Mechanical Engineering Answers

In a pin jointed four bar mechanism ABCD, the lengths of various links are as follows:

A B = 25 mm ; BC = 87.5 mm ; CD = 50 mm and AD = 80 mm. The link AD is fixed and the angle BAD = 135°. If the velocity of B is 1.8 m/s in the clockwise direction, find 1. velocity and acceleration of the mid point of BC, and 2. angular velocity and angular acceleration of link CB and CD

The engine mechanism shown in Fig. 8.38 has crank OB = 50 mm and length of connecting rod A B = 225 mm. The centre of gravity of the rod is at G which is 75 mm from B. The engine speed is 200r.p.m. For the position shown, in which OB is turned 45° from O A, Find 1. the velocity of G and the angular velocity of A B, and 2. the acceleration of G and angular acceleration of A B.

An epicyclic train is shown in Fig. 13.42. Internal gear A is keyed to the driving shaft and has 30 teeth. Compound wheel C and D of 20 and 22 teeth respectively are free to rotate on the pin fixed to the arm P which is rigidly connected to the driven shaft. Internal gear B which has 32 teeth is fixed. If the driving shaft runs at 60 r.p.m. clockwise, determine the speed of the driven shaft. What is the direction of rotation of driven shaft with reference to driving shaft?

In an epicyclic gear train of the ‘sun and planet type’ as shown in Fig. 13.41, the pitch circle diameter of the internally toothed ring D is to be 216 mm and the module 4 mm. When the ring D is stationary, the spider A, which carries three planet wheels C of equal size, is to make one revolution in the same sense as the sun wheel B for every five revolutions of the driving spindle carrying the sunwheel B.

Determine suitable number of teeth for all the wheels and the exact diameter of pitch circle of the ring.

A compound epicyclic gear is shown diagrammatically in Fig. 13.40. The gears A, D and E are free to rotate on the axis P. The compound gear B and C rotate together on the axis Q at the end of arm F. All the gears have equal pitch. The number of external teeth on the gears A, B and C are 18, 45 and 21 respectively. The gears D and E are annular gears. The gear A rotates at 100 r.p.m. in the anticlockwise direction and the gear D rotates at 450 r.p.m. clockwise. Find the speed and direction of the arm and

the gear E.

A reverted epicyclic gear train for a hoist block is shown in Fig. 13.39. The arm E is keyed to the same shaft as the load drum and the wheel A is keyed to a second shaft which carries a chain wheel, the chain being operated by hand. The two shafts have common axis but can rotate independently.

The wheels B and C are compound and rotate together on a pin carried at the end of arm E. The wheel D has internal teeth and is fixed to the outer casing of the block so that it does not rotate.

The wheels A and B have 16 and 36 teeth respectively with a module of 3 mm. The wheels C and D have a module of 4mm. Find : 1. the number of teeth on wheels C and D when the speed of A is ten times the speed of arm E, both rotating in the same sense, and 2. the speed of wheel D when the wheel A is fixed and the arm E rotates at 450 r.p.m. anticlockwise.

An epicyclic reduction gear, as shown in Fig. 13.38, has a shaft A fixed to arm B. The arm B has a pin fixed to its outer end and two gears C and E which are rigidly fixed, revolve on this pin. Gear C meshes with annular wheel D and gear E with pinion F. G is the driver pulley and D is kept stationary.

The number of teeth are : D = 80 ; C = 10 ; E = 24 and F = 18. If the pulley G runs at 200 r.p.m. ; find the speed of shaft A.

Why need to add kinetic energy correction factor in the Bernoulli’s equation? How do you

determine the kinetic energy correction factor? Explain briefly. What is the difference between

pipe, tube and duct? Define water hammer.

An epicyclic gear train, as shown in Fig. 13.35, is composed of a fixed annular wheel A having 150 teeth. The wheel A is meshing with wheel B which drives wheel D through an idle wheel C, D being concentric with A. The wheels B and C are carried on an arm which revolves clockwise at 100 r.p.m.

about the axis of A and D. If the wheels B and D have 25 teeth and 40 teeth respectively, find the number of teeth on C and the speed and sense of rotation of C

In a reverted gear train, as shown in Fig. 13.32, two shafts A and B are in the same straight line and are geared together through an intermediate parallel shaft C. The gears connecting the shafts A and C have a module of 2 mm and those connecting the shafts C and B have a

module of 4.5 mm. The speed of shaft A is to be about but greater than 12 times the speed of shaft B, and the ratio at each reduction is same.

Find suitable number of teeth for gears. The number of teeth of each gear is to be a minimum but not less than 16. Also find the exact velocity ratio and the distance of shaft C from A and B.