Machine Parts Course Design: Coaxial Gearbox (5 sheets + RPZ)

Contents

INTRODUCTION

1. KINEMATIC CALCULATION OF DRIVE

2. SELECTION AND CALCULATION OF COUPLINGS

3. GEARBOX HIGH SPEED TRANSMISSION CALCULATION

4. LOW-SPEED GEAR GEARBOX CALCULATION

5.STRUCTURAL DIMENSIONS OF GEARBOX HOUSING AND COVER

6. CALCULATION OF SHAFTS AND BEARINGS OF REDUCTION GEAR BOX

6.1 Input shaft calculation

6.2 Calculation of intermediate shaft

6.3 Calculation of output shaft

7. CALCULATION OF KEYWAY CONNECTIONS

7.1 Material selection and calculation method

7.2 Calculation of keys

8. SELECTION OF LUBRICANT FOR GEARS AND BEARINGS

8.1 Lubrication of gear

8.2 Lubrication of bearings

Literature

Introduction

A reduction gear is a mechanism consisting of geared or worm gears (wheels) made in the form of a separate unit and serving to transfer rotation from the shaft of the engine to the shaft of the working machine.

The purpose of the reduction gear is to reduce the angular speed and, accordingly, increase the rotational torque of the driven shaft compared to the driving one.

The reduction gear consists of a body (cast iron or welded steel), in which the transmission elements are placed - gears, shafts, bearings, etc. In some cases, other auxiliary devices are also placed in the housing.

Gearboxes are classified according to the following main features: gear type (toothed, worm or gear-worm);

number of stages (single-stage, two-stage, etc.);

to type of cogwheels (cylindrical, conic, konicheskotsilindrichesky, etc.);

relative location of gear box shafts in space (horizontal, vertical);

peculiarities of kinematic scheme (unfolded, coaxial, with bifurcated stage, etc.).

Two-stage cylindrical reduction gears.

The most common are two-stage horizontal gearboxes made according to an expanded scheme. These gearboxes are simple, but due to the asymmetric arrangement of the wheels on the shafts, the concentration of load along the length of the tooth increases. Therefore, rigid shafts should be used in these gearboxes.

Selection of lubricant for gears and bearings

9.1 Lubrication of Gear

Since we have a general-purpose gearbox and the circumferential speed does not exceed 12.5 m/s, we accept a crankcase lubrication system in which oil is poured into the gearbox housing so that the rims of the gears are immersed in it. When they rotate, the oil is carried away by the teeth, sprayed, falls on the inner walls of the body, from where it flows into the lower part of the body. Inside the housing, a suspension of oil particles is formed in the air, which covers the surface of the parts located inside the housing. For a conical-cylindrical reduction gear, the depth of immersion of the gears in the oil must be such that the conical wheel is submerged over the entire width of the gear rim.

As per [7] we determine that oil with kinematic viscosity of 28· 106 m2/s is required to lubricate the reduction gear box at circumferential speed of 2... 5 m/s and contact voltages up to 60 MPa. We accept I40A oil GOST 2079975 for lubrication of gear transmission. Control of oil level is performed by means of rod oil indicator. For oil replacement in the housing there is a drain hole closed by a plug with cylindrical thread. Internal cavity of housing communicates with external medium by means of perfume installed on cover. Oil is poured through the panel.

9.2 Lubrication of bearings

Lubrication of rolling bearings will be carried out from the reduction gear case as a result of oil spraying with a gear wheel. For this purpose, bearing cavities are made open inside the housing.