Rack Jack Drive - Machine Parts

Contents

1. Terms of Reference p

2. Introduction of pages

3. Kinematic, energy and power calculation pp

4. Calculation of cylindrical gears

4.1. Calculation of helical transmission pp

4.2. Calculation of spur gear pp

5. Sketched Design

5.1. Diameters of shafts pp

5.2. Dimensions of shaft sections pp

5.3. Distance between gear parts pp

6. Selection and calculation of bearings

6.1 Input shaft p

6.2. Intermediate shaft pp

6.3. Output shaft pp

7. Refined shaft calculation

7.1. To Create Bending Moment Symbols

7.1.1. Input shaft p

7.1.2. Intermediate shaft pp

7.1.3. Output shaft pp

7.2. Calculation of shafts for strength

7.2.1. Input shaft p

7.2.2. Intermediate shaft pp

7.2.3. Output shaft pp

8. Calculation of key joints pp

9. Design of gear wheels pp

10. Justification for selection of bearing covers structure

11. Sizing of gearbox housing elements

12. Grease of reduction gear box

12.1. Lubricating devices pp

13. Selection and calculation of couplings of pages

14. List of literature pages

Introduction

The purpose of the course project is to design a drive to the rack jack, including: electric motor; a two-stage cylindrical reduction gear with a spaced high-speed stage (a reduction gear is a mechanism consisting of gear cylindrical gears that serves to transfer movement from the engine to the working body with a decrease in speed and an increase in torque and chain transmission).

The objective is achieved by:

- selection of electric motor and kinematic calculation of drive;

- gearing calculation;

- preliminary calculation of shafts;

- refined calculation of shafts;

- serviceability check of bearings;

- selection of reduction gear box lubrication;

- check of key connection strength;

- selection of couplings.

Drive units are mounted on welded frame.

Industrial oil I-G-A-32 is used to lubricate friction surfaces of reduction gear parts, gear wheels are lubricated by immersion in bath with liquid lubricant in lower part of reduction gear case by crankcase method. Other units and parts, including rolling bearings, are lubricated due to oil spraying by submerged wheels and circulation of formed oil mist inside the housing.

Sealing devices are used to prevent the lubricant from flowing out of the gearbox body or taking it out in the form of oil mist and splashes, as well as to protect them from dust and moisture ingress from the outside.

Reduction gear box lubrication

To reduce friction power losses and wear intensity of friction surfaces, as well as to protect them from jamming, corrosion bursts and better heat removal, the friction surfaces of the parts must have reliable lubrication.

For the design of the gear box, the crankcase lubrication system, the most common in mechanical engineering, is used. Oil is poured into the gear box housing so that wheel rims are immersed in it. When they rotate, the oil is carried away by the teeth, sprayed onto the inner walls of the body, from where it flows into its lower part. Inside the housing, a suspension of oil particles is formed in the air, which covers the surface of the parts located inside the housing. Crankcase lubrication system is used at circumferential speed of gears up to 12.5 m/s. In our case, the circumferential speeds of the high-speed and slow-speed stages are within these limits, so the use of such a lubrication system is quite justified.

The choice of lubricant is determined depending on the contact stress and the circumferential speed of the wheels. For gears, contact stresses of which do not exceed 600 MPa, and circumferential speeds less than 2 m/s, the recommended kinematic viscosity is 34 mm2/s. The reducer is intended for work at a temperature ≤ 40 wasps. All the listed conditions correspond to industrial oil I-G-A-32 (I - industrial oil, D - group by purpose: for hydraulic systems, A - group by operational properties: oil without additives, 32 - kinematic viscosity class).

In a two-stage gear at a circumferential speed of < 1 m/s (as in our case), it is necessary to immerse the wheels of high-speed and slow-speed stages in oil. The maximum level is taken equal to a third of the radius of the low-speed stage wheel.

Bearings are lubricated with the same oil as gear parts flowing from the walls of the housing and falling in the form of oil mist.

12.1. Lubricating devices.

During the operation of the transmissions, the oil is gradually contaminated with wear products. As time goes on, it gets older. Its properties are deteriorating. Therefore, the oil poured into the gearbox housing is periodically changed. For this purpose, a drain hole is provided in the housing, which is closed by a plug with a cylindrical thread.

To monitor the oil level in the housing, rod oil indicators (probes) are installed. The design of the inclined probe causes some technological difficulties in forming the body and drilling the inclined hole, so a vertical design is preferable.

During long-term operation due to heating of oil and air, the pressure inside the housing increases, which leads to oil leakage through seals and joints. To avoid this, the internal cavity of the housing is communicated with the external environment by installing perfumes at its upper points.