Design and calculation of a truck with a 4x2 wheel formula, lifting capacity of 6t, and maximum speed of 90 km/h

Contents

Introduction

1. Calculation of car parameters

1.1 Design vehicle operating conditions and prototype selection

1.2. Vehicle weight determination, tyre size selection

2. Calculation of engine parameters

2.1 Calculation of engine power at maximum

vehicle speeds

2.2 Construction of external speed characteristic

3. Determination of transmission parameters

3.1Compute the gear ratio of the main gear

3.2 Calculation of gearbox first gear ratio

3.3 Calculation of intermediate gear ratios of CP

Calculation of total transmission gear ratio

4. 4 Traction balance of the car

4.1 Speed characteristic of traction force on driving wheels

4.2 Vehicle Resistance Forces

4.3 Vehicle traction balance diagram

5. Power balance

5.1Compute components of power balance

6. Time and way to accelerate the car

6.1Dynamic factor of the car

6.2 Vehicle Acceleration

6.3 Acceleration time and path

6.4 Design characteristic of fuel economy of the vehicle

7. Strength calculation of rear wheel brake device

7.1 Requirements, classification, applicability

7.2 General performance of brake actuators

7.3 Drum brake

7.4 Evaluation of block drum mechanisms of various types

7.5 Design and calculation of drum brake mechanism

7.6 Calculation of brake hydraulic drive

Conclusion

List of literature used

Appendix A Specification to brake assembly drawing

List of attached graphic material

1 Drawing of general view of designed car

2 Brake assembly drawing

3 Detail drawing of strip spacer

4 Detail drawing of brake cylinder housing

5 Kinematic diagrams of various braking mechanisms

Introduction

Road transport is now the most common land mode of transport. This is due to its ability to solve a wide range of problems, ease of use and the relative cheapness of both the creation of automotive equipment and its operation.

The widespread use of road transport on the one hand has solved many problems of economic and social importance. On the other hand, like any other achievement of constantly developing science and technology, the car brought with it many problems, often questioning the feasibility of its existence in such large quantities in these conditions.

The biggest problems of road transport are human safety and environmental conservation. Therefore, at present, the desire of automotive designers to make their brainchild more economical, small in urban conditions, environmentally less harmful, relatively silent and safe for both the driver and passengers, and for people outside the car is noticeable.

The development of road transport has led to the fact that now the car is a whole complex, the embodiment of the most advanced achievements of science, technology, production, design. And the problems created by the car can be solved only in a complex, taking into account the existing trends in the development of scientific and technological progress and, if possible, adjusting them in the right direction. This requires an appropriate scientific and production base. At the same time, it is important to train qualified personnel interested in the worthy development of the domestic automotive industry.

1 Calculation of car parameters

1.1 Design vehicle operating conditions and prototype selection

Designed car class 45 with maximum speed in the highest gear = 90 km/h, designed to carry cargo weighing up to 6 tons, type of engine gasoline.

Position of the engine in front of the cockpit, with four speed gearbox.

When performing the calculation, some data are taken based on the average values ​ ​ characteristic of existing car designs.

Minimum engine speed by external speed characteristic is accepted (for gasoline engine) 800 〖 min〗^ (-1). [1]

The maximum resistance overcome by the car on the first transfer Ψ _ max=0.33.

The rolling resistance coefficient of the wheels is selected for dry asphalt, then eats f = 0.02.

According to the task, there is no road lifting, therefore, there is also no resistance to lifting: i = 0.

Tyre deformation factor (for rolling radius calculation)? = 0.95.

δ - coefficient of accounting of rotating masses, we determine by formula 1:

δ=1+0,07*〖i_k〗^2 (1)

where i _ k is the gear ratio of the corresponding transmission.

The maximum speed of the external speed characteristic is equal to the nominal speed.

Traction coefficient of driving wheels with road A = 0.7.