SPEED OF BELT IN

FEET

PER MINUTE

Horse-power transmitted for arc of contact of

10°

20

30°

40°

50°

60°

70°

80°

90°

100°

110°

120°

100

0.014

0.028

0.040

0.052

0.062

0.072

0.082

0.090

0.098

0.106

0.112

0.119

200

0.029

0.056

0.080

0.103

0.125

0.145

0.163

0.180

0.196

0.211

0.225

0.237

300

0.043

0.083

0.120

0.155

0.187

0.217

0.245

0.270

0.294

0.316

0.337

0.356

400

0.058

0.111

0.161

0.207

0.249

0.289

0.326

0.360

0.392

0.422

0.449

0.475

500

0.072

0.139

0.201

0.258

0.312

0.361

0.408

0.451

0.470

0.527

0.562

0.594

600

0.086

0.166

0.241

0.310

0.374

0.434

0.489

0.541

0.588

0.633

0.674

0.712

700

0.101

0.194

0.281

0.361

0.436

0.506

0.571

0.631

0.686

0.738

0.786

0.831

800

0.115

0.222

0.321

0.413

0.499

0.578

0.652

0.721

0.785

0.844

0.899

0.950

900

0.l29

0.250

0.361

0.465

0.561

0.651

0.734

0.811

0.883

0.949

1.011

1.068

1000

0.144

0.277

0.401

0.516

0.624

0.723

0.815

0.901

0.981

1.055

1.123

1.187

2000

0.288

0.555

0.803

1.033

1.247

1.446

1.630

1.802

1.961

2.109

2.247

2.344

3000

0.431

0.832

1.204

1.549

1.871

2.169

2.446

2.703

2.942

3.164

3.370

3.561

4000

0.575

1.109

1.605

2.065

2.494

2.892

3.261

3.604

3.922

4.218

4.493

4.748

5000

0.719

1.386

2.007

2.581

3.118

3.614

4.076

4.505

4.903

5.273

5.616

5.936

6000

0.863

1.664

2.408

3.098

3.741

4.337

4.891

5.406

5.883

6.327

6.740

7.123

SPEED OF BELT, IN

FEET,

PER MINUTE.

Horse-power transmitted for arc of contact of

130°

140°

150°

160°

170°

180°

190°

200°

210°

220°

230°

240°

100

0.125

0.130

0.135

0.140

0.144

0.149

0.152

0.156

0.159

0.162

0.165

0.168

200

0.249

0.260

0.270

0.280

0.289

0.297

0.305

0.312

0.318

0.324

0.330

0.335

300

0.374

0.390

0.405

0.420

0.433

0.446

0.457

0.468

0.477

0.487

0.495

0.503

400

0.499

0.521

0.540

0.560

0.578

0.594

0.609

0.624

0.637

0.649

0.660

0.671

500

0.623

0.651

0.675

0.700

0.722

0.743

0.762

0.779

0.796

0.811

0.825

0.838

600

0.748

0.781

0.810

0.840

0.867

0.891

0.914

0.935

0.955

0.973

0.990

1.006

700

0.873

0.911

0.935

0.980

1.011

1.040

1.066

1.091

1.114

1.135

1.155

1.174

800

0.997

1.041

1.080

1.120

1.155

1.188

1.219

1.247

1.273

1.298

1.320

1.341

900

1.122

1.171

1.215

1.260

1.300

1.337

1.371

1.403

1.432

1.460

1.485

1.509

1000

1.246

1.301

1.350

1.400

1.444

1.485

1.523

1.559

1.592

1.622

1.650

1.677

2000

2.493

2.603

2.699

2.800

2.888

2.970

3.047

3.117

3.183

3.244

3.301

3.353

3000

3.739

3.904

4.048

4.200

4.333

4.456

4.570

4.676

4.774

4.866

4.951

5.030

4000

4.986

5.206

5.398

5.600

5.777

5.941

6.093

6.235

6.366

6.488

6.601

6.707

5000

6.232

6.507

6.747

7.000

7.221

7.426

7.616

7.793

7.957

8.110

8.252

8.383

6000

7.478

7.809

8.097

8.401

8.665

8.911

9.140

9.352

9.549

9.731

9.902

10.060

Speed of Belt in

Feet Per Minute.

