Types of Engineering Curves

TYPES OF ENGINEERING CURVES

Engineering curves are basically classified into three types as below:

i) Rouletters, 

ii) Spiral curves, and 

iii) Helix

i) Rouletters: Rouletters are the curves generated by a fixed point on the circumference of a rolling curve which rolls without slipping along a fixed straight line or a curve. The fixed straight line is called as directing line and the fixed circle is known as directing circle (or) base circle. Important curves of Rouletters are :

1. Cycloid 

2. Epicycloid

3. Hypocycloid and 

4. Involute

Cycloid is a curve generated by a point on the circumference of a circle which rolls without slipping along a fixed straight line.

Epicycloid is a curve generated by a point on the circumference of a circle which rolls without slipping, around the outside of a fixed circle.

Hypocycloid is a curve generated by a point on the circumference of a circle which rolls without slipping along the inside surface of a fixed circle.

Involute is a curve traced out by a point on a straight line which rolls around a circle or a polygon, without slipping. 

It may also be defined as a curve traced out by a point on a taut inextensible string which is being wound around a circle or polygon.

Spiral curves: If a line rotates in a plane about one of its ends and at the same time, if a point moves continuously along the line from one end to the other, the curve traced out by the moving point is called a spiral.

Helix Helix is defined as a space curve generated by a point which moves on the surface of a cylinder or cone in a circumferential direction at a constant angular speed and with a simultaneous axial advancement at a uniform rate.