Lecture on Bennett’s Construction by Dr. Ambuj Saxena

1. Unit-III
Dynamic Force Analysis-III
Dr. Ambuj Saxena
Associate Professor
Department of Mechanical Engineering
G. L. Bajaj Institute of Technology and Management
Plot No. 2, Knowledge Park III,
Greater Noida, Distt. G.B.Nagar (U.P.) India -201306
Theory of Machines
(RME-602)

2. Bennett’s Construction
 OC is at right angle to the line of stroke, it
occupies the position OC1 and the crosshead P moves to
the position P1,
 Produce PC to intersect OC1 at M
Klien’s acceleration diagram
𝑣𝑐𝑜
𝑂𝐶
=
𝑣 𝑃𝑂
𝑂𝑀
=
𝑣 𝑃𝐶
𝐶𝑀
= 𝜔
Reference : R.S. Khurmi (Theory of Machines)
 The triangle OCM is known as Bennett’s velocity
diagram
Velocity and Acceleration of the Reciprocating Parts in Engines

3. Bennett’s Construction • From O, draw OL1 perpendicular to P1C1 (i.e. position of
connecting rod PC when crank is at right angle). Mark the
position of point L on the connecting rod PC such that CL =
C1L1.
• From L, draw LK perpendicular to PC and from point K draw
KQ perpendicular to the line of stroke PO. From point C,
draw CN perpendicular to the line of stroke PO. Join NQ. A
little consideration will show that NQ is perpendicular to
PC.
• The quadrilateral CQNO is known as Bennett’s acceleration
diagram. It is similar to Klien’s acceleration diagram.
Klien’s acceleration diagram Reference : R.S. Khurmi (Theory of Machines)