Answer to Question #159076 in Mechanical Engineering for mohamed

Question

DESIGN OF A SPEED REDUCER WITH SPUR GEARS

 

Consider that you are the designer of a speed reducer that is part of of the power transmission for a tractor. The Tractor’s engine operates at a fairly high speed, while the drive for the wheels must rotate more slowly and transmit a higher torque that is available at the output of the engine.

 

The design process will start first by listing the functions of the speed reducer or the functional requirements of the reducer. Some probable functions can be stated as follows:

Functions:

1.         To receive power from the engine of the tractor through a rotating shaft.

2.         To transmit the power through machine elements that reduce the speed to a desired value.

3.         To deliver the power at a lower speed to an output shaft that ultimately drives the wheels of the tractor.

 

Secondly the design requirements shall be stated. As a member of the design team for the tractor, you would be able to identify such requirements from your own experience and ingenuity and or by consultation with fellow designers, marketing staff, manufacturing engineers, service personnel, suppliers, and customers.

 

The product realization process calls for personnel from all of these functions to be involved from the earliest stages of design.

 

 

 

 

Design Requirements:

1.    The reducer must transmit H_in [kW] power. (Note that power assignment is listed for each student separately in kW!)

2.    The input is from a six-cylinder diesel engine with a rotational speed, n_in = 2000 rpm.

3.    The output shaft of the reducer delivers the power at rotational speed n_out = of 290 ± 1 rpm. (Output speed is the same for all students!)

4.    A mechanical efficiency of greater than 95 % is desirable.

5.    The minimum output torque capacity of the reducer should be _______ N-m. (This output torque will depend on your input power and the specified output speed.)

6.    The reducer output shaft is connected to the drive shaft for the wheels of the farm tractor. Therefore, a moderate shock (at output) will be encountered.

7.    The input and output shafts must be inline.

8.    The reducer (gear) housing is to be fastened to a rigid steel frame of the tractor.

9.     Small size is desirable. (e.g., your gearbox size will depend on the transmitted power assigned to you) must be given as Width x Length times heigth)- - given such as, 510 x 510 mm with a maximum height of 610 mm. (These will differ for your case!)

10. The tractor is expected to operate 8 hours per day, 5 days per week, with a design life of 15 years.

11. The reducer must be protected from the wheather and must be capable of operating anywhere at temperatures ranging from -5 b ⁰ C to 55 ⁰ C.

12. Flexible couplings will be used on the input and output shafts to prohibit axial and bending loads from being transmitted to the reducer.

13. The production quantity is 1 000 units per year!

14. Moderate cost is critical to successful marketing.

15. All government and industry safety standards must be met (this shall add a bonus for every positive answer.).

Answer 1

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