Chains

Question 1

What are the advantages of chains?

Answer 1

They are able to transmit power over large distances
Able to transmit high torques
Will provide exact speed ratios
Easy to maintain
Inexpensive

Question 2

What are the disadvantages of chains

?

Answer 2

They produce significant noise

Require adequate lubrication

Question 3

What is the most common chain type and what is it used for?

Answer 3

The roller chain. It is used for materials handling and conveying equipment.

Question 4

What are the characteristics of a roller chain??

Answer 4

Long pitch length
Large roller diameter
High tensile strength

Question 5

What are the components of a roller chain?

Answer 5

The outer plate with the bearing pins attached to it.

The inner plate with a bush, a roller then goes on top of this.

Question 6

How do we relate the pitch of the chain to the number of teeth?

Answer 6

If D is the pitch diameter of the sprocket, then

D = Np / pi

Question 7

What is the equation for speed ratios

Answer 7

w1 / w2 = N2 / N1 = D2 / D1

Question 8

What are the equations for torque ratios?

Answer 8

T1 / T2 = N1 / N2

Question 9

How do we find the angular velocity of a gear?

Answer 9

w1 = V2 / D1

V2 is the velocity of the largest gear.

Question 10

What is the equation for torque?

Answer 10

The normal equation: T = P / where P is Power

Can also use: T1 = PD1 / 2 Here P is the tension of the chain

Question 11

How are chain drives installed to allow them to transmit power?

Answer 11

They have one tight strand that transmits torque and power, and then the other strand is slack with negligible tension.

Question 12

How do we calculate the tension of the chain?

Answer 12

P = Power / (radius of gear x W)

Question 13

Why does the orientation of the chain have to be taken into consideration?

Answer 13

Because we have one slack strand, and so if this cannot be beneath the tight strand, then we need to introduce a tensioner mechanism to ensure efficient meshing of the sprockets at all times.

Question 14

Why do we have to take into account lubrication?

Answer 14

It helps to reduce the wear of the chain and so to increase the life. Typically the higher the transmitted power and the speed then the greater the lubrication method must be.

Question 15

What are the various lubrication types?

Answer 15

Manual
Drip feed
Oil bath

Question 16

How do we use chains in automobiles?

Answer 16

We can use them to as a substitute for synchronous cam belts. Chains will offer precise timing and higher breaking strengths which is required as the output of the motor increases.

Question 17

What is the typical selection procedure for a chain?

Answer 17

1. Define the power that needs to be transmitted
2. Determine the service factor
3. Calculate the design power, this is the transmitted power times the service factor
4. Knowing the design power and the speed of the small sprocket select chain pitch and number of teeth on the small sprocket.
5. Pick the large sprocket to get the desired speed ratio.
6. Calculate the length of the chain.
7. Calculate the exact distance between sprocket centres.