Hello there! Have you ever wondered how to solve design problems based on flat belts? This tutorial is for you. It explains flat belt design in a step-by-step manner. Read every step carefully for good understanding. For reading convenience, this tutorial has been split into four pages
Solving Design problems based on Flat Belts:
There are two ways by which you can design a flat belt drive. They are:
- Designing flat belt drive using manufacturer’s data
- Designing flat belt drive using basic equations
Among the above two methods, the former is simple, easy and practically applicable. It involves the usage of data provided by flat belt manufacturers to solve design problems. It is covered in detail in this article.
In order to design a flat belt drive using manufacturer’s data, you need to find ten different parameters. They are:
- Pulley Diameters (D and d)
- Speeds of Driving and Driven Pulleys (N1 and N2)
- Design Power in KW
- Velocity of belt (V m/s)
- Selection of belt
- Number of plies
- Load rating at V m/s
- Belt width (b)
- Pulley width
- Length of belt (L)
You can click on any one of the links above to know how to find a particular parameter.
Steps involved in Designing Flat Belt Drives:
This step involves finding the diameters of the driving and driven pulleys of the belt drive. In some problems, diameters of the driving and driven pulleys may be given. If any one of them is not given, use the following equation to find it:
N1 → Speed of the driving pulley in rpm
N2 → Speed of the driven pulley in rpm
D → Diameter of the larger (driven) pulley in m
d → Diameter of the smaller (driving) pulley in m
Note: Here, we have assumed that the driven pulley is larger in diameter than the driving pulley.
After finding the pulley diameters, you must change it to the nearest standard value (greater than the one determined) and fix it as the permanent value.
A list of standard pulley diameters (in mm) is given below:
Note: If you are using PSG design data book, refer page no. 7.54 (May 2012 reprint) for finding the standard pulley diameter.
In many problems, the speeds of the driving and the driven pulleys will be given. If any one speed is not given, either the velocity ratio or the pulley diameters will be given. Use the same equation from the above step to find the unknown pulley speed.
The above formula can be used in any problem where percentage slip is zero (or not given). If percentage slip is given for each pulley, use the following equation to find the unknown pulley speed or diameter.
S1 → Percentage slip between the driving pulley and the belt
S2 → Percentage slip between belt and the driven pulley
If thickness of belt (t) is considered, use the following equation:
See the next page for the third step.