeds and with large pulleys the ability capacity may be upwards to 25% less. See manufacturer's tables.

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Friction, lubrication and wearable in lower kinematic pairs

T.A. STOLARSKI MSc, PhD, DSc, DIC, CEng, MIMechE , in Tribology in Car Design, 1990

4.10.iii. Power manual rating

In judge calculations information technology is usual to presume that the initial belt tension is equal to the mean of the driving tensions, i.e.

(4.ninety) $T_{\text{m}}=T_0=\frac{1}{2}\left(T_1+T_2\right).$

If the belt is on the point of slipping, and the effects of centrifugal activeness are neglected

$\frac{T_{\mathrm{one}}}{T_2}={\text{e}}^{fx},$

where α is the angle of lap of the smaller pulley. Hence

${\begin{array}{lll}{T}_{\mathrm{ii}}=2T_0-T\hfill & \text{and}\hfill & T\hfill \end{array}}_1-T_2=2\left(T_1-T_0\right).$

If 5 = the mean belt speed in ms⁻¹,

(4.91) $\begin{array}{c}\text{power}\text{transmitted=}\left(T_1-T_2\right)V\\ =2\left(T_1-T_0\right)V.\end{array}$

Alternatively:

$2T_0=T_1+T_{\mathrm{ii}}=T_{\mathrm{ii}}\left({\text{e}}^{fx}+\mathrm{ane}\right)$

and

$\begin{array}{c}{T}_1-T_2=T_2\left({\text{eastward}}^{fx}-\mathrm{i}\right)=2T_0\frac{{\text{east}}^{fx}-\mathrm{one}}{{\text{due east}}^{fx}+1}\\ \text{power}\text{transmitted}=2T_{0}V\frac{{\text{eastward}}^{f\mathrm{10}}-\mathrm{one}}{{\text{east}}^{f\mathrm{ten}}+\mathrm{ane}}.\end{array}$

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Developments in ring spinning

R.Southward. Rengasamy , in Advances in Yarn Spinning Technology, 2010

7.4.2 Delayed starting time-upwards of drafting rollers

The drive for the drafting rollers is a rigid one (past gears) and the spindle is driven past a flexible bulldoze (belt). The initial belt tensions on both sides of the spindle are the same while the machine is at rest. When the band-spinning machine is started, the chugalug tension in the forrard management increases, and at the dorsum it decreases enough to build up the required torque on the spindle. Additional slackness nowadays on the spindle belt compounds the problem. The acceleration of the spindle lags backside that of the drafting rollers and the yarn slackens; if it slackens as well much, this might atomic number 82 to balloon instability and the end breaks. Delaying the starting of the drafting rollers by a few seconds would solve this problem. In the Marzoli ring-spinning machine, at the beginning of cop build-up, the starting of the drafting rollers is delayed so that the spindle starts to rotate first, which tightens the initial yarn ends ( Marzoli, 2009).

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Granulators

John R. WagnerJr., ... Harold F. GilesJr., in Extrusion (Second Edition), 2022

Proper granulator preventive maintenance to ensure that a long granulator life includes the following:

•

Grease the rotor bearings as recommended by the manufacturer.

•

Check the belt tension regularly, retensioning the belts as required.

•

Keep the regrind clean.

•

Routinely bank check rotating blade and bed knife wear.

•

Replace blades or bed knives on a routine schedule or as required, based on the materials being granulated.

•

Sharpen knives to the proper angle.

•

Check all safety switches and interlocks to verify that they are operating properly.

•

Keep a maintenance record of all work and role replacement.

Review Questions

1.

What are the different rotor designs used in granulators?

2.

What determines the size of the granulated particles?

3.

Where are granulators used in extrusion?

iv.

What are four maintenance issues associated with granulators?

5.

What needs to be checked and serviced in a skilful preventive maintenance program for granulators?

6.

What is the deviation between a granulator used to regrind picture compared to a granulator designed to regrind profiles, pipe, and heavy stock?

7.

What are the differences in knives required for different resins?

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Vibration Monitoring and Analysis

R Keith Mobley , in Establish Engineer's Handbook, 2001

Five-belt intermediate drives

Electrical motors with V-belt intermediate drive brandish the aforementioned failure modes as those described previously. Nevertheless, the unique V-belt frequencies should be monitored to determine if improper belt tension or misalignment is evident.

