| Page 57 | Mechanical Engg Simple Notes ,Solved problems and Videos

What do you mean by crowning of pulleys in flat belt drive ? State its use.

1. As no slip takes place, hence, perfect velocity ratio is obtained (Positive drive). 2. Chain drive gives high transmission efficiency (up to 98 %). 3. Chain drive may be used when the distance between the shafts is less. 4. Chain is made up of metal which would occupy less space as compared with belt or rope drive. 5. Ability to transmit power to several shafts by one chain. 6. Load on the shaft is less and long life.

(b) Define : (i) Radial follower (ii) Off-set follower

1. According to the surface in contact:  Knife-edge follower  Roller follower  Flat faced or mushroom follower  Spherical follower 2. According to the motion of the follower:  Reciprocating or translating follower  Oscillating or rotating follower 3. According to the path of motion of follower:

Radial follower Off-set followe

(a) Define : (i) Spherical pair (ii) Higher pair

a) Single plate clutch b) Multi plate clutch c) Cone clutch d) Centrifugal clutch

ii) Classification of follower:

A single plate clutch, effective on both sides, is required to transmit 25 kW at 3000 rpm. Determine the outer and inner radii of frictional surface, if the co-efficient of friction is 0.255 the ratio of radii is 1.25 and the maximum pressure is not to ex

A simple band brake is operated by lever 40 cm long. The brake drum diameter is 40 cm and brake band embrance 5/8 of its circumference. One end of band is attached to a fulcrum of lever while other end attached to pin 8 cm from fulcrum. The co-efficient o

Simple band brake:

Given: Length of lever l = 40 cm = 0.4m, diameter d = 40 cm = 0.4, µ = 0.25, b =0 .08 m ϴ = Angle of wrap = 5/8 x 360 = 225 x π /180 = 3.93 rad Braking torque = (T1 –T2) x r T1/T2 = e µϴ = e 0.25 x 3.93 = 2.67 Taking moments about fulcrum P x l = b x T1 500 x 0.40 = 0.08 x T1 T1 = 2500 N T2 = 2500 / 2.67 = 936.3 N Braking Torque = (2500 – 936.3) x 0.2 = 312.74 N-m

Draw turning moment diagram for single cylinder four stroke I.C. Engine.

ii) Turning Moment Diagram:

State types of gear train and explain any one.

i) Types of gear trains 1) Simple gear train 2) Compound gear train 2) Epicyclic gear train 4) Inverted gear train Simple gear train. When there is only one gear on each shaft, it is known as simple gear train. The gears are represented by their pitch circles. When the distance between the two shafts is small, the two gears are made to mesh with each other to transmit motion from one shaft to the other Epicyclic gear train: A simple epicyclic gear train is shown in Fig. where a gear A and the arm C have a common axis at O1about which they can rotate.

Two pulley, one 450 mm diameter and the other 200 mm diameter are on parallel shafts 1.95 m apart and are connected by a crossed belt. Find the length of the belt required and the angle of contact between the belt and each pulley. What power can be transm

Draw the profile of a cam to raise a valve with S.H.M. through 40 mm in of revolution, keep it fully raised through 1/10 th 1 th 4 revolution and to lower it with uniform acceleration and retardation in 1/6 th revolution. The valve remains closed during t

Fig shows a displacement diagram and a cam profile for the roller follower.

The crank of a slider crank mechanism rotates clockwise at a constant speed of 300 rpm. The crank is 150 mm and the connecting rod is 600 mm long. Determine : (i) linear velocity and acceleration of the mid-point of the connecting rod, and (ii) angular ve

Note: Since D is the midpoint of AB, therefore d' is also midpoint of vector b' a'. Join o' d'. The vector o' d' represents the acceleration of midpoint D of the connecting rod i.e. aD.

By measurement, we find that aD = vector o' d' = 117 m/s2

Given: Lift = 40 mm Rise = ¼ x 360 = 900 Fall =1/6 x 360 = 600 Dwell = 1/10 x 360 =360

Mechanical Engg Simple Notes ,Solved problems and Videos

You are here