Lab Manual | To study various types of steering mechanisms

To study various types of steering mechanisms.

APPARATUS USED: -. Steering Mechanism Apparatus.

THEORY: –

STEERING GEAR :- When an automobile takes turn on a road all the wheels should make concentric circle to ensure that they roll on the road smoothly and there is line contact between the tyres and the surface of the path, preventing the excess wear of the tyres.this is achieved by mounting the two front wheels on two short axles, known as stub axles. The stub axles are pin jointed with the main front axle which is rigidly attached to the rear axle. Thus the steering is affected by the use of front wheels only.

 

1. Definition of. Steering mechanisms

2. Classification of steering mechanisms

3. Diagrams of different types of steering mechanisms

4. Working & Construction of different types of steering . .

. mechanisms.

5. Advantages & Disadvantages of steering mechanisms

6. Applications of steering mechanisms.

7. Examples of steering mechanisms

STEERING GEAR :- When an automobile takes turn on a road all the wheels should make concentric circle to ensure that they roll on the road smoothly and there is line contact between the tyres and the surface of the path, preventing the excess wear of the tyres.this is achieved by mounting the two front wheels on two short axles, known as stub axles. The stub axles are pin jointed with the main front axle which is rigidly attached to the rear axle. Thus the steering is affected by the use of front wheels only.

TYPES OF STERING GEARS :-

There are two main types of steering gears :

1. The Davis steering Gear

2. The Ackermann steering gear

DAVIS STEERING GEAR :- A Davis steering gear has sliding pairs which means more friction and easy wearing. The gear fulfils the fundamental equation of gearing in all the positions. However, due to easy wearing it becomes inaccurate after some time. A davis steering shown in fig. consists of two arms PK and QL fixed to the stub axles PC and QD to form two similar bell crank levers CPK and DQL pivoted at P and Q respectively. A cross link AB, constrained to slide parallel to PQ, is pin jointed at its ends to two sliders. The sliders S 1 and S2 are free to slide on the links PK and QL respectively. During the straight

motion of the vehicle, the gear is in the mid-position with equal inclination of the arms PK and QL with PQ.

As the vehicle turns right, the cross-arm AB also moves right through a distance x from the mod-position as shown in fig. the bell crank levers assume the positions C´ P K´ and D´QL´.

tana = w/2l (l = wheel base, w = distance between the pivots of front axle)

usual value of w/l is between 0.4 to 0.5 and that of a from 11 to 14 degrees.

ACKERMANN STEERING GEAR :- An Ackermann steering gear has only turning pairs and thus is preferred. Its drawback is that it fulfils the fundamental equation of correct gearing at the middle and the two extreme position and not in all positions. This steering gear consists of a four link mechanism PABQ having four-turning pairs.

Three positions of the correct gearing are-

1. when the vehicle moves straight.

2. when the vehicle moves at a correct angle to the right, and

3. when the vehicle moves at a correct angle to the left.

OBSERVATION & CONCLUSION:- 1. Type of Motion to be named.

VIVA-QUESTIONS :-

i. what do you mean by steering?

ii. What is the difference between the Davis & Ackermann steering gear mechanism?

iii. What is correct fundamental equation of steering gear mechanism?

iv. What do you mean by stub ?