In addition, electric motors used with V-belt intermediate drive assemblies are susceptible to premature article of clothing on the bearings. Typically, electrical motors are not designed to compensate for the sideloads associated with Five-belt drives. In this blazon of application, special attending should be paid to monitoring motor bearings.

The primary data-measurement point on the inboard bearing housing should be located in the plane opposing the induced load (sideload), with the secondary point at 90°. The outboard primary data-measurement point should be in a plane opposite the inboard bearing with the secondary at xc°

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Major Procedure Equipment Maintenance and Repair

In Practical Mechanism Direction for Process Plants, 1997

Tensioning V-Belt Drives

Without exception, the most important factor in the successful operation of a Five-belt drive is proper chugalug-tensioning. To achieve the long, trouble-free service associated with V-belt drives, chugalug tension must be sufficient to overcome slipping under maximum superlative load. This could be either at the start or during the work cycle. The amount of tiptop load will vary depending upon the graphic symbol of the drive automobile or drive system. To increment total tension, simply increase the eye distance. Before attempting to tension any drive it is imperative that the sheaves be properly installed and aligned. If a V-belt slips information technology is too loose. Add to the tension by increasing the center distance. Never employ belt dressing as this volition damage the belt and cause early failure.

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Power losses prediction in poly-v belt transmissions: application to front engine accessory drives

L. Manin , ... C. Lorenzon , in International Gear Briefing 2022: 26th–28th August 2022, Lyon, 2022

2.i.three.2 Radial pinch losses

As it is illustrated in figure 6, when the belt is lying inside, the belt is nether a radial compression P_v which is generated by the flank pressure P_f . Information technology assumes that the cord layer takes the most belt tension. So information technology is obviously that the material, which is betwixt the cord layer and the rib (middle layer), is under the effect of radial compression, the thickness of this part is H _b. However, when the belt is lying outside, it is the top layer of the belt that is under radial pinch, its thickness is H_t.

When the belt is lying inside the radial strain is given by P_v/Yard_b, with One thousand_b the radial stiffness. The power loss is then obtained by:

(twenty) $\mathrm{\Delta }{\mathrm{P}}_{\mathit{h}\_\mathit{rc}}=\left[\mathrm{\pi }\left({\mathrm{a}}_2\frac{{\mathrm{P}}_{\mathit{v}}}{{\mathrm{K}}_{\mathrm{b}}}+{\mathrm{b}}_2\right){\left(\frac{{\mathrm{P}}_{\mathit{5}}}{{\mathrm{K}}_{\mathrm{b}}}\right)}^2\right]\mathrm{B}.{\mathrm{H}}_{\mathrm{b}}\ast \mathrm{R}.\mathrm{\omega }$

Amidst the outputs of the dynamic beliefs simulation software, we accept the flank pressure P_f, thus the radial pressure tin can be found by:

(21) $\mathrm{Pv}=\frac{2.{\mathrm{P}}_{\mathit{f}}.{\mathrm{H}}_{\mathit{c}}.tan\frac{\mathrm{\alpha }}{2}}{\mathrm{L}}$

When the belt is lying outside:

(22) $\mathrm{\Delta }{\mathrm{P}}_{\mathit{h}\_\mathit{rc}}=\left[\mathrm{\pi }\left({\mathrm{a}}_1\frac{{\mathrm{P}}_{\mathit{v}}}{{\mathrm{G}}_{\mathrm{b}\_\mathrm{Ht}}}\right){\left(\frac{{\mathrm{P}}_{\mathit{v}}}{{\mathrm{K}}_{\mathrm{b}\_\mathrm{Ht}}}\right)}^2\right]\mathrm{B}.{\mathrm{H}}_{\mathrm{t}}.\mathrm{R}.\mathrm{\omega }$

where Yard_{b_Ht} is the radial stiffness of the peak layer. The power loss is but for one caster whose flank pressure is P_f. In the case of a multi pulley transmissions, a specific value is used for each pulley, and these values are taken from the dynamic simulation results.

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Belts and rope drives

N. Gokarneshan , ... C.B. Senthil Kumar , in Mechanics and Calculations of Textile Machinery, 2022

one.9 Comparison of flat and 5-belts

The advantages of apartment belts in comparison to V-belts are listed beneath:

(one)

They are elementary in design and are relatively cheap.

(2)

They can be hands maintained in terms of periodic aligning of belt tension and their replacement when worn out.

(iii)

Precise alignment of pulleys and shafts is non so critical.

