Disadvantages Of Chain Drive Mechanism

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2.1 Definition of chain drive mechanism

The basic rule of chain drive mechanism is to transmit power one shaft to another shaft at certain center distance with the help of sprockets and chain links.

Chain drives maintain a positive speed ratio between driver and driven sprockets. The driver and driven sprockets will rotate in the same direction on typical chain drives.

2.2 Definition of lever drive
Mechanism

The basic rule of the lever is a rigid bar resting on a pivot, used to move a heavy or firmly fixed load with one end when pressure is applied to the other.

There are three classes of lever mechanism which are as below:

In this case we are using second class of lever mechanism in our wheelchair.
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It is often used to convey power to the wheels of a vehicle, particularly bicycle and motorcycle. It is also used in a wide variety of machines besides vehicles.

Advantages:-

1.As no slip takes place during chain drive, hence perfect velocity ratio is obtained.
2.Since the chains are made of metal, therefore they occupy less space in width than a belt or rope drive.
3.It may be used for both long as well as short distances.
4.It gives a high transmission efficiency (upto 98 percent).
5.It gives less load on the shafts.
6.It has the ability to transmit motion to several shafts by one chain only.
7.It transmits more power than belts.
8.It permits high speed ratio of 8 to 10 in one step.
9.It can be operated under adverse temperature and atmospheric conditions.

Disadvantages:-

1.The production cost of chains is relatively high.
2.The chain drive needs accurate mounting and careful maintenance, particularly lubrication and slack adjustment.
3.The chain drive has velocity fluctuations especially when unduly
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So better power output

2.11 Requirements of lever

 To get high output force at low effort

 To get user friendly condition in wheelchair

2.12 Types of chain drive

The six styles of chain used for mechanical transmission are:
Roller chain
Detachable chain
Pintle chain
Silent chain
Leaf chain
Laminated metal chain

2.13 Types of lever

Class 1: Fulcrum in the middle: the effort is applied on one side of the fulcrum and the resistance (or load) on the other side, for example, a seesaw, a crowbar or a pair of scissors. Mechanical advantage may be greater than, less than, or equal to 1.
Class 2: Resistance (or load) in the middle: the effort is applied on one side of the resistance and the fulcrum is located on the other side, for example, a wheelbarrow, a nutcracker, a bottle opener or the brake pedal of a car. Load arm is smaller than the effort arm. Mechanical advantage is always greater than 1. It is also called force multiplier
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