Horse-power transmitted for arc of contact of

2700

2800

2900

3000

310°

320°

380°

3400

350°

3600

100

0.170

0 172

0.175

0.176

0.178

O.180

0.182

0.183

0.184

0.186

0.187

0.188

200

0 340

0.845

0.849

0.353

0.356

0.860

0.363

0.866

0.369

0.371

0.374

0.376

800

0.510

0.517

0.524

0.529

0.535

0.540

0.545

0.549

0.553

0.557

0.560

0.564

400

0.680

0.690

0.698

0 706

0.713

0.720

0.720

0.732

0.737

0.742

0.747

0.751

500

0.851

0.862

0.872

0.882

0.891

0.900

0.908

0.915

0.922

0.928

0.934

0.939

600

1.021

1.034

1.047

1.059

1.069

1.080

1.089

1.098

1.106

1.114

1.121

1.127

700

1.191

1.207

1.221

l.235

1.248

1.200

1.271

1.281

1.290

1.299

1.307

1.315

800

1.361

1.379

1.396

1.412

1.426

1.440

1.452

1.464

1.475

1.485

1.494

1.503

900

1.581

1.551

1.570

1.588

1.004

1.620

1.634

1.647

1.659

1.670

1.681

1.691

1000

1.701

1.724

1.745

1.765

1.782

1.800

1.815

1.880

1.843

1.856

1.868

1.879

2000

3.402

3.488

3.490

3.529

3.564

8.599

3.631

3.660

3.687

3.712

3.735

3.757

3000

5.103

5.171

5.235

5.293

5.346

5.399

5.446

5.490

5.530

5.568

5.003

5.636

4000

6.804

7.240

6.980

7.058

7.129

7.198

7.261

7.819

7.374

7.424

7.471

7.514

5000

8.505

8.619

3.724

8.822

8.911

8.998

0.070

9.149

9.217

9.280

9.338

9.393

6000

10.206

10.343

10.469

10.587

10.698

10.798

10.892

lO.979

11.060

11.136

11.206

11.271

Example.-What horse-power can be transmitted by a leather belt 10 Inches wide, making an angle of contact of 80 with the smaller of the two pulleys over which it passes, and having a speed of 2400 feet per minute? Ans.-Horse-power for a belt 1 inch wide and 2000 feet speed is 1.802; horse-power for a belt 1 inch wide and 400 feet speed is 0.300; therefore, by addition, horsepower of 1 inch belt for 2400 feet speed is 2.162; and for 10 horsepower, 10 times 2.162, or 21.62.

V. To find the width of belt necessary to transmit a given amount of power for a given arc of contact and given speed in feet per minute.

Find the power transmitted by a belt 1 inch wide, and divide the given power by this amount.

Example.-An open belt passes over two pulleys having diameters of 4 and 6 feet respectively, and the former makes 300 revolutions a minute. The distance between the centres of the pulleys is 15 feet. What should be the width of a belt to transmit 50 horse-power under these circumstances? Speed of belt in feet per minute, 3770; arc of contact of belt with smaller pulley, 172'; horse-power transmitted by a belt 1 inch wide, under conditions in table nearest to those determined above {i.e., for arc of contact of 170 and speed of 3800), 5.488. Required width of belt, 50 divided by 5.488, or a little over 9 inches.

VI. In the use of a leather belt, it is best to run it with the grain side next to the pulleys, or in exactly the opposite way from that in which the hide was worn by the animal that was the original proprietor of the leather.

VII. Lace-leather is better than hooks for fastening the ends of a belt together; and a still better method, after a belt has become sufficiently stretched by use, is to rivet the ends together with long laps. In lacing a belt of any considerable size, make two rows of holes in each belt end, and put in double lacing.

VIII. A belt that is made of good material, and is of ample size, will last for many years, if kept clean, and prevented from becoming dry and hard by the use of neat's-foot oil. It is poor economy to buy a belt whose chief recommendation is its small first cost. It is also a bad plan to use a belt that is just sufficient to transmit the power when very tightly strained. B.

Corner Turned Belt

Corner-Turned Belt

Belts, Corner-turned, Device for.-The two shafts placed at right angles, as shown in the engraving, carry the belt from A or B, passing around two flanged pulleys or guides, C, turning loosely 011 a fixed upright shaft, and sustained in position by a collar under the hub of each. It is possible to run pulleys by this device which not only have varying diameters, but the shafts of which are on different levels; but the results are not so good, owing to unequal strain on the belt. It is better to confine this method to shafts on the same level, and to pulleys of equal diameter, and the useful limit of angle of shafts is that of 45°, or less. A greater or more obtuse angle is better run by means of guides on two uprights.