(four)

They requite better protection to the mechanism against bear on or overloads. As they are flexible and long, they have the ability to absorb shock and vibrations due to slipping action.

(v)

Clutching action with apartment belt is possible by moving it from fast to loose caster and vice versa. This type of arrangement is commonly found in old blow rooms, cards, draw frames and speed frames.

(6)

Using cone pulleys, different velocity tin be obtained for the driven chemical element by moving the apartment belt axially.

(7)

They can be used for long distances, even upwards to 15 thousand, where other types of drives cannot exist used.

The major advantages of Five-belt are as follows:

(1)

Five belts are used for short distance, which results in compact construction.

(2)

Due to wedge action between the chugalug and the caster, the slip is less.

(3)

Wedging action permits a smaller arc of contact, increases the pulling capacity of the chugalug and consequently results in an increase in the ability transmission capacity.

(iv)

They can exist used for loftier-speed reduction up to 7:i.

(5)

They tin be operated fifty-fifty when the belt is vertical.

(6)

They are made available in endless grade, which results in smooth and quite operation, even at high speeds.

The major disadvantages of Five-belts are as follows:

(i)

The structure of Five-grooved pulleys is complicated and costlier compared to the pulleys for flat belt drives.

(2)

The creep in V-belts is higher compared to flat belts.

(three)

The ratio of thickness of V-belts to pulley diameter is loftier, which increases the angle stress in the chugalug cross-department and adversely affects its durability.

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Formation of Digital Mine Using the Net of Things

S.K. Chaulya , One thousand.M. Prasad , in Sensing and Monitoring Technologies for Mines and Chancy Areas, 2022

6.13.2 Production Monitoring

Real-time product monitoring of coal/mineral tin can be ascertained with the assistance of an integrated programmable logic controller organisation using a software (Mandal et al., 2022). It is calculated based on tensile load on conveyer belt carrying coal.

Chugalug tension : A conveyor belt always experiences a tensile load due to rotation of electric bulldoze, weight of the conveyed materials and idlers. Belt tension at steady state tin be calculated as:

(six.6) $T_{\mathrm{b}}=1.37\times f\times \mathrm{Fifty}\times \mathrm{one\; thousand}\times \left[\mathrm{ii}\times {\mathrm{thousand}}_{\mathrm{i}}+\left(2\times m_{\mathrm{b}}+m_{\mathrm{m}}\right)\times cos\delta \right]+\left(H\times \mathrm{thousand}\times m_{\mathrm{m}}\right)$

where T _b is the chugalug tension (N), f is the coefficient of friction, L is the conveyer length in meter divided by two, g is the acceleration due to gravity (9.81   m/s²), m _i is the load of idlers within 1   m length of conveyer belt (kg), m _b is the load of 1   m length conveyer belt (kg), yard _{one thousand} is the load of the conveyed materials per meter length of conveyer belt (kg), δ is the inclination angle of conveyor belt (degree), and H is the vertical height of conveyor belt (m).

Power to drive pulley: The power required to drive pulley can exist calculated from the belt tension value equally:

(6.7) $P_{\mathrm{p}}=\left(T_{\mathrm{b}}\times v\right)/\mathrm{grand}$

where P _p is the power to drive pulley (KW), T _b is the belt tension (N), and v is the belt speed (m/s).

Belt tension while starting the system: Initially during the start of a conveyor system, tension in the chugalug is much higher than the tension in steady state. Belt tension while starting tin be calculated as:

(vi.eight) $T_{\mathrm{b}\mathrm{s}}=T_{\mathrm{b}}\times {\mathrm{Thou}}_{\mathrm{south}}$

where T _bs is the Chugalug tension while starting the organisation (Northward), T _bs can be measured using chugalug tension measuring instrument (Trumeter), and One thousand _s is the start-upward gene.

To determine the One thousand cistron, different informations are required, namely (i) belt wrap at drive, (ii) bare steel pulley or lagged caster, and (iii) screw take-upwards or gravity take-upwardly. The K factor, equally can be seen from the following expression:

(half dozen.nine) $\mathrm{One\; thousand}=\frac{1}{{\mathrm{eastward}}^{fQ}-\mathrm{ane}}$

where e is the base of Naperian logarithm   =   2.718.

The K factor is dependent upon coefficient of friction (f) between the pulley surface and belt surface and wrap (Q) of the chugalug around the pulley with Q measured in radians.

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Can A Belt Tensioner Be Repaired,

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